I was reading the procedure for replacing the timing chain. I have a clacking noise that i was told was the timing chain. I am going to check the chain stretch, but the noise sound very much like a lifter noise to me. It does come and go.

In case I need to do this, something is confusing me. It says to remove the chain tensioner as one of the first steps. Then after that, with the chain retainer holding the chain to the cam sprocket, you break apart the chain, link the new one to it temporarily and then crank the crankshaft while pulling the new chain through.

My question is, why do this with the tensioner out? It seems that the chain has the potential to skip a few teeth as the crank is being turned unless the belt is being pushed in. I realize that the belt is apart at this point so maybe it doesn't matter, but I'm worried about loosing chain position even with the retainer in place because it may slip off of the bottom sprockets.

Also, can ALL of the chain guides be replaced without removing the head? I saw that the one that the chain tensioner pushes against needs head removal?

I'd like to replace all of them as long as I don't have to pull the head or the oil pan.

Thanks

We need some more information. Car model, mileage, etc. Also what kind of oil are you using? When I first got my car I had lifter tap almost always. After I switched to Mobil 1 5w40 Turbo Diesel Truck Oil, it has all but disappeared. WELL WORTH IT!

It may also save you from doing a timing chain job, which if lifters are the problem then if will not do a thing. Do not get into a project bigger than you need to, usually chain stretch is not an issue until 3-400k from what I hear, and even then it is minor.

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

I would think the engine is what is the pertinent item here, but it is a 1991 350SD. I am using Chevron Delo 400 LE

True, and what is the Mileage?

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Just a few miles shy of 200,000.

Something is confusing me as well.

You have a "clacking noise". This is factual.

You were "told" that the noise was the timing chain. Who told you this? How much experience did this individual have with this specific engine. Did he ever replace a timing chain before for the same symptom?

You believe the noise is a lifter. You may be perfectly correct. This engine commonly suffers from lifter ticking that does come and go.

And yet, you proceed down the path of timing chain replacement, which is fraught with risk for a person who has never done it without the slightest hint of data to confirm that this is your problem.

The person that told me it was a timing chain was my indy with 20+ years of Mercedes experience. He has lost count of how many timing chains he has done. He said that is where the noise was coming from per a stethescope.

I have not checked chain stretch (and don't think he did either).

Less confused now?

Do an oil change with the Synthetic oil I mentioned and see where it is goes from there. It is a highly recommended oil for the 603 anyhow so no harm done either way. If it does not work than all you have done is changed your oil. I ran the same Delo oil and had ticking, switch to Mobil 1, ticking disappeared. I have 210k on my 603 which has been on the Mobil 1 since 160k and my timing chain is fine.

We are just trying to avoid you changing a part that is difficult and has some risks, when in the end, it is most likely not your issue. The reason why my lifters are clacking is probably because they are worn so maybe you are in more need of lifters than a chain, however said oil change may resolve that as well :-)

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

yes, I've actually considered the Mobil 1 and even an oil flushing chemical like from BG products. I agree that this can't hurt.

I believe my mechanic that the noise was coming from the chain area so I still need to check chain stretch. With 200k on the motor and not knowing when or even if it has ever had a chain changed out, I don't want to have a catatrophic failure because I ignored his advice either.

I am just trying to gather information on the process in case I decide to move forward after seeing if I have any stretch. I am still hoping to get some information on the initial questions so I understand it better.

by the way, with 210k on yours - do you have any idea if you are still on your original chain? I know you are supposed to chainge them way before 200k

Mine has never had a timing chain swap and I do not believe the om60X series requires it at a certain interval. I have never even heard of timing chain failure on a 603.

http://www.benzworld.org/forums/w124-e-ce-d-td-class/1611100-om603-timing-chain-stretch.html

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

The reason the Timing Chain Tensioner needs to be removed is that with slack in the Chain after it is cut the Spring is going to push the tensioner too far (and the new Chain with it) and when you go to put the Master Link in you the Timing Chain is going to appear to be too short; you are not going to be able to connect the Master Link.

If the newer Engines have a Timing Chain Tensioner with a ratcheting device in them you will not be able to compress the Tensioner Piston without a whole lot of force and maybe damage.

With the Timing Chain loose and the Timing Chain Tensioner installed is it possible for the Timing Chain Piston to pop out if it is left installed (I am assuming you would be changing the Timing Chain Rail also)?

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84 300D, 82 Volvo 244Gl Diesel

Thanks, that's good. First step since I have noise coming from there appears to be to check the stretch. I don't think the oil was necessarily replaced at proper intervals on this car. There was an enormous amount of sludge in the intake on this car -- much more than my other two.

There may or may not be wear on the chain guides because of this, but I'm not inclined to change them unless I change the chain.

The linked post also recommended the Delo 400 LE and Shell Rotella T, but I have heard lots of stories about the use of synthetics to curb noises.

If the chain is not stretched, I may replace the tensioner which may be the cause of any noise. After all, if I have noise coming from there, and the chain is ok, the only things left are the tensioner and the guides.

I saw that the guide associated with the tensioner requires head removal. Does that sound right? It sure doesn't seem like it would be necessary based on it's location.

Chain stretch is really chain wear between each of the links, cause by lack of lubrication, avoided by lubrication. Synthetic oil is much better at lubricating, especially when loaded with soot and when it has been overheated. I think changing the chain tensioner is a good start, I have meant to do that on mine in fact!

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Thanks for the info. That all makes sense. Brings up another question though. The Mercedes chain retainer looks as though it keeps the chain engaged to the cam sprocket, so the length of the chain should be ok when it comes back around to connect the new link -- or can it still appear to be short because of the tension even if it has engaged all the teeth upon rotation?

Also, the slack from removing the tensioner won't risk the chain falling from the crank sprocket? I could see the slack from the chain causing the chain to droop on the bottom even if the top of the chain is engaged on the upper sprocket.

Probably dissecting this too much, but I want to make sure I have a mental picture of this.

The manual talks about removing the head to change the timing chain rail associated with the tensioner. I don't understand that. At the same time, it seems the timing chain cover would be a problem in terms of getting the pin put back in the hole of the new rail since visibility is limited to the little hole itself.

Am I on track?

You won't be able to remove the chain tensioner rail without removing the front cover.

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Jim