H Farmall Oil Pressure...

Can someone tell me what develops the oil pressure in an H? Is it the cam bearings, main bearings, rod bearings, or???

I finally have to admit it, the oil pressure on my H isn"t what is should be. It starts out at 45 pounds on a cold startup with fresh SAE 30 oil, but with the engine fully warmed up will barely hit 10 pounds at full throttle. This is a 1952 H, my father-in-law bought it in 1958 and it"s been in the family ever since. I"ve owned it since my FIL died in 1980. I"ve never done anything but normal maintenance and I don"t recall my FIL having anything major done to it, so it"s possible the engine has never been gone into.

It still doesn"t smoke or use oil, compression sounds even across the board, so I"m wondering if replacing main and rod bearings would help, or if I need to go further. Any input would be appreciated.

Thanks in advance.

Good question. My H does the same thing, when its first started the needle is in the run side, after 20 minutes its on the idle side at wot.?

Obviously, the oil pump builds the oil flow/pressure and it gets leaked away through the rod, main, and cam bearings, lubing and cooling them as it flows.

As those parts wear, it all adds up. Some of the smaller Farmalls are known to warp the oilpump cover, causing an oil leak there which only leaks worse as the oil thins when warm. I'm sure others with more "H" experience than I will chime in and tell us if that could be a factor here.

Old-time mechanics would sometimes drop the oilpan and then pressurize the oiling system from an external source and look to see which bearings were passing the most oil.

After checking out the oilpump, you can drop a couple of rod and main caps and Plastigage the bearings to see what the oil clearance is.

I had an M with low oil presure and after doing some work on the oil pump which did not improve the presure I found out all I needed was a new oil presure gauge.

Could be worn cam bearings. Hal

if very limited use just add some really heavy oil. This is not for heavy work just playing with tractor

I replaced the guage. Same pressure.

pick up an oil pan gasket and an oil pump cover gasket next time your near a dealer. drop the pan and then pull the lower cover off the pump. there is a spring and bypass that may drop out along with one of the pump gears. check the surface of the pump cover for wear. if you can see where the gears have been wearing in the cover, use a piece of glass for a flat surface and lay some emery cloth on it and sand the cover smooth again. while the pan is off, you can also get a peek at the mains and rod bearings too. napa should have plasti-gauge, you can see what kind of bearing clearance you have. i'd bet the oil pump cover is wore.

The pump needs to be pulled. The gasket on the cover is probably got a spot where it lets oil leak. Or the pump is getting worn out. Yes the bearings could cause this, but is much more likely the pump on an H or M.

(quoted from post at 07:08:39 11/08/10) pick up an oil pan gasket and an oil pump cover gasket next time your near a dealer. drop the pan and then pull the lower cover off the pump. there is a spring and bypass that may drop out along with one of the pump gears. check the surface of the pump cover for wear. if you can see where the gears have been wearing in the cover, use a piece of glass for a flat surface and lay some emery cloth on it and sand the cover smooth again. while the pan is off, you can also get a peek at the mains and rod bearings too. napa should have plasti-gauge, you can see what kind of bearing clearance you have. i'd bet the oil pump cover is wore.

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I found it much easier to just pull the whole pump. There's only one bolt holding it in, and then you can turn it upside down, hold it in a bench vise and go to work on the bottom without risk of any parts just falling out.

Be advised, there is a heavy spring under that cover, and it will work against you when removing the 4 bolts that hold the cover on.

That's where I'll start. Somehow, I never thought of the oil pump. And the oil pan is easy to drop on those.

(quoted from post at 08:14:57 11/08/10) That's where I'll start. Somehow, I never thought of the oil pump. And the oil pan is easy to drop on those.

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I did mine last fall just before I had to start pushing snow. I improved it a whole bunch, but I didn't take quite enough material off that cover, so while the oil pressure now is satisfactory, it still is not where I want it to be. I think I'll scrounge through the used parts pile and see If I can find an oil pump that is not quite so worn, and start from there.

These pumps wear out. The shaft wears and if bad enough wears into the housing. Have replaced many shafts over the years and usually the housing is ok even where the shaft is worn. End clearance is critical of course, I start with out any gasket, if it binds at all I add one shim gasket at a time. Covers on the H don't usually warp much but can easily be trued up with a flat surface and sandpaper. Also, look at the relief valve. If it is worn or wrong one installed. Over the years the parts some how got mixed up, and a lot of relief valve plungers were installed during routine overhauls that is incorrect. The correct one is straight all the way from one end to the other. Wrong one has a slightly smaller diameter with shoulder . That one will run about 45 psi and correct one will run about 65 to 70 psi full throttle and good engine. First M I ever overhauled at dealership , customer was complaining about oil pressure and oil consumption as dealer had done a ring job on it winter before. It had that wrong regulator valve in it and of course it got new sleeves then but was an inframe overhaul so no new cam bearings or other goodies. I found several more of them in both the H's nd M's over the years including my dad's 52 H which is mine now.

I took the cover off the pump, ground it smooth on a surface grinder, cleaned up the gears. Works great.