Continuing the mechanical work on my newly acquired 85 300sd.
I checked cam timing with the cam tower alignment mark. It was out by around 8 deg – this definitely effects the engine operation.
I’m inclined the use an offset woodruff key and correct the timing (cam and injection pump), but I recognize that is close to the high end of what MB foreseen to correct with offset woodruff key. Replacing the chain can spiral out of control, replacing other parts, sprockets – all three?, tensioner, guides? So I would like to address the issue, but not throw parts at it unnecessary.

The timing chain sits tight in the sprocket - I can lift it maybe a 1mm.

Otherwise the engine runs good, started in cold w/o any issue. I just had one tank measured mpg that was around 20 – low, could explain the timing being off
I did a compression check 3 – 380psi, 1-360psi and 1-350psi. Not bad, especially knowing the cam timing being off.

Pulled injectors – sprayed good, pops at right pressure but leaks down way to quick, so planning to rebuild them.

At this point I'm only worried about the timing chain. Do I need to replace the timing chain or just use offset woodruff key.
Is there anything else I need to check around the timing chains before make a decision?
Thanks
Zoltan

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I'd suggest replacing the chain and using a crimp tool. Replace the accessible chain guides and tensioner. That chain is not overly difficult to replace. After running the new chain for a couple hundred miles dial in the pump timing.

Your compression #'s are rather good.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Using an offset woodruff key on the cam gear will only give you five degrees. The chain stretch isn't going to get any better. You would be 50 percent the way there of replacing the timing chain anyway.

I'm a lazy guy. I don't like to do things twice. Using an offset key will give you some time but as I said, the stretch isn't going to get better.

I'd either run it as is until it gets worse or replace the chain.

As an old boss of mine always said, "If you don't have the time to do it right the first time, when are you going to have the time?".

Your car, your time and your money.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

thanks for your input.

If I use the offset woodruff key I can correct the 8 deg, per FSM there are 4 offset keys, 4, 6-1/,8 and 10 degree on the crankshaft.
I assumed if I used 8 deg it will correct the 8deg off timing on the crankshaft. Am I missing something?

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If you are only looking at the timing marks, you don't know enough to make a decision. Use the 2mm lift method to get a more accurate assessment of chain stretch. The cam marks have told you enough you need to look further, but you need to use a dial indicator to actually measure the stretch. You could be off by 3 or more degrees just using the cam mark.

__________________
1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

Shadetree is right. I meant to mention the correct way of checking timing but got sidetracked.

The offset changes you mention are for installing the key on the CRANKSHAFT. Installing the crankshaft key is a heck of a lot more involved than the cam.

Cam rotates at half the speed of the crank so divide the correction in half.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

agreed - I think I have lined up the marks on the cam well, but I have planned to do the 2mm intake lift timing for the weekend. I'll see if it changes the question.

that's not how I understood - I thought those are cam woodruff keys and offset timing is referenced to the crank. If you are right and it is for the crank sprocket, than it is pretty big job pulling that off, make it absolutely not worth the effort.

We may have a communication hiccup??? or I'm wrong but I believe the offset key is installed at the camshaft. Others are saying the measurement in degrees is viewed at the crankshaft as 8° which equals 4° at the camshaft.

Is it possible there is an offset key in there already and it is stretched even more or a key in backwards? Hmm...

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

I cannot tell who is right, but I assumed that the offset key is for the cam, and once installed it corrects said amount relative to crank position. This how I understood the FSM, and it made sense to me since the cam timing check is also measured relative the crank pointer.

can it be an offset key installed, and chain further starched - yes. if this is the case the chain needs to be replaced. No questions or ifs and buts.
can it be an offset key installed backwards - sure. I'm have been amazed before.
what I do know, is that I have not find any related work in service history, but there is some gap in it.

The camshaft gear is indeed installed on the cam drive gear. The chart he referenced is for timing change at the crank.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Just run in a new chain. I've done two of them, once they got to 5 degrees. Not worth the risk of a destroyed engine if that chain breaks.


Both times, I simply used a ball peen hammer and a 10lb sledge hammer (as the 'anvil') to peen the end of the pin. Works fine, and if you are patient and do it right, you actually get a much bigger 'mushroom' on the end of the pin that what the crimping tool makes, so you never need worry about that link coming apart.


Also, I would not worry about replacing the rails unless they are really deeply groved. I did have to do that on one OM603, not a fun job as all the stuff has to come off of the front of the engine including the crank damper.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

thanks for your input.
I have definitely considered this route, but i'm kind of leery crimping it without the proper tool.
I have not done this before, if I do it I want to do right and use a crimper.
On the other hand I have read the FSM, and there was the option to correct the timing. I thought if MB offers this as a solution the chain replacement is not outright necessity. I don't have the experience hence this post.

That assumption is correct. (I can tell who is right.)

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I go with post #2. I pulled out the large timing chain tensioner rail on mine and found part of it was coming off. It has less than 300K on it.

I have not read of anyone changing the sprockets unless there was obvious damage to them

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84 300D, 82 Volvo 244Gl Diesel