Timing-chain breakout!!

[45232]

Hi there - Has anyone ever had the timing chain on a SL500 '96 slash it's way out thro' the cover ?

 

[television]

Hi there - Has anyone ever had the timing chain on a SL500 '96 slash it's way out thro' the cover ?

That does not happen these days, and certainly not on that engine, the tensioner would have to be non existent for that to happen.

Malcolm

 

[45232]

How could that be? The car was going fine up to that point!
Is a tensioner one of the 'matchbox ' size plastic things? They found one in the sump all curned up!

 

[television]

http://www.detali.ru/cat/oem_mb2.as...GA=722.353&CT=M&cat=518&SID=05&SGR=015&SGN=01

Was the car noisy before it went, the set up is in the picture above.

Malcolm

 

[Ultymate]

Perhaps if it was'nt noisy beforehand there could have been either a siezure or failure of another component which caused the failure of the chain, I'm thinking particularly of your camshafts and or their sprockets :???:

 

[television]

Perhaps if it was'nt noisy beforehand there could have been either a siezure or failure of another component which caused the failure of the chain, I'm thinking particularly of your camshafts and or their sprockets :???:

It takes a fair time to wear right through the cover,and it can only do that on the tensioner side,thats the puzzle

malcolm

 

[type49]

Guide pin come out? Can't really picture them on a 119 - never pull them apart, they're generally bullet-proof.

 

[Ultymate]

Did the chain wear it's way out of the cover or grenade it's way out ?

 

[Hibbo]

Photos please!

I know nothing about this engine, but I would've thought that for the chain to be loose enough to do this the engine would have self-destructed or at least stop running long before this could happen.

 

[eric242340]

Timing chain breakout

The 119 engine is one of the strongest that benz ever built. This sort of thing only happens as the result of poor repair work. There is a known issue with the tensioner, however it can only happen if the tensioner was fitted incorrectly. So the first questions are;
a. What is the service history of the car.
b. Have there been any major repairs done recently
c. Was there enough oil
d. Did the engine overheat just before the loss of power
e. Was there further damage ie pistons valves ect
Im sure we would all be interested in your reply. I hope we can find an answer to this one.

 

[45232]

Hi Eric
I had bought the car 2 months before this happen from a friend who had had it for nearly a year! There is service history which I shall have to look into.
As soon as I bought the car I took it to a main Merceded Dealer in Cambridge for a Lub Service, they never mentioned about anything else wrong with it that would have caused this! (Unless of course they didn't put enough oil in it?
I drove the car a lot before this happened - and iy was fine. The this particular day I'd gone 25 miles with no trouble, parked up to shop, got in the car again - started to drive home and about 10 ins into the journey noticed a lack of power and the oil light came on. Not knowing what was wrong I carried on the rest of the way home, and when nearly home noticed a lot of smoke coming from the car (I suspect it was the oil pouring from the slashed camshafr cover burning 1) whe I got home and lifted the bonnet there was the jagged slash in the camshaft cover about 8 inches long! You counld see the timing-chain through the slash! The engine was never started again, but pushed on a low-loaded and taken to the garage, who stripped it down and found the mangled tensioner, but could offer no reason why it had happened. I consider myself lucky the engine wasn't ruined! AND how did I manage to drive it the last 10mins home with no chain working OR could it drive on one side only of the V* engine?
You are all only confirming the idea I have had from many other people - that this could not possibly happen!!!!!!!!!!!!!!!!!

 

[ben12345]

Was it the oil pressure light, or oil level light?

It doesn't sound good!

 

[television]

Hi Eric
I had bought the car 2 months before this happen from a friend who had had it for nearly a year! There is service history which I shall have to look into.
As soon as I bought the car I took it to a main Merceded Dealer in Cambridge for a Lub Service, they never mentioned about anything else wrong with it that would have caused this! (Unless of course they didn't put enough oil in it?
I drove the car a lot before this happened - and iy was fine. The this particular day I'd gone 25 miles with no trouble, parked up to shop, got in the car again - started to drive home and about 10 ins into the journey noticed a lack of power and the oil light came on. Not knowing what was wrong I carried on the rest of the way home, and when nearly home noticed a lot of smoke coming from the car (I suspect it was the oil pouring from the slashed camshafr cover burning 1) whe I got home and lifted the bonnet there was the jagged slash in the camshaft cover about 8 inches long! You counld see the timing-chain through the slash! The engine was never started again, but pushed on a low-loaded and taken to the garage, who stripped it down and found the mangled tensioner, but could offer no reason why it had happened. I consider myself lucky the engine wasn't ruined! AND how did I manage to drive it the last 10mins home with no chain working OR could it drive on one side only of the V* engine?
You are all only confirming the idea I have had from many other people - that this could not possibly happen!!!!!!!!!!!!!!!!!

The pin holding the bottom of the tensioner guide rail must have sheared or come out, this wold have allowed the tensioner its self to come into cantact with the chain.

The chain would have quickly destoyed the tensioner, at that point the oil pressure was lost.

The engine would still run perfectly and the timing would be intact, as this is all done on the other side of the engine, where the chain is tight.

There tensioner guide rail could have then pushed the slack in the chain up against the timming case cover, and it would not take long to come through.

Malcolm

 

[television]

Was it the oil pressure light, or oil level light?

It doesn't sound good!

Hi Ben, it would have first the pressure lamp, and if the engine could have run long enough without oil pressure, the level lamp would have lit, if fitted.

The oil pressure is the important one, In this case there would have been a little pressure for the main bearings and big end journals.

malcolm

 

[eric242340]

Timing chain breakout

Hi Ben, it would have first the pressure lamp, and if the engine could have run long enough without oil pressure, the level lamp would have lit, if fitted.

The oil pressure is the important one, In this case there would have been a little pressure for the main bearings and big end journals.

malcolm

Hi Malcolm, this is a 119 engine and the instrument cluster should have an oil pressure guage and the warning lamp would be for the oil level. But it seems to me that, for some reason, there was not enough oil. Either they dident put enough in (which I doubt) or an oil leak somewhere. But looking at the age of the car it is possible for a chain guide pin to break, this would sadly be just an unlucky event. In all my years in this trade ive not come accross this one. And the 119 engine was one of the best built, beats the new one all hands down.

 

[television]

Right now we have 5 timming chain threads on the go, did not get one last year, life is odd.

Was going to say on this thread, do not put the old timming chain back, it could have been twisting badly. For what they cost I would not trust it.

Malcolm

 

[45232]

The chain slashed its way out - broke out the side of the cover all in one go! and the oil camre out thro' the slashed case!

 

[45232]

Malcolm
I tend to think you have the nearest answer to this....but why would this happen? Why does everyone say this shouldn't happen?

 

[television]

I think the same as type 49 that the pin came out or sheared of .
this engine is not the same as your,but will do for this, Ihave put an arrow on the left showing the pin, that is the fulcrum point for the tensioner guide rail.

Once that cam off the chain is free to destroy the tensioner (4) on the left, allowing the chain to come through the cover, you can see the cam wheel over the tensioner,once the tensioner has gone, the chain is flapping free.

As said though almost an unknown fault

Malcolm

 

[jberks]

about 10 ins into the journey noticed a lack of power and the oil light came on. Not knowing what was wrong I carried on the rest of the way home, and when nearly home noticed a lot of smoke coming from the car

You say you continued to drive with a loss of power and the oil warning light on? 2 signs of trouble that would have even my Mum pulling over and switching off as quickly as she could, certainly not driving home.
How a chain tensioner would cope without lubrication I don't know, but its total destruction wouldn't surpirse me and after that, all bets are off. I suspect the chain was a symptom rather than the cause and if your engine survived all this without other major damage I'll be very impressed.