Timing belt symptoms?
 

what happens when a timing belt breaks? does it cause a total shutdown of the car or are there problems before the break? thanks.

Mercedes doesn't have a timing belt, they use a chain. You may be referring to the serpentine belt that drives the accessories like the Alternator, Water Pump etc.

Steve

If you are refering to the serpentine belt, the first sign of its failure would be the 'no charge' light would instantly illuminate due to the alternater losing its drive, at the same time the steering would lose its 'power assistance' and become very heavy, if you continued to drive the car, the engine temperature would increase due to the water pump not being driven and excessive engine temperature would eventually cause damage to the engine.

Nothing, Mercedes doesn't use them.

I think when the timing chain/belt breaks on any car.... it is a very violent and horrible process..... I don't know about any symptoms or sounds you might hear before...

It is not a "violent and horrible process" on ANY car. Some engines are such that if it breaks the valves will not contact the pistons, thus do no harm except leave you beside the road. Once the belt is properly replaced the engine will be on its way again. This is called a non-interference engine.

Most engines nowdays, and all MB engines to my knowledge, are interference engines, meaning that if the valves are not properly timed they will contact the piston tops.

The irony of the whole thing is that among the timing BELT equipped engines, the non interference engines are usually the ones that provide a very quick and simple replacement of the belt. Go figure.

Have a great day,

It's a violent and horrible process if the engine is an interference type.

Pretty horrible when you are handed the repair bill.

I stand corrected!

Regarding the failure of a timing belt/chain.
When a valve travelling downwards at nano speed is involved in a head on with a piston travelling upwards at nano speed i would consider Rahulio's description of the event as "a violent and horrible process" as pretty accurate.

I serve the VW market and sell quite a few timing belt kits to VW drivers. I also worked on VW's for ten years prior to opening my parts biz. Every tbelt failure I've ever heard about is as undramatic as you could imagine. When the belt breaks the car quietly dies and won't restart. The sound of pistons hitting the open valves is covered up by engine noise and the bent valves are visibly hardly bent. Hardly is enough though...

Jim

Yes I, too, would say it's mechanically violent and nasty but you don't really notice it or hear anything.

However, I believe afterwards you will find the engine has no compression, so if you try to start it, it will turn over not with the usual cha-cha-cha-cha-cha-cha but instead a very different constant whine, like a motor spinning freely (which it is!)

good luck

Russ

dieselgeek,
I agree,...the actual event is fairly undramatic as far as driver awareness is concerned.....my reference to Rahulio's 'violent and horrible' comment is in regard to the actual process inside of the engine which, at its extreme, can result in, bent valves, damaged pistons, broken camshaft/rockers, bent con-rods, damage to cyl-head, etc....fortunately, the damage,in my experience, is usually limited to bent valves only.

Okay guys, I'll try this ONE MORE TIME!

There are INTERFERENCE engines, and there are NON INTERFERENCE engines. In a non interference engine, the valves NEVER strike the pistons, EVEN if the timing belt/chain fails! Thus in a non interference engine it is NOT violent and horrible.

In an inteference engine, the results IS INDEED violent and horrible. In a non interference, loss of the timing/chain belt does no damage to the engine other than having to replace the obviously broken belt/chain.

Do you understand now?

Have a great day,

larryBible,
Calm down.......i believe the earlier point you made about interference and non-interference engines has been taken on board, i also believe you missed the point that further discussion has since moved on and is about the consequences of chain/belt failure on INTERFERENCE engines.

Hey, Larry is trying to make sure all understand what he said. I take exception to criticizing his offering in this instance. If you want to get picky, when a timing chain (or belt, for that matter) fails in an interference engine, the valves do NOT travel down at a high rate of speed and contact the pistons which are travelling upward. The valves become stationary, some in the open position, and the pistons contact them on their upward stroke. The results are usually a broken camshaft, possible holed pistons and maybe a bent rod or two. (and I'm speaking from experience here.....)

Cheers,
Wes

p.s. Larry, illigitimy non-carborundum :D