cscott719
New member
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- Denver, CO
I have the DN2M/LPW2 engine from one of these that I acquired several years ago. I used it to build a home brew generator, which has been working reliably for the past 2 years. A month ago, it had a hard start condition, and would only fire on one cylinder. After a bit of tinkering, doing nothing significant, it started and ran fine on both cylinders. Since then, I had the same thing happen a couple of times. I use this machine nearly every weekend to run equipment out in the barn. After some reading on this site, I found some articles mentioning that high oil pressure would cause the lifters to pump up and hydraulically lock, preventing the valves from seating. This results in loss of compression at the least, and valve to piston contact at the worst. I went back out, and paid more attention to how it sounded when cranking, and realized it only had compression on one cylinder. When it did start, the RPMs would never increase past about 500 or so (no tach, I adjust speed with a frequency meter), which when running on one cylinder, was not enough to keep it running. Oil pressure was about 75 psi, the book calls for less than 30 psi. I did not do a compression test, but I suspect one cylinder has zero or close to it due to the valves sticking open, and the other has low compression, just enough that it hits, barely. I pulled off the valve covers, and I cannot spin the push rods by hand regardless of position on cam lobe. I also noted that while it was not completely dry in the rocker box, it did seem that it was not getting a lot of oil. I drained the oil, removed the side cover (door, as the Brits call it) and removed the oil pressure relief valve. By the way, there was some sludge in the bottom, but no filings or anyting magnetic in the crank case. I disassembled the valve, which was clean inside, and full of oil. the spring and plunger seems to move freely without binding. I cleaned it all up and put everything back together using 10W40, as it is cold here and the manual says it is good to I think about 60 degrees or so ambient. I started the engine without the valve covers. It started and ran as it should, hitting on 2 cylinders with enough power to pump the air compressor back up, but there was very little if any oil spraying from the rocker sockets where the push rods seat. I looked at the LPW2 service manual, and it does leave some to be desired. Evidently, the pump pulls oil through the screen, then through the filter, then to the main bearings. Then goes to the rods, and is slung around to everything else. So, evidently no pressurized oil to the cam bearings. But there is another passage that feeds pressurized oil to the lifters. It appears that the relief valve is not bypassing enough or at all, causing the high oil pressure, which is locking the lifters, preventing the valves from closing. But that does not explain the lack of oil through the push rods to the rockers. My experience is with automotive engines, and very little on diesels. so it is likely that I am missing something here. But it seems that the rockers should get more oil then they are. I don't want to remove the heads because of the lack of new head gaskets, but I will look for some today if necessary. Today, my plan is to remove the relief valve again and check it over. and then to remove the pushrods and make sure they are not clogged up. Hopefully, they are, and cleaning them up will allow better oil flow to the rockers. My question to you all is have you seen this before, and what was done to fix it? Also, does anybody have a line on parts for these engines, specifically top end gaskets and the oil pressure relief valve? Does anybody recommend running diesel fuel in the crankcase to clean out the oil passages? If not, what would you use? Thanks to all, you are a wealth of knowledge.
