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post #21 of Old 05-10-2012
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Re: Runaway Yanmar 2qm15 HELP!

Originally Posted by miamiz View Post
Thanks Paul for your help. The 2QM15 is a pretty simple glow plugs or turbos or anything. Just fuel, air and combustion (which makes this that more frustrating!). I did take the injector pump and have it rebuilt. Also I did do a garage analysis of the oil. Poured it into a glass jar and let it sit for a few days. There was no visible separation but there was muddy (cabon I assume) at the bottom when I dumped it out. Checking the crank case ventilation hose & housing is on my list of things to check. I'll try running disconnected. Just bought an oil pressure gauge so I'll get some reading on that too. Will also make some temporary injector shims to see if adding additional space will have any impact. I will also pull the head and drop the intake valves to see if I can see any oil residue. Theoretically, it should be dry right? Also ordered a new head gasket. The thought of pulling the engine the third time makes me want to learn to actually "sail" my boat! LOL
Depending on the condition of the engine some blow-by vapors may condense
and be visible in the intake manifold but I wouldn't think there should be puddles of oil anywhere. Intake valves should be fairly clean. If the pump/ governor assembly is all in one housing I guess you can assume it was properly re-built?? If you took out the cam maybe it wasn't re-installed in the right position although some cam drives I have seen are off center so you can only install them in the correct position but the cam marks and crank marks need to be aligned. I think that if the timing was very far off it wouldn't run
at all. The 3 to 4 second "breathing" thing has me puzzled? So far all I can think of is:

1. Bad pump/governor
2. Timing way off
3. Lube oil getting into the intake tract, if that is happening I think the engine would go beyond 3,500 RPM and eventually scatter. If it stops at 3,500 I would suspect the governor/"throttle" linkage or assembly is stuck on "full open"

If you don't have a really good detailed shop manual you should get one, well worth the cost. Let us know what you find. You may have too much faith that the pump was properly re-built? Just a thought?

Paul T
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