Got the motor out, this is the picture of the timing belt

TDC can be located by removing the sparkplugs and using the hole with a dowel to locate when the piston stops moving, if you can wiggle the crank back and forth with out the piston moving you're at TDC. most times the force of the air wont work against the piston to move it off of TDC but to be sure you can keep the crank from turning by putting it in gear and setting the parking brake. if it moves off of TDC the cylinder volume will change and screw up the result. most engines only need 100psi in the cylinder to calculate the loss.

 

The simple way is to remove the spark plugs,you have to anyways,and then get a long screw driver that fits down the plug hole and then slowly turn the engine over by hand(using a socket and breaker bar on the front of the engine)till the you can feel and see the piston coming up to TDC. Turn the engine over till you feel/see the screw driver stop coming up. Thats the easy way. And should be close enough to conduct the test. I cant remember if it was mentioned on here if there was a timing mark on the crank and timing case cover to also double check the TDC?
To lock the engine,you can just use to breaker bar on the front of the engine to hold it at TDC,as it shouldnt(but can) move once you do the test. Thats about the only way i can think of on this engine. Unless someone can give us more ideas? On an engine where the flywheel is at the back of the engine,we use a flywheel locking tool,that latches onto the flywheel teeth,and it has a big handle on it which makes it easy to hold the engine if need be.

 

You don't need it at TDC. You are not looking for perfection in the test, you are looking for leaking valves and they will be closed no matter what position the crank is in if the cams are out. Pressurize the cylinder and look for air leakage from the intake and exhaust ports.

If you are set on doing a complete major overhaul on the motor don't bother just take it apart and replace everything. The 4 valve motor series is so good however you may just want to fix what is broken and doing that test will give you a lot to go on.

I just did the same on a TR with 30 K miles and a broken belt. Saved me a lot of time doing tear down and inspection looking for parts that are not broken. Also will save the owner $$$.

 

Thats the way to do it also,but the engine is removed from the car in this case.

 

Who cares???

The cams are out.

The valves are closed no matter where the crank is.

 

Hehe,i guess you're right Brian. Just doin it to check for bent valves. Maybe im just a perfectionist....

 

Special tool-I sent a pic in earlier thread. Looks like an offset box 15 cut a couple of inches long with a 1/2" drive extension welded on.

 

well here's where i would be slighty concerned. load, is a static load of 100psi going to cause any trouble for the conrods at that angle if lets say the cylinder is near BDC? the spark for ignition and full compression occurs near TDC where the rod is in a near vertical arangement and the load is engineered for, at the bottom of the stroke the rod is angled and the load is going to cause stress issues. now i do relize this is a static test and not a dynamic one. then again maybe i'm overly concerned, who knows. anyhow it's the engineer in me that makes me do these things.

 

100 PSI??

Might as well fart in the cylinder for all the stress either will cause.

 

brian you have such away with words the 100psi is generic, what's the normal testing Psi? and would that pressure be stress on a conrod that is not near vertical, i.e. mid/bottom stroke?

 

60-100lbs and neither comes anywhere near the pressure that is exerted when the cylinder fires. A cranking compression test generates 1 1/2-2 x that amount of pressure and we still have not introduced an explosive gas mixture and a spark.

 

brian i'm not questioning your work or results in the least. i'm one of those 'nerdy' types that loves to run calcs to 'see' just what is going on, the why if you will. these discussions are always interesting, as an engineer i see the numbers and calcs, and brian the 'field' engineer sees the real world. two sides of the same coin.
quick and dirty...
the force on the cylinder after spark is about 2~4klbs however that occurs at just about TDC, when the cylinder drops to BDC the volume has expanded and thus pressures drop considerably. the combustion comnsumes the energy in the compression and converts (some of)it to heat, the volume of air that is now occuping a much smaller space is ignited and forced to expand in an instant to it's original low energy state, pressure is lost due to thermodynamics. the valve train as we know opens and closes thus allowing the air to escape or enter. at BDC to TDC on the compression stroke the force of full compression is not relized until TDC when you get to the quench area. so what this works out to is that all the force a piston is put thru occurs at TDC same goes for the rods. now is a compression leak down test going to cause harm if the cylinder isn't at TDC? probably not, but i'm not 100% sure since the rod doesn't experiance those forces at that angle. this is another reason why rods fail under boost, the increased chamber pressures stress the rods under side loads.
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Conrods never get a side load. They have only two points of contact... the big end and the small end. Just because the piston is half way up the bore... it doesn't push sideways.... the PISTON gets a load against the bore, but the rod is ALWAYS compressed upon it axis between centres.

 

the piston moves in a fixed plane and the crank revolves as such the conrod will experience loads not only on the two ends but offset of thier respective planes. under normal operation the load is transmitted when both ends are near vertical in plane but if you load the piston while it is in mid stroke the rod will bend due to the load being transmitted off of the rods axis. i've seen many an 'S' bent rod.

 

Rifledriver (Brian) is correct-100 PSI will mean nothing to the Con-Rod. Just do the math--100 lbs per square inch pressure applied over the piston top face, which is what, about 3.0 to 4.0 inches wide? Take the worst case-4 inches, which is probably too wide for this piston (I don't know and don't care.) Then the surface area of the piston is (4.0^2 X (Pi))/4 or 12.5ish square inches. Thus the force applied to the conecting rod is: 100 X 12.5 or 1256 ish lbs force. So say about 1000 lbs load-not really a lot.

 

Sorry SMG2 it is physically impossible for a rod to accept anything put pure internal axial loads from the piston. The connecting rod has a pivot joint on each end that makes it impossible to resolve out any bending moments applied to it. If you put a side load into a connecting rod it is resolved out by the piston skirt to cylinder liner and/or the crank journal. Now this does not mean a rod cannot bend. But it will only bend if the ability to rotate at either end is removed, usually by some other failure mechanism.

 

my appologies i should have been specific, yes from just the piston itself no, but if the crank was exerting force oposite the piston force or if you kept the crank from turning it would put that stress into effect. i was merly going on the assumtion of the crank not moving and filling the cylinder with 100psi.

 

I own a 90 348 and have been reading this site the last few days. One thing I might add is finding TDC w/a dial indicator. I remember using the stick method on dirt bikes when I was 15, crude but it works. My 348 has 14k miles on it, and did the belt year and a half ago. 14 years old and it was loose and floppy when I took it apart. I got it in 1999, drove it 500 miles (in retrospect dumb) and parked it. Well, the belt job certainly opened my eyes. Turns out the engine cradle had the left top shock tower pushed in 2 inches and pulled out. When you whack the lr, a triangular support pivots at the bottom and the top moves the upper control pivot support tubes forward. Someone fixed the body and frame, but vertical tubes in slight 'S' shape measured w/a straightedge, resulting in lr upper pivot points to be off, not good. Bottom line, new spider engine carriage from Ferrari of Houston, 2 new l control arms, others bent, new sway bar bracket, and the belt job turned into a 5 year project, lol. Actually 2 weeks work, coupla years wait for frame, coupla years doing other things.. In the process measured tub a bazillion times to make sure it was undamaged. All together November 04 and still only drove it 100 miles since. I have pics from the whole affair, and can say that car has almost zero setback and fixed right this time. So I guess I get the dubious award for most repair time verses drive time. Been getting back into it lately, pedals, slickshift, desticky, hyperflows, x-ost and looking for 355 wheels as next step. Last year have restored 7 vintage dirt bikes. Still have 2 Maicos and 2 Huskys to do this summer. Bottom line, on my own stuff, I just tear it all down and inspect everything. Crazy, but you end up w/a job done the right way that only you could do. Either that, or a shop woulda charged me 15k and done it w/o the loving care it deserves. I did paint the carriage high gloss black frame paint. I don't like the gooey black textured coating, and since frame came just primered, I wanted clean and shiney hot rod look, sorry purists. One piece I need is the shifting cable cover under the tranny, about 12 inches by 5 inches? Sorry for rambling!

 

I think that it's human nature to start projects that drag on or don't get finished at all, with fewer exceptions than you might think.

When I go out to the airport, there are always the same 15 or 20 hangar rats pretending that they are each going to finish their 15 or 20 year long aircraft restoration projects.

Won't happen. Maybe one will get an old bird back in the air before he dies, the rest won't. They'll have 5 to 6 figures in new parts laying around that their heirs will sell for pennies because it all looks like a pile of rubbish when it's all torn apart.

But they'll all talk a good game about finishing each one. I guess that's what they really want, just to talk and tinker.

 

Not only wont 100 psi hurt the motor near BDC, it wont hurt it no matter where its at. Think about screwed up ignition timing with backfires, or preignition on shut down, your motor dont just explode. It wont matter where the motor is, if you apply air to the spark plug hole the motor will roll over to BDC on that cylinder. Brian is also correct, you dont even need a tester, just a compression tester hose that fits the air chuck on your airline. Apply line pressure and listen for air leaks. If the valve's bent youll hear a lot of air coming out the intake manifold, or the exhaust ports and you can just keep taking the motor apart.

 

I would do the leakdown test for sure. May save alot of $$$. I think the metal in the oil is the disintegrated balls from the tensioner bearing. This metal would be stopped by the filter, the oil pump would be the only part of the system to be subjected to these fragments without filtration. I'm not sure if there is an inlet screen for the oil pump. If there is a screen it may have stopped most of the fragments from getting to the pump. One more observation on the leakdown test. The connecting rods are vertical at both TDC and BDC. If you get the piston at exactly TDC, it will remain there as the piston and rod have no leverage against the crank journal when the piston and rod are exactly aligned with the center line of the crank journals. Some USA built engines have offset piston pins (making the above mentioned alignment harder to accomplish). If I remember correctly, this feature was designed to make for a quieter running engine. I wouldn't think this feature would be included in the design of a Ferrari engine, but I couldn't say for sure. As was stated above, pressurizing the cylinders with the camshafts removed with just an air line will tell you whether any serious damage has been done and where.

 

Do they have a service limit...like 30k miles? Or are they time dependant like the belt? Seems equal wear if one redline shifts for 10k miles or drives like granny and keeps engine below 3000 for 30k miles. Also, they spin faster than the crank inversely proportional to the diameter ratio, like 15k rpm? So redline for an hour is almost a million revolutions! So do they burn up at 200 million revs? Inquiring minds want to know. Thankx. Doh, idler looks close to crank pulley size, cam pulleys twice as large(4 cycle)

 

This is an unfortunate thing. However, doing anything other than a rebuild is not wise. Is this an interference engine? If so the question is how many valves, not if any were damaged.

If you don't do a proper repair you are likely to do a more extensive repair later, if the motor will run at all.

An important question someone alluded to above is if you will ever finish the project if you take the motor apart. The motor is still in one piece now and this is a great time to take it to a shop and have them rebuild it.