Timing and overheating

[danders]

Here's my situation. Was installing a new timing chain on my '82 300SD and managed in the process to drop the chain on the injection pump side into the engine. After several tense hours and many curse words, I was able to fish it out. I really had to pull hard to get it to meet the other end of the chain back on the camshaft gear. Started the engine up and it runs but rough. It also overheats, pegging the temp needle. Now, it could be that I had it so advanced due to chain stretch, that timing is now way advanced. If that is the case, will several degrees of advancement make the engine run very hot? Otherwise, I am wondering if dropping the chain and then pulling it back up I could have jumped a tooth on the injection pump gear causing timing to be so far off it overheats.

Anyone ever have this happen to them before? If I managed to get the pump timing off, I'll have to pull it and reset. I have pulled the pump before, a couple of years ago, and it is the toughest mechanical job I've ever had to do on a car so am not looking forward to having to repeat it. Mainly due to that impossible to get to bolt/bracket on the back.

Thanks for advice anyone has on this.

danders
'82 300sd 297kmi.

[RVR]

It sounds as if the IP has "jumped timing" and it will have to
be timed once again. My best guess is: the timing chain has
slipped on the centrifugal governor teeth that engage the chain.
Thus causing you all this grief.

Don't ask me how i know this.

RR
in OKC/OK

[danders]

I checked injection pump timing today and found it was about 9 degrees retarded...I set to 24 degrees BTDC. So it appears pump timing did not jump. Still runs way too hot, between 110 and 120 degrees. Think I will take the water pump out to make sure nothing dropped into the cooling system when I had the thermostat housing off. Is it possible that I have a bubble in my cooling system since it was partially drained and this is keeping water from pumping through the cooling system?

I will also check cam chain timing again but after I installed the chain, it appeared to be right on, cam mark lined up with TDC. If the cam had jumped a tooth, would the engine still run?

Danders
'82 300sd

[gsxr]

Ugh. You MUST check and verify that the crank, cam, and IP are all timed correctly. Cam & crank should be dead on with a new chain, which I assume you have checked. Next step is the IP. It must be WAY off to do what you say it's doing. If you're lucky, your OM617 may be able to use the lock tool, which is a huge help in setting timing (and/or pulling the pump & re-inserting). Look for a 17mm hex-head plug on the lower/middle of the pump... if you see one, your pump can use the tool. If you don't, you're stuck with the old methods (and the "wet" method of adjusting start of delivery). Here's a photo of the lock tool:




HTH,

[danders]

Thanks for the responses. I just checked cam timing and when the mark on the cam is lined up, engine timing is at 0 degrees. As I mentioned before, injection timing is at 24 BTDC.

[gsxr]

Whoops! Sorry about that - I missed the updated post. If everything is timed in spec, my guess is a coolant bubble, and/or a stuck-closed thermostat. If everything is in time, that is NOT the cause of your overheating.

I'm a little confused as to why the engine runs rough. Is it still doing that? Cold, hot, all RPM's?

[kerry]

These engines are notorious for getting an airlock in them when refilling with coolant. Fill with the car pointed uphill on a steep slope. Fill the engine via the top radiator hose. Run the engine with the heat on full blast after filling. This is no guarantee there will be no bubble. I'm not sure what exactly causes the problems in the sedan, but the 617 in my 409d does not seem to have the air bubble problem.

[RVR]

Danders,

Put your thermostat in a pan of boiling water to confirm
it is opening properly.
HTH

RR
OKC/OK

Good luck