Compression numbers on my '82 300d w/ <100k miles on the clock are as follows:

Cylinder Bar PSI
1 16 232
2 18 261
3 16 232
4 19 276
5 13 189

Car has sat for extended periods of time here and there and I am thinking that the rings are all gummed up. I was thinking of pulling the injectors and dumping either mystery oil, ATF, and/or SeaFoam on top of each cylinder and letting it sit for a couple of days to try and free the rings up. There is a good amount of blow-by as well. What opinions are out there as to the best way to go about un-gumming the rings? This car just doesn't have enough miles on it to show these types of low compression numbers.

 

Marvel Mystrey Oil is cheap and appears to work. Here is another thread from another forum.
Marvel MM oil results sticky rings

The Marvel Mystrey Oil Soak cured my hazy Gray Smoke that I had all the time due to the Volvo Diesel sitting 1 year with out runing and then running it with a Thermostat that would not allow the Engine to come up to temp for 6 months.

What ever you put in be sure to crank the Engine and blow out any excess Oil (with Glow Plugs or Injectors out) to prevent a hydraulic lock.
Also the MM Oil soak need time to do the job. I soaked 1 week and added more and soked for 3 days.
Change the Oil after the soak as no one recommends runninga Diesel with the MM Oil in the Oil.

 

thank you for your responses. nope, never have ran WVO and never will. a friend of mine said that SeaFoam will also work pretty well. Heard and good or bad about it?

 

thx. Forced. i sure will. we are doing a wet test today to be sure where the compression loss is coming from. actually, i am hoping that all of this is valve related only. i sure don't want to have to do a bottom-end rebuild on the condition that the MMO wouldn't work.

 

Wet test showed no leaks on the top end, so the valves are fine. 3-day cylinder soak is complete. Compression returned to 20+ bar across all cylinders. Final compression test at 80 celcius is tomorrow. At this point, I am extremely happy with this news! I will update with final compression numbers when I get them.

 

Sorry to crash the thread but....
Why are you not supposed to use MMO in a diesel? I put 8-10 ounces in my SDL and it helped quite a noisy lifter. I left it in there for about a month until the next oil change. It did not seem to affect anything else. Just curious. I have used MMO and Seafoam in just about every vehicle I have ever owned.

John