HELP! I am a single woman and I need some good advice. My 1991 300CE with only 38K miles is in trouble. My engine was making a little bit of a rattle noise so I took my car to the Mercedes Dealership. The Mercedes Dealership tells me that I may need a new timing chain and rails. They will check it out by taking the valve cover off at a cost of $230. (this is just to check it) The dealership replaced the tensioner and feel that a visual inspection of the chain is a good idea. They are concerned about the rails due to the tensioner problem that they fixed. If the chain need to be replaced they say that it takes 7 hours of labor. Total cost including chain and rails of around $1,400. Does this sound like the right thing to do? Does the cost seem correct? Any help would be greatly appreciated.

What octane are you using. I sometimes get this with 89 octane but never with 91 octane. Timing chains usually last 100-150k miles. I have 250k miles on mine, still w/ original chain. If they tell you it needs to be done, tell them to change the head gasket while they are in there so you won't have any oil leaks.

I think the dealer is just trying to take your money.

Based on all the experience of the techs that post on this site, none of them ever recommends timing chain replacement on a six-cylinder engine like yours. The reason is that the chains do no stretch or become loose. The chains are very short, and don't change direction (like the chain on a V8 engine).

Further, these M103 and M104 (yours is an M104) engines have a ratcheting tensioner, which is another reason for timing chain durability. It uses oil pressure as do others, but as the chain loosens the plunger "ratchets" to keep the chain tight, even after the engine is shut down. Since there is no looseness during that cold start up, it does not hang up on "stuff" causing things to break, like timing chain guide rails.

The V8's use plast guide rails (which break as they become old), but I believe your engine uses metal guide rails.

Anyways, the dealership replaced your tensioner, and this should be keeping your chain tight.

If you still hear a noise, your chain is not the problem.

I would not take your car back to the dealer, but rather take it to an independent garage that specializes in Mercedes Benz vehicles.

My $ .02,

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I bet the noise is made by the little belt tensioner shock (or bushings) in front of the engine. It is NOT an uncommon problem. Open the hood and try to locate the noise. BECAREFUL! Do a search!
Good luck!

__________________
J.H.
'86 300E

J. Hidalgo is right.

That serpentine belt tensioner can make a racket if it's going bad.

There is also an idler arm pulley that this serpentine belt goes around as it loops around the water pump. The bearing in this pulley can also make a rattle noise.

Last, your water pump could also make a noise if it's going bad, but you would also be likely to see a coolant leak or be losing coolant.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Sounds like the dealer is pulling your leg. Like a previous poster said - check the belt tensioner. What part of the country do you live in? You need to try to find a good independent MB shop in your area.

__________________
Jim

I want to thank everyone for the information.

I live in the Tacoma Washington area. If anyone knows of a good reliable independent, please let me know.

Can anyone tell me for sure if the rails are metal in this car? I would think that if they are, the potential of a problem with them would be very limited. Am I correct to assume this?

Again, thank you.

They may be "metal backed" guides. You really should not be having chain/guide issues at that low a mileage. Do a search on this site for independent shops. I'll bet there are a couple/few goods ones in your area. I'm kinda surprised you needed a new chain tensioner at that low a mileage. Again, it is probably just the belt tensioner shock.

__________________
Jim

This thread lists three good shops in Tacoma:

http://www.peachparts.com/shopforum/showthread.php?threadid=3568&highlight=tacoma

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".