It was just tired already, but its running better after MMO in the cylinders for days.
well here is the low down
this is an engine from a 81 TDt that was wrecked. Rolled over.
I thought it was dead. it may still be, but it runs like it always has since i have had it.
I changed the oil recently and only got around 5 quarts maybe a little less out of the engine.
The engine started running rough and i figured it was just a clogged fuel filter, or the valve lash was off. well both of those needed fixing. I figured I would repair my oil leak at the oil filter tower to block seal. I did all the work in the same job.
Once i got it all back together, valve lash done and the fuel bled. I start it and it runs horribly. Worse than ever. Its shaking all over the place and smoking. So I check the basics like air in the fuel and valves adj. No avail.
I decide to check the compression and bummer only like 180 on #5 and 230 on #4. i put a tablespoon or so of oil in and compression went up. Extra bummer. After checking those problem cylinders i just got bummed and gave up.
Since i was using a POS Hfreight compression tester I decided to let a trusted indy do a leakdown test. On Cyl #1,2,3 compression was good 4 and 5 had approximately 75 % leakage.
I'm bummed thinking i ran it out of oil. It never lost pressure though as far as I know. Indy tells me to put MMO in the Cylinders and let it sit for a few days. I put one bottle each cylinder #4 and 5 and come back to blow it out by cranking without injectors, and nothing comes out. It went into the crank case.
Well I drive it for a bit and nothing is better. then i give up since I had shoulder surgery coming up.
So six and a half weeks later i go start it and it smokes a bunch. I take it for a drive and it runs smoothly no missing. I'm thinking well its probably just the biodiesel making it smoother. so I put in diesel #2 and still runs good
I decide to check compression. I check only #5 which was the worst . It was pretty much dead. So i have the compression tester hooked up, I crank it, the motor sputters for a few seconds because the other injectors are hooked up and the compression goes all the way to 420 Psi. I check it again with no sputter and its back down to 180 or so.
I check the other good cylinder #1 and it goes all the way to 500 or something with the same type of sputtering of the engine.
So I believe this may be the same testing method i used when i first tested the engine making me believe it was a like new motor when really it was tired.
Well none the less, it is back to the same running condition that it was when i installed the engine. The idle is a little shaky but it is clearly running on all cylinders. I loosen injector lines to check.
One other thing is the lack of major blow-by. I take off the oil lid and it barely moves. If i remove it all together some blow-by is apparent but nothing major. Oil does not come out when it is idleing with the cap off.
So I'm going to take it out on a long drive after changing the oil to get the MMO out. Maybe It is not over after all. What do you think.

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Chris
84 280sl
82 300d euro