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-   -   om617.952 no compression after rebuild. (http://www.peachparts.com/shopforum/diesel-discussion/398966-om617-952-no-compression-after-rebuild.html)

Maximan1 05-09-2019 11:27 PM

Quote:

Originally Posted by Diseasel300 (Post 3918620)
Barely. With as weak as that starter is, it should have a VERY noticeable change in pitch/cadence. Even on the 140PSI Jeep engines, they have a very distinct tone on each compression stroke. That's clearly missing here on an engine with 2x-3x the compression. Something funky going on.

Yeah, but if it's enough compression to slow the starter, it would be more than enough to move the needle on the gauge.

Compression would also be lower until the rings were seated. I'd say that sounds roughly normal for a weak starter on a zero mile engine.

Roverswap 05-15-2019 03:24 PM

Compression
 
I adjusted valves and rechecked compression. 120 on one and the rest between 30 and 60. I took the head to a new machine shop in town. He told me the head has cracks in and around the injector holes. Two of the exhaust seats would have to be repaired. The bad compression was caused by the first machine shop not doing the valve job correctly. I'm taking a om617.951 head to him tomorrow for testing. Fingers crossed, and thanks for all the help.

Sugar Bear 05-15-2019 04:20 PM

The compression test shows that the cylinder could not either make and/or hold pressure. By putting air in the cylinder you can determine where it leaks. We now know that some of the valves didn't seal. We don't know if the pistons and rings leak or seal. Since the head is removed, an option at this point would be to put a liquid into the cylinders to see if they seep down at similar rates to each other. An oil change would be recommended as this would dilute the oil.

One could also fashion a plate held over each cylinder to see if they hold vacuum.

Good luck!!!


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