Timing belt broke. Interference Engine. Screwed?

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Not my car. Coworker’s car. 2004 Saturn L300 V6. The V6 is an interference engine. The engine just cut out while driving down city roads. Coworker had it towed to a shop. Mechanic said at first the problem was just the serpentine belt. I found that odd. I don’t think a serpentine belt would cause a car to die suddenly while driving.

2 weeks later the mechanic tells my coworker the timing belt looks bad also. So he is going to replace that. The mechanic acknowledges the engine is an interference engine, but says he cannot verify if the engine is destroyed until he replaces the timing belt so he can check for compression. Does that seem right? Could the engine have survived really if the timing belt broke or maybe just slipped? Is there no way to verify the engine’s condition without installing a new timing belt?
 
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Well, IDK if there is a way to check that the valve(s) haven't clashed with the piston(s) without removing the head(s). However, I do know of instances where the timing belt has snapped on interference engines and all was OK.
 
Sounds right to me. There is a slight possibility it’s ok though. My mechanic once had an Xterra come in with a broken timing belt (interference engine) and it ran fine after a replacement.
 
Originally Posted By: Char Baby
Well, IDK if there is a way to check that the valve(s) haven't clashed with the piston(s) without removing the head(s). However, I do know of instances where the timing belt has snapped on interference engines and all was OK.
Sure-a compression test will show any bent valves. But, when in doubt, change the timing belt, don't ask me how I know!
 
Luck of the draw on an interference engine. If it won't turn over then you'd know it's messed up, but if it turns over and seems OK, then it would have to get a timing belt on it to do a compression and/or leak down test.
 
put a scope down spark plug holes.

takes almost no time and might show severe issues.

honestly its probably junk and not worth fixing 80+% of the time.
 
In case if a timing belt jump, it can damage valves. Had an instant with 7th Gen Civic, now breaking a timing belt means definitely valves are bent, possibly quiet a few.

If it's not turning over while cranking, definitely (some valves) or head needs to be be replaced. We took the route of a re-manufactured/machined head, it was rather cheap option.

Good luck.
 
Yeah there are cheap chineses borescopes out there for $9.99 nowadays. This mechanic sounds like a chump, but I'm only hearing the story, what, thirdhand?
 
If your coworker gets real lucky, a timing belt might fix things.
If not, then the engine is screwed and it would be time either to junk the car or look for a replacement engine from a yard, on which the shop should of course do a timing belt replacement prior to installing it.
Whether an old Saturn would be worth this depends upon the car.
If it's trashed, then just trash it. If it's well cared for and pretty nice, then it might well be worth a used engine install.
Your post shows why timing belt engines must have the required service done.
Do this and you'll have no problems, while if you don't, you may.
This also poses a bit of a dilemma when buying a used car. Has the belt been changed as required or not?
A buyer often has no service documentation available, although a hunt through the glove box or spare tire well will sometimes yield a trove of receipts.
 
In those engines the ac compressor can lock up causing the serpentine to lock and can shear the timing belt. Basically the mechanic at this point has a blank check in his hand...it could be alot of things.

I am sure that after it happened the driver cranked and cranked to restart..if it did fail then the damage is done. Top end and possibly some pistons depending on the extent.
 
Ah yes, the same POS L81 engine that moved the Catera, a few Saabs, and the Vue before the Honda J series engines came into play

They're real fragile, especially with bending valves

Unless he adores the car, and has free labor, I think it's gmae over for this one
 
That car uses the awful Saab motor. Many of them did not even make it to 60k on the original timing parts.

As said unless they love the car to death just dump it now. It bends valves very easily so I doubt its ok.
 
There's a small chance it hasn't hurt anything.

If the mechanic won't attempt to inspect it with a bore scope I'd find a different mechanic. To require a whole TB job before ascertaining if any catastrophic damage has been done is not good troubleshooting - if it's gotta have valves, pistons, or more, the customer deserves to know that before consenting to spend any more than an initial diagnostic fee.
 
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Much quicker to just fit a belt and see if it runs...if it has bent valves you'll know then. Total waste of time to remove plugs and borescope each cyl. If it's a runner, then you can decide to do the whole job with seals, water pump etc.
 
While I don't think it's worth the money if it needs more repairs than a timing belt, the heads could come off, be machined, new valves, and it would probably be fine.

Rather than a junk yard motor that probably burns oil by the gallons and might knock.
 
Originally Posted By: krismoriah72
In those engines the ac compressor can lock up causing the serpentine to lock and can shear the timing belt. Basically the mechanic at this point has a blank check in his hand...it could be alot of things.

I am sure that after it happened the driver cranked and cranked to restart..if it did fail then the damage is done. Top end and possibly some pistons depending on the extent.



How does a locked up a/c compressor cause the timing belt to shear?. Unless the belt is driven by a timing belt driven accessory?.

Claud.
 
Broke a timing belt on a 94 Camry with 176K on it while going about 40 mph, had new belt installed and ran it for another 100K before finally trading it. It is not always an engine killer.
 
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