Different new oil, film break down at a specific operating point (hot cranking) resulting in chatter (chirps).
Hi John, that's right in conjunction with poor oil feed to the cam due to possible obstruction. Oil feed suspect on the video, I think, but will varify with a tool I'm making. Well that's the horse I'm backing at the moment, I have to take it step by step or else I'll drive everybody mad and confuse things. ;-)
And here is my oil flow/pressure varification tool X2.......made from an old nylon rolling pin, ha ha. This little fella is gonna kick ass and must 'check' for engine builders eveywhere.. Just pop them in the camshaft journals, crank the engine and varify the pressure and oil flow, simple. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Hi Matey, just finishing off making the tool tonight. I may run the test but most likely tomorrow, when the light is good. Will keep you posted, all the best Bell.
Interesting. Your conclusion that it's due to lesser quality materials than, say the Lotus, may have some merit but I have no idea. I tend to think the car had an oiling issue at some point - junk in the oil, no oil pressure, etc which caused the wear you are seeing BUT that's just speculation on my part based on other (non-Ferrari) engines I have worked on and subsequent wear patterns caused by insufficient oil in similar applications - valve lifters in US V8s, for example. I have seen that sort of galling on lifters that were oil-starved due to some sort of failure of the oiling system - to include silicone clogging. I would assume if it really is just "normal" mileage wear as you suggest, then folks that work on these cars, and have since they were in production, like RifleD, would have seen the problem and know it to be a "normal" thing after X miles. I have not heard that to be the case but, I don't know if anyone has asked before.
I really hope that is the story however it would be fairly reasonable to then say "well if that's normal wear for x number of miles then why aren't all of them making noise?" Or at least a few of them. And why has no one noticed this noise before as the warning sound if an impending top end rebuild? Perhaps it was a combination of wear as seen on the other buckets with a isolated oil event on that one. It will be interesting to see or hear actually if after honing or replacing the bucket the sound goes away. I can tell you that my engine with 100,000 at least miles had no such sound prior to rebuilding. Loved your test apparatus by the way. Give it a name and apply for a patent!
Bell, Apples and Oranges to the Lotus. Ferrari engines are race engines, to expect them to go 100k without wear is asking something of the engine that's not possible for it. the tolerances are very tight, that comes with a price - faster wear. As to the wear on the bucket that is most likely making noise, not normal. The noise you have is not normal, heck I can't ever think of hearing that noise from a high millage engine. The sound is indicative of a problem, exactly what? well as we've all seen that's the $64k question! Rifledriver has been around these engines since they rolled off the assy line new, if he'd seen anything like that or if it was a common high wear millage issue he would have mentioned it. I know for a fact he's seen and torn apart/rebuilt more of those engines then I'll ever see, I kinda feel bad for him I no longer do service on Ferrari's instead I spend my time finding ways to break them and then improve them based on were and why it failed, utilizing my background in engineering with FMEA. I wish I had a crystal ball and could tell you exactly the issue. The only fault I have with the heads is the poor flow due to geometric layout and the heavy bucket/shim setup. As you've no doubt noticed the bucket to bore tolerance is tight, 0.04mm dia or 0.0015" The lotus Esprit- easiest manual to locate quickly- is very similar with 0.05mm or 0.0019" Here's the difference though, for the lotus dia of ~1.2" a gap of 0.0019 is a class IV transitional fit, the 308/328's ~1.4" a gap of .0015" is below the min for the same class of fit, but too big for class V. all this boils down to that something as big as 100um can cause issues. I've got over a hundred tappet buckets, out of them only 1 showed marring and that was due to it being cracked. your bucket may not be cracked but something isn't right. since you have a lath you can check the radial run-out on it. Another thought is that the shim may be causing the problem, does the shim/bucket rotate as the cam operates? if not that then the valve stem tip or pad under the tappet bucket.
Quote: Bell, Apples and Oranges to the Lotus. Ferrari engines are race engines, to expect them to go 100k without wear is asking something of the engine that's not possible for it. the tolerances are very tight, that comes with a price - faster wear. Yes that is indeed true and I totally accept that. ;-) 'The light that burns twice as bright burns half as long.' Actually the Lotus is a race engine too and like to like develops more power than the Ferrari, they are some era cars also, anyway I'm side tracking ha ha. Would you say that the wear, not the chatter marks, just the wear is normal for a 50,000-70,000 mile follower? What do all the ones you have removed look like, and do you document wear rates at all? Many thanks Bell. Mike, Crowndog you are both right I think and would expect to have other folks with similar issues at high milages too. Question: How many owners have high mile cars ie 60,000+ and how many have had rebuilds or 'head work' at this milage? Smg2 has hundreds of valve followers out of cars, they were removed for a reason....... If I look at all of my followers (not the scored one) they are all worn looking, but not in a 'sudden oil loss way' they just look worn over a period of time. They look like followers that have done 100,000 miles BUT looking at the bores in the engine I know this is not the case, there is still honing on the thrust line. So it's not like the car has phoney milage, I just feel that these cars may suffer wear like this as nornal, then eventually maybe with an oil that is not quite right or some other factor they start to give problems.
A quick note, the removed tappets are not due to wear but a change to shim under for the bigger cam builds. Unfortunatly I have not tracked wear rates on the tappets, from low milage i.e 30k to higer milage 90k the wear all looks the same. Something going wrong is what it usually takes to show excessive wear or damage.
Oh, so cam follower changes are result of engine mods, ok cool. Well I have 3 avenues to explore regarding this wear issue. 1. Is Ferrari here where I live, but they are not old school and may not know much. 2. Bugatti, Ferrari + other vintages restoration shop, they created a Bugatti Royale that's doing the circuit from just the plans! Yes it's a recreation but what a job they did. They are seriously old school and the old boys there wrote the bible..... 3. I have good connections in an oil research facility near me. They test their product against other leading brands, they do back to back testing with identicle cars driven in groups at the same time and then they get stripped at 100,000 miles under lab conditions. Years ago I used to go down there and sneak a peak at the results, it's amazing how oils vary. These days I am right out of date and the loop. So why not change the oil? Well the wear is there and it's a problem there is no denying that, it's now too late. I think putting in new followers will totally solve the problem now, of that I am convinced. BUT, I want to learn more and chart a stage pattern of events here and that is why I'm digging around so stubbornly. I will find an answer, one way or the other, I like to have a proof, or as they say in America, a smoking gun..... Oh and finally here is a picture of the Lotus Excel SE motor, not bad for a 1980s road car, vernier pullies are non standard, but the rest is stock. I love the external oil pump and seperate cam housings, very race engine for quick servicing and easy dismantle. Image Unavailable, Please Login
Bell, I am not sure if you will find the root cause on this one at this stage to be honest. I think I would just put in a new one for now and follow the wear after 5000 miles for 2 or 3 times. Nice tool btw eminently better then MacGyver!
Well Guys, here is the latest. I have been last week to 4 of the top people in the country regarding this issue. The places I visited are not modern main dealers but really old school concerns who maintain a vast range of ferrari cars many of which are historic racers worth millions each. I've also visited the specialist engineering firms they use and on each occasion they have very generously given me nearly an hour of there time. Nearly all of my visits has resulted in a small group of technicians all watching my various videos on my portable player, looking at the followers etc. The result being that after many avenues were explored, no conclusion could be found and or even the source of the noise. 3 out of the 4 felt the the follower wear was normal for a highish milage engine and that the followers were not at all out of spec. Also all of them felt that the oil was not a factor other than in one case it was suggested that it may of acted as a. flushing agent and dislodged some debris. I repeat that none seemed concerned by the wear on the followers not even the scoring on that one follower. In all cases many felt that the noise would show more scoring if indeed it was a follower. So it looks like I'm just gonna have to keep digging on this one. I think that the marking on that follower now might be a symptom rather than a cause. Putting in 2 new followers and running the engine will confirm this I think. And whilst none of the experts can think of how a valve might make a noise like this, it would seem to me that this is now the next place to look. The saga continues damn it!....
Still think vac leak is likely. Just curious as to your injector bushes in the video. These dont look the same as 328 ones although I would have expected them to be. They dont appear to be pushed right in. On the 328 they are right inside and retained with a circlip.
Engine noises 101: http://www.southernwheels.com/Dec-08.htm So then I had an idea. Could you use a timing light to locate the offending cylinder with it's associated valve train event? When the flash and sound occur together that would be the compression stroke for that cylinder correct? Not totally sure how this could be useful but may provide another data point.
Hi Andy, just to recap it does do it with the plugs out so no compression at all. Also sound is through the bearing cap area on no.4 Hi Crowndog, just to recap, it is a cam timed event located in the exhaust no.4 area. The plan is to change out those 2 followers, run it and go from there. All the best, Bell
I had a thought, take the shims on both tappets of exhaust #4, use a sharpie and 'paint' them over. install and turn the motor by hand a couple times, look and see the pattern as it wipes away the marker ink. I had an engine assy last yr that had a couple not turning, I had reamed the cam journal bores but the problem persisted on one bore, ended up having to heat and flatten the heads straight again, then ream the journals. That fixed the issue, now if it that was going to cause noise like you have? not a clue. pics.. Image Unavailable, Please Login
Interesting. The thought of the head being warped --- more specifically, distorting slightly in that area when warmed up --- enough to cause the shaft to bind and "squeak" against the journal locally..... crossed my mind a while back. But, I did not mention it as I thought it was more likely to be something more simple. Also, could be that the head is only distorting because the head bolts are loose (under-torqued) locally. Might not be a bad idea to check / re-torque them while the cover is off ---- just in case. Another wild thought...... What if one or both of the shims (on the #4 cylinder) has far too much clearance in the bucket recess ---- meaning that the shim's OD is sufficiently smaller than the recess' ID, so that the edge gap is large enough to allow the shim to slide back and forth substantially against the contact surface of the bucket ? Not much, if any, oil would ever get in between the two to reduce friction, so given the right set of pressures and movements..... perhaps this could produce an audible "squeak" ?? Also what if the shim(s) is substantially distorted (not flat and perhaps even center-crowned) so that it is being flexed every time the cam tip pushes it ---- like a diaphragm spring ? ...... just a couple of last Parthian shots....
Hi Smg2, you know that is a check I haven't done, I will check they are turning, cheers ;-) Hi Finnerty, just to say that the noise persists even if cam caps are individually loosened and engine is cranked also there is no pickup in the cam caps so the load is even making a tough case for warping...... possibly. Here are some pics and thoughts.....also some light honing of the followers.. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Hey Bell, thanks for sharing this with us, I like your video clips, cool to see the engine and all the details you're looking at. hope you sort her soon. Rgds Johnny
Cheers Johnny, Crowndog, Guys gaskets and 2 new followers arrive today, I'm going to measure the old ones to the new and see if I'm happy keeping the old or changing them all out. Obviously just changing them all is not going to track the problem which is what I want to do first. All the best, Bell
I want to offer a bit of advice, if you have a micrometer use that to measure the tappet bucket dia. dial calipers are decent for quick checking but lack the repeatability and accuracy of mic's, they're also 'springy' on thin parts. Just a fiddly point that was driven into me by my dad who was a tool and die maker.
