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Greg
Greg, Technician
Category: Mercedes
Satisfied Customers: 7182
Experience:  Automotive diagnostic tech
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I own 2003 E200 Kompressor. In May 2010 timing chain broke

Customer Question

I own 2003 E200 Kompressor. In May 2010 timing chain broke and was repaired by a Mercedes main dealer. Mileage at time was 120,000Km. Last week timing chain slipped causing a lot of damage,again. Mileage 162,000 Km. How could this have happened?
Submitted: 4 years ago.
Category: Mercedes
Expert:  Greg replied 4 years ago.
Hi.

Sorry you been waiting for an answer, did see that a few experts did check out your question , they probably thought this question was something they never came across before or one of our MB experts have not seen this question ,

But i will help you with this as I've have come across this before with this engine .

This most likely happened when the timing chain was replayed and they did not replace the timing chain tensioner or the oil pressure was to low and the chain jumped teeth .

If you did hear chain chatter when starting first thing in the morning then could be due to oil pressure .

Have seen this happen to an engine due to oil sludge build up in the oil pick-up tube getting blocked up with oil sludge ,causing the oil pressure to drop hence a weak pressure in the chain tensioner causing the chain to be loose and jump teeth.

Worn sprockets which where not replaced on the first timing chain replacement .
Timing chain was not OE and a cheap chain was used and now has stretched
this can be checked .

Do you have the last bill with parts replaced .this would give you an idea what has happened .

If you need further assistance then please get back to me .

Kind regards Greg



Customer: replied 4 years ago.

Hi Thank you for that. However I need some more information. The bill for the previous occasion was:


Roller Chain


Expansion Plug


Protective Cap


Head Gasket


Exhaust Valve


Chain Tightener


The repair was carried out by a MB main dealer.


 


When they examined care on this occasion would they have seen if there was a build up of oil sludge?


 


The car was regularly serviced and any occasion when the warning notice to add a litre of oil came up on the display it was added.


 


Presumably on examination the garage should also be able to tell me if the chain stretched?


 


I don't quite understand your comments about MB experts


 


Thanks


Colm


 


 

Expert:  Greg replied 4 years ago.
Hi Colm .

MB (Mercedes Benz) .

The dealer should of changed the chain slide rails which i did not see on the list .

Chain streach the shop can check as there are limits to go by .

If they had the head off and replaced the cain then yes they would of seen oil sludge .

Rgds Greg
Customer: replied 4 years ago.

Hi Greg


 


What is the effect of not changing the chain slide rails?


 


You mentioned the possibility of worn sprockets not being replaced on the first occasion but how would one know if they were replaced or not?


 


I presume when they say the chain slipped that it jumped a tooth or teeth?


Would the chain and sprockets not need to be very worn to do this?


 


How unusual is it for the chain to slip after .only 42,000Km or 30,000 Miles done since the chain was first replaced.


 


Thanks


Colm

Expert:  Greg replied 4 years ago.
Hi Colm.

Its not easy for this chain to jump a tooth or teeth unless there is a lot of wear on the sprockets, chain slide rails , bad tensioner and stretched chain .
even with a stretched chain it will give the symptoms of a jumped chain .
if you don't have any bent valves then maybe you just have a stretched chain .

Regards Greg
Customer: replied 4 years ago.

Greg


 


There were 8 valves damaged


 


Can you comment on the chain slide rails?


 


Also on the worn sprockets issue?


 


Thanks


Colm

Expert:  Greg replied 4 years ago.
Hi Colm .

Worn sprockets will start to ware down after few hundred thousand miles .
so

Chain rails are a big possibility if this part brakes which they can, then the chain
could jump .


On the diagram the rail is part No. 7

Rgds Greg

Customer: replied 4 years ago.

Hi


 


I spoke with garage and they say there is no evidence of worn sprockets.


 


They also say there is no evidence of oil sludge


 


Excuse the questions but I'm not mechanically minded at all but are you saying the slide rails would have to have broken to cause the chain to slip?


 


If they didn't break, there is no evidence of oil sludge and no sign of worn sprockets does that just leave the tensioner as the cause?


 


Thanks


Colm

Expert:  Greg replied 4 years ago.
Hi Colm .

If this is the case then yes, just the tensioner could be at fault ,

So oil pressure will have to be checked .

These engine are well known for oil sludge and oil consumption due to sludge
as the piston oil rings stick and oil consumption gets high .

Greg
Customer: replied 4 years ago.

Hi


 


What test is done to check the oil pressure?


 


Colm


 

Expert:  Greg replied 4 years ago.
Hi Colm .

Oil pressure test is done at the oil pressure sensor port, with a mechanical pressure gauge with a running engine .

Greg
Customer: replied 4 years ago.

Hi


 


Ok but presumably they cannot do this test until car is repaired?


 


What's a good or bad result?


 


Colm

Expert:  Greg replied 4 years ago.
Colm the shop will know what pressure is needed at idle and at 3.000rpm .

Example for your engine, you should have at idle 800rpm 0.7bar
and at 3.3000rpm 3.0bar..

Greg