Tim101

Member
HI.
I am going to look at a engine for MF 65 gas, G176. I am thinking of performing a compression test. What PSI would be acceptable. What PSI is not acceptable. I know the cylinders should be within about 10 percent or somewhat close to each other not 30 or 40 PSI apart. Been a long time since I have even done a compression test.
Any other suggestions to look for while looking at engine. Breather tube on valve cover for blow by?
I bought a 58 MF65 with thrown rod. Mechanics report has broken rod and cam. I have not had the engine apart to see if block is any good.
Thanks for any help.
 
By the time to do all sorts of 'diagnostics' on an engine on the floor, you can tear it all apart and give it a rebuild for a couple hundred more.
80 or 90 pounds is getting low, but why? rings? seats? Tear it apart now, no better time than when it is out of the tractor already.
Practice on your blown engine first!
 
you can put oil in cylinders to tell if its rings the pressure will go up. but like Tony says easier to rebuild while out of the tractor. then more than likely the tractor will out live you LOL
Ypop
 
Hi
The engine will be in the tractor so I can run it and look at it not on the floor. I don't want to buy a rebuilder as I have one.( which could be so damaged that it is not worth the cost of rebuilding)
80 to 90 psi is low.
A good average 120 to 140 PSI.??
Help please.
This is what I bought, if I have to I will part it out.
Thanks
massey65.jpg
 
One thing you can do on a compression test is to test the cylinders dry (I think around 140 psi should be normal). Then you could try a wet compression test, remove the compression gauge, put a little bit of oil in the cylinder (a cap full of oil from a 1 quart bottle of engine oil) will be plenty, put the compression gauge back on the cylinder, and test it again. If the pressure goes up on the wet test by 10 psi or more the piston rings aren't sealing. Another test is a leak down test, it will give a better idea of how good the engine is.
 

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