Renault Laguna timing belt snapped!!

This is a valve muncher. Damage most likely. Did you try and crank it when the engine packed in or did you know what happened straight away?

It will hurt anyway. You're probably talking about a rebuilt head at the least, providing a valve hasn't punched a hole through a piston. Really depends on damage caused.

Ta, G.

500 pounds minimum up to 3000 max

The car just died on me while driving. I had a look under the bonnet and could see what I thought was the timing belt so had a go at trying to start it!!! It obviously wasn't the timing belt I could see! My dad had an old MK3 Escort and when his timing belt went you could literally hear the metal colliding with each other. On the Laguna I couldn't hear a thing. I just thought it had cut out.

S.

That good eh? :o( The most annoying thing about it is we traded my wife's car in a couple of months ago because we thought it would cost a fair bit in the coming months!!!

S.

The thing is: it is extremely rare that a timing belt fails if it has been changed properly at the recommended maximum intervals. If this is a car you recently bought, then unless you personally knew the service history, a new belt and an oil change would be the minimum you should have had done within days of getting it. I know it is easier to be wise afterwards, but even the local paper recommends belt changes on newly acquired cars. It may well be uneconomic to repair your Renault, so keep an eye out for something else.

mrcheerful

The message from "G-Man" contains these words:

Valves from Renault come in packs of four. Even if you've only bent one inlet and one exhaust they'll still sell you two packs of four which will be over £250.

Heh, years ago I got called out to a MK3 escort which had "just cut out"

I couldn't turn the camshaft with a spanner :-))

Steve

New website........

:-)

Damage will be to valves and you will probably need a new cam spocket as the "woodruff key" is incorporated in the cast and shears when the first valve hits a piston.

Had it happen, would you believe twice in a fortnight. First time was caused by chaffed serpentine belt seperating and getting under cambelt. this was caused by the alternator pulley which was changed on a 'red recall' after the cambelt incident!

Second was a plastic type water pump pulley which cracked and let go. This has now been updated to an alloy type!

Sold car very quickly at a lost. Probably run for years now.

A multi million-pound worldwide industry built up on the back of snapping rubber bands. If the manual says change cambelt at 70,000 miles, but they keep breaking at around 40,000 then our major modification will be that we'll alter the manual to say "Cambelt must be an replaced at a maximum of

36,000 miles"... Does this sort of calamity happen with Rollers, or do they incorporate some sort of fail-safe or warning device?

I'm sure pattern ones would be available though. Mike.

[...]

What a stupid non-fail-safe design a timing belt is. My Saab 9000 has a timing chain - of course.

My wife's old Punto timing belt snapped a few months ago. I was dreading the outcome. But apparently no damage is caused when this happens. Not having a clue about engines, why do some cause so much damage yet others get off scot free?

Combustion chambers are often shaped to reduce the surface/volume ratio. That may be a bowl in the piston or a hemisphere above piston. If the valves don't clear the piston in every position, then you have a problem.

i guess its up to the ethics of the engineering team designing the engine .

assuming that timing chains are no longer in fashion: a)they can decide to make an interference engine where valves/pistons will collide if the belt snaps.this will give them more freedom in shaping the chamber for (marginally??) better fuel combustion->more power and fuel economy

b)or they can decide to make a non interference engine where the piston has depressions in it so that a valve will never impact on it. this engine will be more forgiving on people who race/neglect/ forget/cant afford/ dont know they need to change the belt.

now since

-a timing belt will last the warranty period (at least for normal use of car)

-that the longer the average car lasts the less cars will be sold in the future

-manufacturers are less interested in consumers who cant afford to change the belt at recommended intervals

which way do you think the engineering team will go? i wonder why anyone goes for b) today. (i think it might have to do with submitting cars for rally competitions where you dont want to retire a car just for a belt snap.)

The message from "Mike G" contains these words:

Certainly, but only if he goes to a proper garage instead of a Renault dealer.

The message from Johannes contains these words:

Chains aren't inherantly fail-safe - they just don't fail very often.

At least when a belt snaps there is a pretty good chance that it fails loose and the valve springs will push the cam to a neutral position pretty quickly, with a chain it'll stay in contact with the sprocket for longer and probably generate more damage by forcing the cam around and the valves into the pistons.

Chris

But the timing chain will rattle long before it fails. Direct failures are unheard of. The chain will last far longer; there is no set mileage for changing a timing chain. It can easily last to 200,000 miles. However, changing the timing chain is an expensive operation, bill around £1100.