Timing Chain replacement for a 1994 SL - PeachParts Mercedes-Benz Forum

rgrayoh · #1 12-09-2007, 08:04 AM

I took my 1994 SL500 into the dealership to check out my "Engine Check Light" which was on and they went through my car. As it ended up being they said that it is the " Transmission Upshift Delay Valve" that needs to be replaced. While inspecting the car they said that I need a new timing chain that is recommended to be replaced by Mercedes Benz at 100,000 miles. I currently have approximately 123,000 miles on the car. Can anyone tell me if this is true or are they trying to sell me on a $1,000 repair bill.

deanyel · #2 12-09-2007, 11:42 AM

Not true that MB says replace at 100k miles. Any other evidence of a problem? It is a good idea to take off the valve covers and look it over and at least replace the upper guides, and perhaps the tensioner.

rgrayoh · #3 12-10-2007, 12:40 PM

That is good to hear. Looks like my dealership was just trying to sell me a bill of goods at a $5,000 cost to me.

ctaylor738 · #4 12-10-2007, 05:13 PM

This picqued my curiosity, so I looked it up on AllData. Would you believe that the maximum stretch allowed is only 2 degrees? I would be amazed if a chain that long wouldn't stretch that much in 123K. So maybe the dealer isn't just hustling work.

It's 7.9 hours, plus $225 or so for the chain.

rgrayoh · #5 12-20-2007, 08:21 AM

To: ctaylor738

or others:
Super Moderator

How can I tell if my timing chain has stretched more than 2 degrees as you mentioned in your answer?

ctaylor738 · #6 12-20-2007, 09:35 AM

It's a rather involved procedure. You would need to remove the right cam cover, turn the engine to a specified position, and use a dial gauge to measure the lift on (I think) the #1 exhaust valve. It is probably more work to check it than to simply replace the chain. I don't think that there is an offset key to correct valve timing if the chain has stretched.

The bottom line is that the chains do stretch and the guides wear, get brittle, and sometimes break. The tensioners lose their seal and start to leak down. This is a fact of life with the M116 and 117 V8's, and there's nothing hugely different about the design of your engine.

Obviously, the advice you got from the dealer was motivated by the desire to make some money. But that doesn't necessarily mean it was bad advice. If you are going to keep the car for a while and want it to be in primo condition, it's something to consider.

Personally, if I was looking at this car, I would be inclined to pay a premium if the chain was replaced. But your average used 129 buyer could probably care less.

deanyel · #7 12-20-2007, 06:11 PM

Well maintained 119 motor chains are bulletproof. Well maintained means the upper guides and tensioner have been replaced. My sense is that most cars are driving around on their originals.

ctaylor738 · #8 12-20-2007, 07:55 PM

They are probably bulletproof in that they are a double-row chain, and don't break. But that doesn't mean that they won't stretch. IMO it would be penny-wise and pound-foolish to replace the rails/tensioner and not do the chain (available for $140 and change).

It will be interesting to see what happens as more of the cars with the M119 start hitting the 120K mark.

deanyel · #9 12-21-2007, 10:21 AM

But the cost of the chain is a small percentage of the cost of the job. Plus replacing a good factory timing chain has its own risks. I know a mechanic who had seen a lot of 200k mile 119s without a problem, but is now seeing lower miles cars with broken upper guides. The theory goes that the issue is not really miles on the chain but age on the plastic guides.

ctaylor738 · #10 12-22-2007, 10:14 AM

Looks like I'm in the minority, maybe even by myself on this one. I queried two of the major online suppliers with the question "Do you sell a lot of 119 chains?"

And the answers were, "No" and, "Hardly any."

Now I feel bad for all those 119's out there not living up to their full potential because of their stretched chains. :-)