Long

So, I pulled the engine and took it apart today, expecting shot rod and/or main bearings. Guess what? Rod bearings look excellent, mains look good. Lots of bearing material, some scratches, some wear on the mains, but it all looks good. I don't have any way to measure the clearances, but they can't be too bad. Also, (although it doesn't have anything to do with oil pressure) the pistons had minimal wear and there was no ridge at all in the cylinders.

The oil pump gears looked good (3/4" gears).

So, why do you think that the oil pressure went bad? Is it possible that the cam bearing surfaces are bad? Or maybe just the oil pump?

I'm thinking about having the cylinders measured and if they and the pistons are OK, then just going back with standard size piston rings. (4-ring pistons). The crank will need to be turned due to ridges on it.

Any suggestions?

No reason to check compression. The engine ran OK (burned some oil) but compression had nothing to do with oil pressure. I know I have 4 ring pistons because they're laying on my work bench right now. I'm familiar with plastigauge, used it on many engine overhauls. It's just that i've never had this problem when the engine's bearings look this good.

To everyone: I will check the oil pickup tube right now and see if it's loose. The pressure relief spring and valve were OK, no debris and the oil pressure gauge is also OK - it's a mechanical gauge and tested fine.

Since I have this baby apart, i'm going to go ahead and send everything out to the machine shop - new cylinder liners, main and rod bearins, valves, and valve guides. Oh yes, and a new oil pump - just in case. This tractor lasted me ten years so far with very little maintenance, so at least now i'll know what's inside. All it takes is $$$ that I don't have. :-)

Thanks for all of the replies. I appreciate it.

8NLvr

How do you know that you have 4-ring pistons? I believe they stopped installing them in 1949 and sidemount engines started in mid 1950. Anyways, 3-ring aluminum pistons are better and are recommend for ALL years (39-52) N-Engines as replacements.

You can't tell a d*mn thing about an oil pump just by looking at it, ya gotta get the ol'feeler gauges out. Your camshaft does NOT have renewable bearings and are NOT likely to be the cause of your oil pressure loss. And yes, your most likely cause of prime loss is the oilpickup tube. Zane sez you can sweat silversolder it to reseal where the tube fits the oilpump.

As for your crankshaft, time to get the ol'plasti-gage out. You have to ask for it at real autoparts stores, it comes with instructions. That is how you measure your crankshaft bearing journals. And then if too "wide" clearance, hav'em turned to replacement standards..... ....respectfully, Dell