| Author | Message | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 37 Registered: 5-2003 |
David, with the addition of the turbos, I can easily agree with your ideas. Hair dryers added to an engine not origionally designed for them is a major problem waiting to happen! When I was doing these cars under warranty I ran across things that I never thought could happen. Most of it was generated by the fact that someone was behind the wheel of a car that was covered bumper to bumper with the warranty! I too fully expected to find a carbon flake causing the problem (as with the last 3 or 4 355's I have had the heads off of), this is why I did the amount of tapping on the follower with the leak down attached, hopeing to dislodge it, and carry on with a std. belt replacement and cam timing. Your thoughts about a bent valve are also very well with in reason, as an accidental down shift could do this easily, though I have not personally run across this on a 355 yet. The last thing I need or want is to drop this bomb shell on a friend and customer. | ||
| David Moore (Speedmoore)
Junior Member Username: Speedmoore Post Number: 52 Registered: 4-2003 |
Dave said: "I have only serviced Ferraris that led a very sheltered life." Yea, Sorry I forgot to qualify that comment by mentioning some of those issues were "enhanced" by the addition of a turbocharger with bad gas and high boost......or a NA racing engine where they are far from living a sheltered existance;-)_ D | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 34 Registered: 5-2003 |
Compression test showed the problem, leak down verifyed it and pointed it out to be an exhaust valve problem. Leak down was performed again with the cam cover off while tapping on the cam follower with a soft brass punce to try to dislodge possible carbon build up. After 15-20 trys doing this, the leak down remained identical to what my first readings were. I fully expected to find a burnt exh. valve, as I suspected it had the new iron guides in it, given it is a 97. Quite a shock to find the guides worn as they were(read above post about 97 valve guides) I did numerous valve jobs at the dealership on 95's, never found one this bad. I have never found a cracked liner in any Ferrari short of one that had a catastrophic failure. For that matter I dont recall a blown head gasket that caused a compression problem either. That takes it back 25+ yrs ago for me, but maybe I have only serviced Ferraris that led a very sheltered life. | ||
| David Moore (Speedmoore)
New member Username: Speedmoore Post Number: 50 Registered: 4-2003 |
Hmmmm: Frankly if you have 30% leakage you probably do have a problem. Compression Test of the numbers you found indicated that first. Leak dn points to where the problem is to help diagnose how to tackle the repair. I'd have to say JRV's comments are dead on the money. We do both compression and leak-dn tests. Compression is a quick easy test to find something big. The Leak down narrows down and helps diagnose the problem. I can usually tell via a leakdown test if it is rings/piston, intake valve, exhaust valve, head gasket, or maybe even a cracked cylinder, etc. It's not uncommon to see leak numbers right around 8-10% on a 355 cold in good shape. Hot/warm will bring them down to under 5%. I personally think it's a good thing to do leak dn both cold and hot as a cold leak-dn can find a broken ring that you may not find hot (seen it first hand). There is lots of room for error. However, if I see a bad reading, I usually roll the engine over and check it several times. I also will roll the engine with the air pressure attached to watch what the needle does as the valves open and close. From my experience, with a car that low on miles/hours, anything over 20% leak is 9 times out of 10 due to a slightly bent valve from an over-rev. But, for 30 and beyond % leak, I've seen cracked combustion chamber at the spark plug hole, valve seat, chipped/cracked piston, detonation damage to piston, burned valves, bent valves, loose valve seat, cracked head around seat, cracked liner, broken piston rings, blown head gaskets, loose head bolts/studs, "Carbon on the valve", carbon on the seat, etc, etc. My 2 cents. I'm curious to what their leakdown pointed too and then what you eventually find. It ain't rocket science. To make compression, the valves, rings, gasket, combustion chamber dome, piston, and the liner areas have to seal up. Obviously they never seal 100%. Best you will ever see is 2% when everything is perfect. | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 60 Registered: 10-2002 |
P. Thomas.. You're absolutely right about "variances" being the indicia. Those adjacent 130/135 readings are what's troublesome, overall. As I noted in an earlier post, 99% of the time, that indicates a head gasket/cracked cylinder head problem. Andy | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 9 Registered: 5-2003 |
I am taking it in to either Orange County Ferrari or Auto Gallery. Both service managers (both named Allen) are terrific, at least on the phone. The Orange County guy said they do compression tests cold! He also said don't sweat it though I am a bit our of spec for variances. Have not spoken to Auto Gallery on this specific topic yet. What is most interesting is I have a friend that works for FMF, the company that makes pipes for motorcycles. He kind of giggles and states that a good mechanic would be able to do a deeper diagnosis of what the specific problems is during a leakdown... | ||
| P. Thomas (Ferrari_fanatic)
Member Username: Ferrari_fanatic Post Number: 298 Registered: 4-2003 |
Good info Tim. Kevin whether your car is symptomatic or asymptomatic right now, I would say that based on the compression figures, you really could have something going on. The side by side low numbers on adjacent cylinders are quite compelling. | ||
| Tim Barnett (Tim_barnett)
New member Username: Tim_barnett Post Number: 28 Registered: 4-2003 |
I don't want to scare you Kevin, but this may be food for thought. http://www.ferrarichat.com/discus/messages/112/256560.html?1054082717 | ||
| P. Thomas (Ferrari_fanatic)
Member Username: Ferrari_fanatic Post Number: 278 Registered: 4-2003 |
This thread has turned in to somewhat of a debate on methadology. The fact remains the same. There is a SIGNIFICANT variance in the high and low #s of his compression test. Provided the battery is fully charged, and the cranking speed is constant, small variables such wide open throttle, battery drain towards the end of the test, etc., will affect the raw numbers. Regardless of HOW the test was done ,if the mechanic is COSISTENTin his procedure, you are looking for a VARIANCE, not just raw numbers. Further exasperating the raw numbers are the type of compression gauge. Some gauges have the shrader release valve AT THE BOTTOM of the hose. While others have the release VALVE AT THE TOP of the hose. The gauge with the release valve on the TOP uses the ENTIRE hose as part of the combustion chamber, therefore causing a lower reading. But again the fact remains the same. He has a SIGNIFICANT VARIANCE in the two adjoing cylinders. The CAT cleans up a TON of that crap. Just passing the smog test is not 100% reliable. If you took an UPSTREAM reading then yes it would be MUCH more indicative of the efficancy of the cylinders. | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 53 Registered: 10-2002 |
Dave... ever get hold of Tim? Be interesting to hear his take on this one. It's easy to get confused about the ultimate pressure a cylinder can pump up - compression test - and how well it can hold the pressure - leak-down test - and the relationships between the two. Kevin... I'm getting old - I was a decade off, it had to be '58 or '59 I first saw an Isetta. There's a VW wrench in Pompano Beach here that had 5 or 6 in various states of disrepair and/or restoration. They're just so innovatively neat!! PS... might have to fold your legs for a burial, huh?  Andy | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 8 Registered: 5-2003 |
Hey Andrew.... The Isetta was used on a goat ranch in Santa Barbara. It had a frame off restoration...even the steering wheel was re-done. It is really fun. It is pretty peppy. 4 speed transmission. Single cylinder BMW engine. Gets more attention than anything else I have ever had. Without peers. Especially in that color, which is Kawasaki green. A true Isetta afficianado may not approve! The day after I got it, I had huge buyers remorse. For some reason. Now I love it. They can bury me in it. | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 29 Registered: 5-2003 |
Terry, as you said, every thing in moderation. Yes, it wont hurt the engine, but gobs of carbon can raise quite an issue if they get lodged in a cat. when it is less than full operating temp. Side note, I was told the WW2 bombers had the engines pulled and torn down when ever the throttles were "put through the wire". I remember my dad telling me about one time his plane (B24) was over loaded on a short strip in the S Pacific, and it lost a tire on take off. It was put through the safty wire on the throttles. He said it took off like a scalded dog, the whole plane shook, they circled the island and landed, and were grounded while the mechanics replaced the engines. Albeit, this was set up to happen at full throttle. Interesting idea though. I remember it was a fairly common mod. for RV's back in the 70's. The power of steam!! | ||
| Terry Springer (Tspringer)
Member Username: Tspringer Post Number: 525 Registered: 4-2002 |
Hows this for a little trick. I have not used this in years, but have done it on several Porsches and Jaguars. Before you do the compression or leakdown test, with the engine hot, spray cool water directly into the intake of each carb / injection stack while revving the engine. Use a spray bottle that gives good atomization. Dont spray so much that it kills the cylinder for more than a second or so. This is a great way to clean the carbon off the valves and piston crown. It will usually puff out a good bit of black sooty smoke and you may even see carbon nasty stuff come out the exhaust. After doing this, the piston crowns will be nice and clean. You will be more likely to get a clean compression / leakdown test. This will not harm the engine. Remember... WWII fighters used to run water injection systems to prevent detonation under high boost. It cools the intake charge. They would add methanol to the water to keep the burn up. | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 48 Registered: 10-2002 |
Kevin... I just saw your website... a Bimmer Isetta??? Geeze.. I'd KILL to get my hands on a good one!! I first saw one at an auto show in Omaha.. hadda be '68 or '69... and have LOVED them since, though I never got one. | ||
| Steven R. Rochlin (Enjoythemusic)
Member Username: Enjoythemusic Post Number: 453 Registered: 4-2002 |
Kevin, That is GREAT news :-) Enjoy the Drive, Steven R. Rochlin | ||
| Tim Barnett (Tim_barnett)
New member Username: Tim_barnett Post Number: 23 Registered: 4-2003 |
Dave, You have email. Tim | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 7 Registered: 5-2003 |
One more note... ferrari of beverly Hills stated that if I did have such a failure in a leakdown and compression then I would fail my smog test. I just did one today and it passed. | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 28 Registered: 5-2003 |
Calling Tim Barnett, time to pipe in! Guys, never say never! More to follow......... | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 27 Registered: 5-2003 |
Calling Tim Barnett, time to pipe in! Guys, never say never! More to follow......... | ||
| James Selevan (Jselevan)
Member Username: Jselevan Post Number: 563 Registered: 6-2002 |
Mark - well said. I agree with everything that you said. Unlike racing, however, a gradual decrease in horsepower for a street car, in the absence of an otherwise compelling reason, would not push me to spend $5,000 + to treat a measurement. I prefer to treat the symptom which, in this case, has not yet declared itself. To be sure, as owners of these machines, we pride ourselves on their perfection. This pride drives us to do crazy things. Your input is well received. Jim S. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 514 Registered: 5-2002 |
Jim, I think that you're right, a lot of owners end up having a lot of maintenance done they don�t need. However, I think the test results do warrant a retest. . I�ve never found it necessary to wait for a catastrophic failure to change a timing belt and I don�t think I would drive much without a second opinion on a failed compression and leak-down test. If they�re lying, which I don�t think they are AND another shop repeats the results after the engine has been run, I would be concerned. I�m pretty sure the factories do follow engines over their life and know what the numbers mean. I did read a consumer report article , maybe 10 years ago, they tested oil by measuring the engine parts, running it 60k mile then remearsuring, so it is done. I know from personal experience racing that poor leak down numbers translate into low hp on the dyno and slower lap times that all return to normal after the engine is serviced (rings, valve job, ect). If the poor leak down is worn rings, it will get worse slowly and doesn�t much matter really, if it�s a bad head gasket or leaking valves, it will ruin the head. The gasket could be tested for by pressurizing #5 or 6 and connecting one manometer to the other and another to any other (maybe 7 or 8) as a control. Leaking valve can often be heard with a scope or felt be pulling the exhaust or intake manifold. If it�s just rings, all the pressure with end up in the crankcase. I agree with you that I wouldn�t pull a head just yet, but I really think that more data is in order. | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 6 Registered: 5-2003 |
Thanks to all. Very sobering thoughts considering the amount of vermouth floating about. Jeeze.. The service dept at Orange County Ferrari agreed with a bit of what I am reading here. I have another issue to get looked at...popping dash light fuse. I will take it to another place and have the compression checked again (hot) and explore the cost of checking the head gasket and replacing if needed. That's it. I don't mind driving it for a year or two as long as I'm not hurting it. It's a 5k mile car. | ||
| James Selevan (Jselevan)
Member Username: Jselevan Post Number: 562 Registered: 6-2002 |
Mark - I understand your concern over the hypothetical. However, if one were to randomly do compression/leak down tests on 100 Ferraris without symptoms, I suspect many would have significant variation. Yet, not that many have catastrophic or otherwise costly failure found at routine service. There are a lot of moving parts, and with 8 or 12 cylinders, variation is likely the norm. The WSM may designate an acceptable deviation from norm, but this is on new engines. I do not know whether the factory has followed vehicles 10k, 20k or more miles and retested. To trust the reports from the field is, well, subject to error as illustrated by the differing opinions about how to do a compression or leak down test. How many people are reading this post? How many miles have we collectively driven over the course of our lifetime? How many have suffered catastrophic or otherwise costly failure that occurred spontaneously - THAT IS, not initiated by, forgive me, "meddling?" I suspect, and forgive me again, that most of the dollars spent by this esteemed collection of hobbyist were required because someone went to a mechanic to get a compression test for no other reason than they were interested, or during a PPI, a compression test revealed a deviation, or during a minor tune-up, a compression test revealed differences. You, undoubtedly, get my point. Perhaps what we are really experiencing is "Pride of Ownership" and our desire to make our obscession "perfect." However, for me, stated in a more articulate and succinct fashion, "If it ain't broken, don't fix it." Again, my minimalist opinion. Jim S. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 513 Registered: 5-2002 |
James, the only thing I would worry about ignoring the problem is the slow deterioration, which is the leak getting worse because the metal is being burned off the head or cylinder and may require resurfacing or replacing a part that that was fine when the problem was discovered. Others, As for my statement of liking to watch the rev to max pressure, I just think it is interesting and occasionally helpful to watch it. The value that I record is the max reading regardless of revs. I tend to do a compression test first because it�s easier and I�m lazy. If all the cylinders are within 5 psi or so and similar rev count, I would probably stop there unless I was looking for something specific. If the rev count was a lot different (say all 3s and a 6) I would do the leak-down just to be sure. I don�t like differences in things that should be the same, although it probably just means I made a mistake � the hose wasn�t sealed, the throttle wasn�t open completely�.. As for reading the directions, the leak-down tester I bought form summit racing says to be sure the engine is cold so you don�t burn yourself and the cylinder is at bottom dead center so the engine won�t turn. I don�t know about anyone else, but I honestly don�t much care if a cylinder leaks or doesn�t cold at BDC where cylinder pressure would be zero anyway. Clearly the lawyers wrote those instructions. | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 44 Registered: 10-2002 |
John... you FOOL!!! How the HELL are you gonna solve that one without martinis... HUH?!?!? Ok... so if JRV didn't rip it off... who DOES have my vermouth???? PS The first F I wrenched was Glen Yarbrough's (of Limelighter's fame) 250 SWB Cal Spyder, which dropped a cluth in front of Boys Town on his way to do a concert in Omaha... circa '66. Like it or not.... you learn a few things over the years. Like when there's no point in arguing Andy | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1522 Registered: 11-2002 |
I'm gonna sign off on this discussion...and I want all you guys that have been doing compression and cylinder leakage tests wrong all these years to feel comfortable in knowing that I don't expect you to admit it...and you're secrets are safe with me.... ;-) | ||
| James Selevan (Jselevan)
Member Username: Jselevan Post Number: 561 Registered: 6-2002 |
Kevin - allow me the contrarian position. First, why was the car at Blackhorse? Was it running poorly? If the car is running well, leave it alone. A difference in leakdown/compression is a objective finding, but if the car is running fine, the only one benefitting by a top-end rebuild is the mechanic. I would fix this, but only if the engine were out for another reason. I (I emphasize my personal opinion) would treat this patient only if the symptoms demanded. If it runs fine, enjoy it until such time as you have other reasons to dive into the engine. As for this leading to bigger and more catastrophic issues, I believe you will witness a slow and non-painful deterioration of performance or idle. I have difficulty extrapolating to a catastrophic demise. One caveat; if the head gasket is leaking, make sure that coolant is not exiting the system, or entering an oil passage. Both of these are usually easy to determine through monitoring of water level (and engine temperature) and by checking the oil dipstick for milk. Merely the thoughts of a minimalist. Jim S. | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1521 Registered: 11-2002 |
Andy, nahhhhh...no vermouth...;-) it just seemed for a second that one of the mysteries of the universe (compression tests) was about to be solved...;-) | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 43 Registered: 10-2002 |
PS to John, You sortta overlooked the second half of that sentence. In full, I said.. "Granted, the leaky one won't show as high on compression testing as if it weren't, BUT IT WON'T NECESSARILY BE OFF BY MUCH." Try it on a leaky engine.. you'll see. So, DID you rip off my vermouth??? Regards, Andy | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 42 Registered: 10-2002 |
John... You rip off my vermouth??? Andy | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1520 Registered: 11-2002 |
>>Granted, the leaky one won't show as high on compression testing as if it weren't, << Andrew...absolutely... and this "won't show as high as a non leaky cylinder" is what a compression test is all about. A compression test is simply a test to determine if other tests are neccesary. And the determinate is low numbers or unacceptable diferentials. Realize compression gauges are never checked against certified testing equipment after we own them...the reason is, their definative accuracy is not the overiding factor of the test...the important info is derived from every cylinder being checked exactly the same with the same tool and decrepencies if any noted. Those descrepencies are what can lead to Further more accurate, more info producing tests...like a cylinder leakage test. Good cylinder leakage tools have 2 gauges on them for areason...the regulator is there to insure that even under different incoming line pressures the exact same amount of pressure can be pumped into each cylinder in turn...you have control of the accuracy of the test, because you have control of the accuracy of the tools through adjustability. Repeatable, Verifiable results....anyone should be able to perform a test and IF the results are quality results, anyone using quality procedures should be able to walk right up and reproduce those same results. That's the importance of double or triple checking all results the end with anomolies, to confirm or deny previous test results. | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 41 Registered: 10-2002 |
John.... Ok... I've said what I had to say, lol... I need a martini. Where the hell's my vermouth?? Regards, Andy | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1519 Registered: 11-2002 |
Hey were making progress here I do believe. The purpose of a compression test is two fold basically. To check for leaks and give some insight into general condition of the sealing ability of cylnder components. On one hand the maximum # is being sought...150-160-170...which gives a general sense of the compression ratio or compression ability....the other # being sought is any differential that may exist between a good cylinder and one not so good, if thats the case. As Craig explains, if there is a leak, that particular cylinder will not be able to compress the air to the same degree a perfectly sealing cylinder will. This general overall condition and any discrepencies is the information that is being sought in order to determine the next step in tuning or repairing an engine. Once the compression information is gathered in the proper way a quality determination can be made as to what next step is appropriate...if there are cylinder # descrepensies that need further investigation a cylinder leakage test would be the natural next step. With the Cylinder Leakage Test one can determine in fact if there is a problem, (if that;s the case) and within certian boundries what the problem may likely be. The reason for two tests is to give insight to the degree possible whether the VALVES or RINGS (or something else)are the problem. Reason being, it does no good to do a valve job or replace a head gasket if the RINGS are the real issue and vice versa it does no good to replace rings if the valves are the problem. As stated originally, the test results are worthless without careful understanding and implementation of the tests. | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 40 Registered: 10-2002 |
Craig, Yes, that's pretty much exactly it. However, my point is that you CAN blow up a balloon with a hole in it... if you blow harder/longer. Regards, Andy | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 39 Registered: 10-2002 |
John, I understand your point, and agreed with it - in the main - in my earlier post, and still do. That IS exactly how a compression tester works. I've seen your website - impressive - and I wouldn't presume to argue with you. However, a compression test measures the ultimate pressure a cylinder is capable of producing, while a leak-down measures how long it can maintain that pressure. A leaky cylinder CAN pump up, given enough "tries". Sorry, but I've seen it many times. Granted, the leaky one won't show as high on compression testing as if it weren't, but it won't necessarily be off by much. If one cylinder can max out in, say, 3 cycles... while another one takes 6 to get there - which I'm sure you've seen - you're saying that doesn't mean anything? That's the difference between compression and leak-down tests. Best regards, Andy | ||
| Craig Dewey (Craigfl)
Member Username: Craigfl Post Number: 600 Registered: 1-2001 |
Andrew, I think what you're trying to say is that if there is a leak in the cylinder, it may take a few cranks for the piston to "catch-up" with the leak before the pressure stabilizes(which is the very reason you should crank until the gage reading steadies). The first few cranks have to compress all the air in the system including the added air from the compression tester hose and gauge. If the leak is large, you may never reach max pressure. Try to blow up a balloon with a hole in it. | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1518 Registered: 11-2002 |
Andrew, here's how a compression gauge works regardless of numbers of cranks. A cylnder, any cylnder is pumping against a spring in the gauge, even if you pump/crank 10 thousand times the quage will only read the amount of pressuse the piston "can produce" 'against' the force of the internal gauge spring....so once the needle reaches "THE amount" of compression a cylnder is producing it stops moving higher because it has force acting against it. A piston "cannot" produce "pressure that acts against the spring if it is "leaking" no matter how many times it cranks or how hard it tries because the Pressure Leaks Out (if there is a leaking problem) and this leaking out information is what is being sought. | ||
| Andrew A. Illes (Andyilles)
New member Username: Andyilles Post Number: 38 Registered: 10-2002 |
John (JRV) -- You're right in that most test equipment instructions say exactly what you posted. However.. think a second. Isn't a leaky cylinder going to take longer to pump up a compression gauge, than one that's tight? In fact, any cylinder that takes more revs to pump up.. bettcha it has a bad leakdown. If you think about it, the revs-to-max and a leakdown are basically showing you the same thing, right? Kevin -- Low readings in adjacent cylinders, as in your case, indicate either a bad head gasket 99% of the time, or a cracked head. Fortunately, it's nearly always just the gasket. I've NEVER seen valve guides result in a low compression or leak-down... they're UPstream!! A worn guide allows the valve to flop around, but it will still seat (and seal). The only POSSIBLE causes of low compression/high leak-down (not necessarily in order) are; a) leaky head gasket; b) burned, etc valves; c) worn/broken rings; d) cracked head; e) burned or punctured piston; f) cracked, etc. cylinder liners. But as I noted before, if there str low readingd in adjacent cylinders, bet on the gasket. Compression tests can be done hot or cold, though hot is better.. but all the posts are absolutely correct about only doing leak-downs hot. All the bits should be fully expanded and seated. Imho, any leakdown in excess of 5% is trouble. But if they did your test cold.. AND told you a compression test wasn't necessary.. well, maybe they should be diagnosing Ryobi weed-whacker engines instead. Notwithstanding that, the compression test confirms the leakdown in your case. You have a problem between those 2 cylinders, and I'd suggest you pull that head and eyeball the head gasket. Andy | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1513 Registered: 11-2002 |
>>I like to watcht the number of revolution it takes to get full presure, it's 3 or 4 in a good engine<< disagree again and so do the links I posted last round... it;s crank until the needle of the compression gauge stops climbing according to the instructions supplied with the gauges, and mutiples of tech articles from experts.. >>I would think that this is engineering fact<< It is and I posted the facts for you, problem is simple...we can teach monkey's to fly in outer space, but we can't teach anyone to listen! Believe it or not, compression gauges and cylnder leakage gauge sets come with a set of instructions on how to properly use them ! | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 512 Registered: 5-2002 |
--140 145 150 160 135 130 150 160-- Ohhh, that's not good news. I would still like to see it retested and make sure the fuel injector are disabled (unplug the injector harness or the fuse on fuel pump) and the throttle is full open. I like to watcht the number of revolution it takes to get full presure, it's 3 or 4 in a good engine. If you get the same result, the head needs to come off, driving with a blown gasket can do bad things to the sealing surfaces over time. | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 5 Registered: 5-2003 |
They gave me the compression check numbers. 140 145 150 160 135 130 150 160 The 135 and 130 numbers represent the cylinders that did poorly on leakdown. This was done barely warm. They started it and pulled it into the garage. In Calif...so the ambient temp was probably 80 degrees. So...I may just drive it. It's annoying as sh*t to not be able to rely on info from (reputable) repair shops. I would think that this is engineering fact. One way to do it. Ha! And look what biz I am in! It's what am I talkin' about! | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 511 Registered: 5-2002 |
--If it's a 95, it could be guides.-- Well, the guides might be bad too, but I don't see how that would cause adjacent cylinder to fail leak down. | ||
| Dave328GTB (Hardtop)
Member Username: Hardtop Post Number: 556 Registered: 1-2002 |
If it's a 95, it could be guides. Dave | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 510 Registered: 5-2002 |
Get it retested anyplace else hot/warm. If the second test comes back the same, it may very well need a head gasketand should be fixed, but it seems unlikely to be guides. | ||
| Steven R. Rochlin (Enjoythemusic)
Member Username: Enjoythemusic Post Number: 447 Registered: 4-2002 |
Kevin, They tested the car COLD???? Run away.... run away fast... like a signal through a nice OTL amplifier. Enjoy the Drive, Steven R. Rochlin PS: will make a BIG BOLD TOPIC on AA citing this thread LOL ;-) See you in San Fran? | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1507 Registered: 11-2002 |
>>What do you guys opine on that????<< second opinion time imo. Monaco Motors 818-704-1836 Wade Lennon there was a Boxer diagnoised with burnt valves from these same guys not all that long ago, at my urging a second and third opinion was sought (the owner mentioned the first opinion to the second guy, but wised up and simply ask for a comp. test from the third guy ;-)) and it turned out the valves weren't burnt after all. The actual problem was found saving the owner big $$$$. | ||
| Frank Parker (Parkerfe)
Intermediate Member Username: Parkerfe Post Number: 2325 Registered: 9-2001 |
Kevin, I'm no mechanic but even I know that both a compression and leakdown test needs to be performed with a properly warmed up engine. It sounds like Blackhorse is trying to drum-up a little business. | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 4 Registered: 5-2003 |
Forgot to mention...they said it's always valve guides at Black Horse. What do you guys opine on that???? | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 3 Registered: 5-2003 |
••••.... Called Black Horse...he stated that the car was cold when they did the leakdown...and that is the way to do it. In their opinion. Problem is all these mechanics give me a different story or opinion. It's frickin' amazing. Hey Steve R.!! Don't tell anybody I have this thing...I will be a sh*t on audio asylum too! | ||
| Steven R. Rochlin (Enjoythemusic)
Member Username: Enjoythemusic Post Number: 444 Registered: 4-2002 |
Kevin, Yes, could be gasket my friend and cheap enough to try. 30% and 20% down sounds like a BAD situation and i would take care of it ASAP. Engine rebuilding due to severe failure is no walk in the park as a DIY guy... and dare i remind you of the costs? A pair of NOS WE300Bs AINT gonna cut it! Enjoy the Drive, Steven R. Rochlin PS: FYI: mine are within about 1-2% except for one that is around 4% and i am not happy about 4%(!). | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 2 Registered: 5-2003 |
I did a search before posting...thanks guys....I just want to get the most info as it is a pain to get it there for service. And thanks for the thought on the head gasket. Did not think of that. It would also show up on the compression check too? Others concur it could be that? I can ask the same shop to do the comp test. I don't know that they will "fudge" to re-enforce their position on the leakdown. They have a good reputation. | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1503 Registered: 11-2002 |
>>They did not do a compression test, stating it was not necessary. The leakdown tells all. I will have another shop do a compression test to see if the info matches for dropped compression. << Oh Boy...as Mark mentions we've gone over (argued) this at lenght on several occasions. If one does a search, I provided links in the previous discussion validating all my points and procedures. But it's such an important subject and so much disinformation floating around it's relivant to revisit. There are seberal things that make or break these tests. The quality of the tools used and the knowledge, experience and quality standards employed by the tester. Bad Tools, Bad Procedures, Bad Test Personel can render these tests useless. The "proper" procedure would be something like this: Warm Engine enough to clean and seat internal pieces...but not so hot you can't work on it. The only test I know of that requires burning yourself is touching a hot stove. 1- Remove plugs and "check compression", record readings. A difference of 15-20 lbs or approx. 10%-15% between any two cylnders highest to loweset "can possibly" indicate something is out of line with normal. A recheck of the low cylnder/s after the first run through is advised. A perfect normal compression test should render readings within appox. 5 lbs of each other across the board. Perfect and normal being good engine, good tools, good test personel. 2- If compression was suspect or one simply wants a more revealing test performed a "Cylnder Leakage Test" is required. This test is much different and much more difficult to perform 'properly' as each piston must be right on TDC to get accurate readings, as well as quality tools and adequate compressed air supply. Compressed air is pumped into each cylnder in turn at TDC and the amount of air escaping is read as a percentage. Readings above 10% leakage (on street engines/5% on race engines) are considered to indicate the presence of something not holding a good quality seal. In the case of readings over 10% it is neccesary to find the route the escaping air is taking to indentify the "possible" cause or nature of the problem. Leaks of 25%-30% and up will make a large noise of escaping air. A mechanics stethescope with the probe removed (just the ear pieces & hose) are used in the intake, exhaust and crankcase to try and define where the air is coming and thereby lending some info as to what is allowing the air to escape, ie: valves, rings, etc. These tests are very fallible if lax quality control is used. And all anomolies require double, triple or even quadruple checking to insure accurate test results and provide quality, definative answers. A quality test is one of "repeatable", "verifiable" "results". Additionally unless the engine has drastic running or oil burning problems these tests are generally indicative of "long term" issues. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 590 Registered: 11-2002 |
If it's just low between the two cylinders, your looking at a head gasket problem, which should be fixed post-haste. If it's the whole engine getting tired, or even more one bank than the other, then you have more time. BTW, I'd still run a road car with 18% leak. Race car? Then I'd be preparing the owner for top end work soon. This much leakage will begin to make idling difficult, posible other drivability problems. Your solution depends on how long you want to keep the car. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 589 Registered: 11-2002 |
I do both, though prefer leakdown. Normally, I do just the leakdown, and if I discover something like 30% leakage, compression test next to obtain more info before tearing into things. I agree with Mark, too. Sometime one gets a piece of carbon to hang open a valve temporarily, which of course skews the test results. On race motors, if I got 20% leak on a relatively fresh top end, I'd hit the valve with a plastic mallet to try to dislodge the carbon and redo the test. I know this is more difficult for a Ferrari to try. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 508 Registered: 5-2002 |
There have been a couple threads on this topic, mostly relating to PPI, so a seach might be in order. The gist is though that if the test is done on a hot engine, it means something is probably wrong. If the engine was cold, it is not unusual to see 20-30% in a healthy engine. If it is truely leaking that much (hot) a compression test will confirm the problem. If it seems to run well, that discounts the leak-down, because it really shouldn't with that kind of leak. My engine (although a 308), if tested cold give everywhere from 0-30% (I almost had a heart attack the first time I saw that), when retested hot gives 0-0.5%. | ||
| Kevin Deal (Tube_guy)
New member Username: Tube_guy Post Number: 1 Registered: 5-2003 |
Have my 97 355 in at Blackhorse in Los Angeles, and they state cylinder 5 is down 30% and 6 is down 20% on the leakdown, and that they ran it twice to make sure. Car is super low miles at about 5k. They did not do a compression test, stating it was not necessary. The leakdown tells all. I will have another shop do a compression test to see if the info matches for dropped compression. They stated I may stand a small chance of damage at some point. I guess I should wait to see if it fouls a plug? To thicken the plot, a mechanic Ferrari of Orange County stated they do not rely on leakdowns too much. I need a compression check. And that people come in convinced of problems and pay bucks to fix problems that don't exist. |