Cam chain problem

[Redcamel]

Hi all, I'm having an issue with my new 1980 300sd. Checked the timing and lined the timing marks behind the cam chain sprocket up. Looked at the gauge by the crank and it reads 17 degrees to the left of zero. The chain has no lift off the sprocket, tight. Any ideas? Thanks in advance.

[rreeuuvveenn]

If the car car drives well,

The Timing dial pointer might be off, loose bolt maybe?

[Redcamel]

I'm going to check that right now, thank you

[Redcamel]

Not to say it wasn't moved in the past but its tight now.
Could the harmonic balancer have slipped a lot at some point or a little here and there causing this?

[Maxbumpo]

Originally Posted by Redcamel

Not to say it wasn't moved in the past but its tight now.
Could the harmonic balancer have slipped a lot at some point or a little here and there causing this?

Not likely.

[Redcamel]

The engine sounds good and it drives good too. A little smoky but I just changed out 3 broken valve seals and I adjusted the valves but other than that the engine runs good.

[rreeuuvveenn]

I Do not know,

[Redcamel]

Ok I appreciate your time thank you

[barry12345]

I would find and verify top dead center. It is doable with a liquid in the first cylinder. Then see what you have.

[Maxbumpo]

Originally Posted by barry12345

I would find and verify top dead center. It is doable with a liquid in the first cylinder. Then see what you have.

X2, this is the proper next step to verify Top Dead Center (TDC) so that you can either validate the pointer or calibrate the pointer.

If you really have 17 degrees of stretch, your timing chain is in dire need of replacement! If it fails, the engine is for all practical purposes destroyed. MB sells off-set woodruff keys to correct the valve timing up to 9 degrees of stretch. Presumably one can safely use a chain with up to 9 degrees of stretch, my personal rule is that 5 degrees is the upper limit.

[Clemson88]

When was the chain last replaced?

[Mike D]

17 degrees is pretty close to being a full tooth off if I remember correctly.

[rreeuuvveenn]

Is it the first time you are checking the timing of your "new 300SD" ?????????

[Redcamel]

When was the chain last replaced?

I'm not sure, I bought the car about a month ago. I asked the PO if he knew when it was replaced and he replied that he didnt have it done in the last 20,000miles that he had it.

[Redcamel]

Is it the first time you are checking the timing of your "new 300SD" ?????????


Sure is, ive checked it about 20 times since I've had the valve cover off. Spent the last 2 weeks trying to figure out why it's off so much. I was told that I should figure out why the timing is off before I change the chain because just changing the chain may not fix the underlying issue.