broken cam belt

[chiny15]

what can cause it and what damage can it do to my engine

I have a renalt espace 2.1 td, 158000 on clock, had cam belt change (amongst other things) at 141000 and whilst driving at aprox 40 mph it snapped
any ideas what could have caused it to go and what sort of damage could it have done
it is in the garage at the moment but they are being very vague about damage cause and most important repair costs
any advice would be greatly apreciated

Baz

 

[doctorwhen]

I recently had my cambelt changed, when I needed some other work doing - it's a major engine-lifty job on my car, so anything that reduces labour costs is good in my book!

Cambelts, like anything else suffer from wear. It's only a bit of posh rubber that spends it's time zipping round at 1000's of RPM, so it's bound to go eventually.

When it does, apparently, all of the valve timing goes to pot, and serious and expensive damage can occur as your pistons don't stop moving - only your valves do (assuming your car is moving, of course). The old "suck squeeze bang blow" (or diesel equiv.) process goes screwy and makes a proper mess.

A friend of mine had a cambelt go and he needed to replace his complete engine block. Luckily, he's a dab hand at this and can do it himself, so managed to get an replacement plant for a couple of hundred quid, and fitted it himself. He also said the engine "froze" and he had to coast his car to safety with the clutch in!

 

[chiny15]

thanks thats really cheered me up
will let you know the outcome

 

[david and julie]

Your cambelt as clearly failed prematurely, it could of been faulty,oil contaminated, badly fitted (something rubbing it)or something else may have seized(camshaft or tensioner) and caused it to break.

It is also not unusual for garages to use pattern parts which are cheaper, this amazes me considering the potential damage a failure can cause.

Unfortunatly you won't find out how bad it is until the unit as been stripped and inspected. The damage varies between one engine or another. It could be OK or even scrap.

Considering the mileage you may end up looking at a re-con or later low mileage engine from a salvage(not scrap yard)dealer.

Incidently is the garage that has your car now the one that fitted the belt?

 

[Porker]

Had this happen a couple of times on different cars. One a wreck so not bothered. Another that wasn't and the car was supposed to have full main dealer service history but the old belt was about half as wide as a new one!!

Some cars (Fords old Pinto engine) had no clash between the pistons and the valves so no damage usually but this is rare on modern engines now. The damage can range from a bent valve to a holed piston to completely smashed internals requiring a new engine. The causes as stated already are usually that the belt gives up (should not have happened in the mileage interval) or something this belt drives seizes maybe the tensioner or the water pump for example.

My only advice is that if the garage that fitted it takes some of the blame, make sure they replace everything that needs replacing (hard for you to tell) because shortcuts can be taken if they do the job on the cheap.

 

[chiny15]

yes it is the same garage that fitted the belt less than 16 months ago

 

[AdamW]

Pistons hit valves, valves get bent. Would be quite likely a new head would be required (as well as valves, obviously!)

Why don't they use timing chains now? I would have thought they would be more resilient.

 

[securespark]

Old Primera engine had timing chain - excellent!

Not sure if new engine has too..

Never heard of a chain snapping. Although if it has happened, no doubt I'll hear about it here....!

 

[chiny15]

just had repair bill for the car.£880 . not very nice is it.
why don't cars have a fly wheel like they used to do.Would be so much easier on the pocket.

 

[AdamW]

just had repair bill for the car.£880 . not very nice is it.
why don't cars have a fly wheel like they used to do.Would be so much easier on the pocket.

Ouch! Look on the vaguely less dim side: imagine getting that bill a week before Christmas!

Cars do still have flywheels. They are a bit lighter now (improved engineering means the engines are better balanced), which means you can rev more freely. But they are still there.

Formula One cars and supersports motorbikes don't have flywheels though. Which is why they can blip the revs up and down and redline at 19K or so.

But I reckon if your flywheel dropped off it could cause quite a bit of damage anyway: several pounds of iron rattling around inside the engine bay!

 

[horsechessnut]

At my garage they said to renew the tensioner and the water pump at the same time as they would be in a pretty worn state by then anyway and may prevent a jam and a mashed engine which could be too expensive to repair on some models.
Did you find out the cause of the damage or was the belt faulty do you think?

 

[noflame]

At 141000 if the tensioner and water pump have never been done then they most definately need doing!!
Its most likely not the belt's fault, but the tensioner seizing or just waving around causing the belts timing to slip.

Never heard of a chain snapping

Beemers are quite prone to it at this sort of milage!