308 Cam Belt broke..... anyone wanna help

Isn't the 308 engine an "interference fit" engine? Meaning: do not the pistons hit the valves if the timing belt snaps? Seems to me that there would be more damage. You may have gotten off easy. I see that you only have ONE posting. There are a ton of guys on this site that can offer mountains of suggestions on any problem. Do not dispair.

 

Its an interference engine. Bent valve at least and really, there is nothing wrong with a couple of smile marks on the pistons where the valves touched. Redo the front cylinder head and put it back together, it wouldnt be the first time thats happened.

 

Spirot, stay tuned and have faith. It has been discussed many, many times whether or not a belt will actually break if not done before the 3-5 year window. After others chime in with the standard "I told you so's" you will get some solid advice and help. This will also help lay to rest the notion that cam belts/will not will break.

For heavans sake DO NOT TURN THE MOTOR OVER ANYMORE. You could be making your situation exponentially worse. Pull the valve covers and turn over slowly by hand if you must confirm your diagnosis.

PM me if no one else chimes in (even though my experience is with 12 cylenders)

 

Tom?
Email me when you have a chance, I may be up for some wrench turning.

 

i wonder where are all the people here who say they've never heard of a timing belt breaking

where are they now
MIA like usual



hope you get it all fixed up

best of luck

 

I'm one of those people and I am very interested in this thread. Please let us know how much damage was done and the possible cause of the failure.

 

I am also one of those people....

Believe me that I am paranoid about mine breaking, but I have never heard of it happening on a Ferrari. The only car I have heard about it happening with is an Acura Integra. But that was probably because the owner raced the HECK out of it constantly....

 

Hello from Germany,

I'm on of those too.
I admit this won't help, but premature total cambelt failure IS unusual and there must be a reason. I suspect that either something was going wrong while the cambelts were installed or while they were shipped or stocked. Sharp bending is the deadly enemy of cambelts.
Or something went wrong with the tensioner bearing, tensioner bearing support or the early plastic pulleys.

Best Regards

Martin

 

If the description of the failure is accurate, and no 'bang' or other loud noise was heard, then perhaps there was no significant piston/valve collision. If there wasn't, is this really all that bad?

 

Spirot!

I am SO so sorry to hear this. And at such a bad time. If I were anywhere near you, I would seriously come over and help. Seriously, if you dont BS around, and you work on it like its a Fiat, you can have that motor on the garage floor in a day. Taking the one head off is pretty fast, and if all you did was bend a couple valves, say $200 for valves, $200 for a head gasket, say another $200 for miscelaneous stuff, and for less than a grand you could be back down the road. Just resist all of that "while im in there" crap, and go at it like a dealer would. One week my man, one week. Dont go giving up the ship till she runs, or you will lose a good $20K of your investment. Please, you have owned this car this long, you can do this. And maybe after you will have enough confidence to work on the car yourself and save all those $$$.

As for all those naysayers out there who claim these cars wont break a belt, I am sure many will remain silent. A month from now some idiot will ask why the belts need changing at such short intervals. BECAUSE THEY WORK SO FRICKEN HARD, THATS WHY! And stop comparing it to a Honda or a Toyots, its not a JAP car. I think all of those who argued for longer belt change intervals should be forced to pay Spirot $200 each as repentance for your sins. But wow, maybe now we need semi annual belt replacements? Be interesting to see what brand tensioners you have in that car. FOA wouldnt have put lesser quality ones in would they? See if you can feel one and if they are bad.

I dont know about anyone in the area down there, but I seriously would take a couple weekends and help him if he lived near me.

Carry on, gentlemen

 

I agree that you shouldn't panic and you can do this yourself; try and get some help though as timing the valvetrain is something you want to get right the first time!

Also, the "while you're in there" thing isn't always the first sign of shipwright's disease! At least consider a water pump rebuild.

Ken

 

I hope for the best, but I know what you will find:
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i broke mine on my mondial t (several years ago)

keep in mind it has only 1 belt (348 engine) so when it breaks you bend valves on BOTH heads

i bought the car (in my naive days) from a seller who said "oh yeah, it's been major serviced....i just need to find the paperwork"

guess what, he lied

hard lesson learned

 

First things first. Locate a leakdown guage and check for bent valves. Set the cam timing as you were going to install the belts and set the engine at top dead center. If the tech that looked at this is sure it broke at TDC you are one lucky dude because you may not have bent valves. Line up your timing marks and perform a leakdown test. With 100# pumped into the cylinder, if you see 90# holding or better, you are OK. Procede with replacing the belts and tensioner bearings. If you see numbers much lower than this, listen to hear where the air is escaping. If you hear it hissing out the exhaust, you have bent exhaust valves. If you hear it hissing back through the intake (remove the plenum hose), you have bent intake valves. If you hear it hissing through the removed oil cap, you may have holed a piston and it's time to pull the engine. This is assuming the leak down numbers are low. If they are above 85%, you are probably fine. I would expect 90% or above, being that the engine was recently overhauled.

Good luck. Feel free to PM me and ask any questions.

John

 

Krowbar - There is a sense of "I told you so..." in your post, which of course, is well deserved.

HOWEVER, There are other failure modes that do not include a failed belt. Let's see what is found upon disassembly.

AND, based on your (appropriate) advice concerning a ...just the facts, ma'am, just the facts... approach to fixing the thing for $1000, then I will maintain my economic position that it makes more sense to take a chance, drive the car for 60k or 100k miles (indefinite time frame) and fix it if it breaks.

I will be WAY ahead economically. One cannot get away with a major at a dealer for $5,000, while fixing a belt and a few valves costs $1000 (double it to be sure - $2,000) when performed out of frustration and economic need.

Still sounds like an unusual occurence (if it happened - we shall see), and the economics point towards a non-major approach.

My thoughts -

Jim S.

 

sounds like an avoidable situation but not a disastrous one....

 

Krowbar's estimate is unachievable if this thing DID bend valves. Keep in mind it's a 4V car. If valves are bent, it will need guide work and possibly seats, and that's assuming the valve face didn't snap off and is now imbedded in the top of the piston. It could be ugly. The breaking belts is better than replacing belts argument is absolutely rediculous, but it's your money, have fun. You can do belts and tensioners for about $700 and a days labor. You will NEVER fix a 308 with bent valves for twice that much, even a 2 valve car.

Do a leak down and diagnose the car properly. Until then it's just speculation anyway.

John

 

I have not heard of a belt failing while a car was moving at 30 MPH. The belt failures I have heard about all have occurred at idle? I would be interested in hearing about experiences from others. It makes sense too because there is the least rotating momentum at idle.
When my belt "failed" in another car the belt didn't break, the teeth just ground off on the smaller crakshaft pulley (see picture). Have other belts broke or have the teeth been ground-off?

Mark
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This all brings about the question: Why didn't Ferrari just continue to use chains instead of belts and avoid this ongoing problem? Chains DO get loose and jump timing but it happens far less frequently and less disasterously than a broken belt. Why doesn't somebody just design a chain conversion? Could it be done?

 

Chains require more power to move than do belts. Or to put it another way, a small % of the engine's power is going to move the chains. If you have belts that power is being delivered to the flywheel.

 

Chains are also a lot noisier.

We killed the 3x8 chain conversion alternative a while back in one of the belt threads. Search for threads w/'belt' in the title.

I'm very interested in what the failure was.

re:

The above confuses me. You can see the REAR intake cam thru the oil filler cap, not a front cam. Which belt do you believe is broken?