When do the valves meet the pistons?
 

Doe anyone know how far before and after TDC the camshaft timing can go?

18° at the crankshaft is the generally accepted limit (one tooth).

I will just throw this in. I own an 81 SD. When I bought it 10 years ago I knew a lot less about MD diesels than I know now. (A common occurance I am told)
The engine ran like crap. After reading and running tests, I took it to a well know MB tech. He noted the engine idled rough and would not smooth out when revved up. Had a lot of strange noises going on,even for an old diesel. His conclusion was a timing issue, probably timing chain off by a tooth. I had checked the chain for stretch, and got some wierd results. He checked it and got a BTD result, but not 18*.
Shorten the story here, and I have forgotten most of the info, but I loosed the chain tensioner and carefully rolled the chain over a tooth. Never cut into it, just carefully rolled it tooth to tooth.
Timing fell right into place, after that it show about 4* of stretch, not the BTD as it did before. The wierd noises stopped and it ran better.
of course by then it had bent a valve, but that is a different story.

A friend has a 240D that was off by one tooth for years. The only problem the car had was, hard starting, so the owner rigged up a 24v starting system. Other than that it ran fine:confused:

That's good to know. I've always wanted to play around with different valve timing using offset keys to see what the torque curve, mileage does. Never knew how far I could safely.

Not to hijack this thread but how hard is it to install an offset key? My 240D has about 4 degrees of stretch...right at the point I would consider installing one I guess...can you just pull the sproket out enough to clear the key, pluck out the old one and drop a new one in or do you have to remove the chain and sprocket completely?

I removed the sprocket off the cam. Just attach a bungee cord to it and hang it from your hood (with chain attached of course). Make sure there is always tension on it and you'll be fine. I don't know if its possible to do without removing the sprocket but its not a big deal to take it off.

My 240 had 4 degrees of stretch also which prompted me to do this repair. Don't forget to correct your injection timing afterwards.

Scott

Thats the way I did mine. Zip-tie the chain to the sprocket and remove the tensioner from the side of the engine. You can use a bungee cord to keep upward tension on the sprocket if you are afraid of dropping it.

nhdoc,

I have peered at this before:

http://www.peachparts.com/shopforum/diesel-discussion/177638-how-install-camshaft-woodruff-offset-key-pics.html?highlight=woodruff+key+install

I am about 4 degrees off on my 82, and will probably attempt it at some point in the future.

-dd

Thanks...so if I understand, you remove the tensioner first and then take the sprocket off the cam, right? Otherwise the chain is probably too tight to move the sproket, I'd assume?

That link is helpful, I bookmarked it, thanks

Anyone thought of the crank-damper....?

Ive heard of engines where the outer ring containing the timing-marks, shifting in relation to the inner core, at the rubber interface.....

Maybe summit similar here....?

Does the 617 have any rubber? I don't recall seeing any

That's my write up! I forgot all about it.

Scott

Be careful not too loose the washer down the hole when removing the sprocket:eek: