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Universal Diesel Compression Test
I have a 1982 Universal Diesel 5411 which was showing low compression. I hauled the engine and installed new piston rings and a new head gasket (of course). Additionally, the raw water cooled engine cylinder head was almost rusted through to the cylinder head bolts. I was able to find a fresh water engine for which I paid too much. The donor engine had signs of being run pretty hard and the exhaust valves were just in specs.. Since I don't do long range cruising anymore, I didn't change the exhaust valves.
Today I did a compression test and found the following: #1 cylinder - 210 psi. #2 cylinder - 345 psi.. Both cylinders showed no significant leak down of pressure after 40 seconds. Also, while the engine was in operation last season, there was no unusual vibration either at idle or high power, which one would clearing expect if the compression was that far off. I had an engine with 15% compression differential that vibrated more.
I'm thinking that the number 1 cylinder exhaust valve may not be seating properly, or the head gasket is releasing any pressure over 210 psi.. I'm taking the head to a machine shop and doing the things regarding block and head surfacing, as well as the valves, that I should have done last season. Any thoughts as to why the gross difference in the compression readings? Thanks.