LarryMaine
Member
Bought a 1957 850 this week, an improvement from the 2N I restored last year. I did an engine compression test and could use some help in diagnosis and plan of action. The test result are as follows, First No. is Cold Engine, Second No. is Cold Engine with a squirt of oil, Third No. is Hot Engine no oil. They are for cylinders moving from dash to radiator in a row (not firing order), Cyl 1 120/125/110, Cyl 2. 75/85/75, Cyl 3. 92/88/95, Cyl 4 107/91/102. No Oil in coolant, no water in oil. Plugs all have equal amounts of carbon, but not caked on too bad. No plug or insulator damage. No smoke in exhaust, even on cold start-up. Engine is covered in oil from years of use and probably bad gaskets. Oil pressure 50 lbs. Hours on what is probably the original proofmeter is 6900 hrs. Engine sounds fine, no rattle, pings, etc. No history on tractor other than it was a working tractor and ran fine on my purchase. No real rust, original hood, 801 replaced fenders and foot boards. WHY is hot engine compression lower than cold engine, I thought rings would expand when hot? What is typical reason for such a large difference between cylinders? Oil did not significantly improve compression. What is going on with Cylinder 2 (is this valves, rings, or other?) I assume no blown head gasket as fluid are not mixing. What should I do next, what can I expect, ie. full rebuild, just valves, valves & rings??? Thanks all, REALLY appreciate any suggestions, experiences, etc. Larry