46 farmall h oil pressure

Make sure your oil gauge is good. If so, check the oil pump a little further before tearing the engine down again.

First, and I'm not trying to be a smart a** here, check the pump cover gasket. If you replaced it by making a new gasket out of regular gasket material you will have too much clearance between the cover and the gears and your oil pressure will be nill. The correct gasket is only 0.05" thick.

If your good with the gasket, next I would check the clearance on the oil pump gears, both between the body and the gears and lash between the gears. If they are out of spec, put new gears in (NOS gears are available). Also be sure that the shaft does not have any side play, if it does, you need a different pump body and/or the shaft is worn excessively.

Finally, (and this the the easiest fix) be sure that the gear end play isn't excessive as it will cut away at the pump cover. This happens a lot and causes oil to bypsss gears reducing pressure. If you find galling on the cover, measure the play between the pump body and the oil pump cam drive gear (write it down) if out of spec, knock out the pin, remove the woodruff key and pull the cam drive gear. Add shims (McMaster and Carr has them)to get the end play back into spec. Next have the pump cover milled flat, or if you have nothing but time on your hands, get a piece of plate glass, some grinding compound and do it yourself. Finally order a new gasket and reassemble.

Despite the fact that the pump is bathed in oil they do wear. I bougt three used pumps before I found a good pump body, and all had gears out of spec. I replace the gears, got the end play into spec and put it in my rebuilt H - oil pressure shot to 70 psi and hardly moves.

Once you know the pump is good, and the problem persists, it's time to think about the cam bearings.

Good luck

It may be time to start thinking cam bearings, but if it were me I'd go through the oil pump one more time before going to the expense and trouble. It would really tick me off if I put in new bearings and still have the problem.

E-mail me if you have questions.

Yes, check the gap where the gear teeth mesh with each other. I'll try to post you the clearance values from the service manual tonight, but 0.010 I'm pretty sure is too much.

Once you compare all of the clearance values for your pump with the correct specs, you will know for sure if this is your problem. The reason I'm so keen on the pump is that from talking with people who rebuild Farmall engines frequently, I get the impression (and it is just a feeling) that cam bearings don't take as much wear and tear as the rods and mains for example, and so are not the usual culprit for low oil pressure.

Stick with it you'll get it figured out soon.

diametral clearance of gears in pump body - 0.005-0.008
Body gears endplay - 0.003-0.006
Body gears backlash - 0.003-0.006

These clearances will give "like-new" performance, however, a pump 0.002 or so out of spec will still give better oild pressure than you describe.

Can I assume from your last e-mail that you didn't put the new rod and main bearins in? If not you may want to check the rod and main clearances again.

2) Endplay can be measured with the cover off. Push the the shaft gear assembly up from the bottom. Use a feeler guage to measure the gap created between the oil pump drive pinion (the top gear that meshes with the cam)and the pump body. This measure is often out of spec. The result is that the pump gears can now contact the oil pump cover plate, cutting circular indentations into the plate through which oil is allowed to escape producing low oil pressure. Look at the bottom of the cover plate if it isn't smooth or nearly so, you have excessive endplay.

Three things must be done to affect a fix: 1)eliminate the endplay by removing the drive pinion and place the appropriate shims under it to make up excessive play, 2) have the coverplat refaced so it is perfectly smooth, 3)replace the gasket with a new 0.005" thick gasket. This seems to be the most common reason for oil pressure loss at the pump. You must fix the endplay to fix the problem - smoothing the cover is not enough.

3) Gear backlash: that is the gap between the drive and idler gear teeth when they are meshed together. You already know that yours are out of spec by over 100%. The only fix here is to replace the gears. Some people get into spec, or close enough to get pretty good oil pressure by replacing only the idler gear. The pinion drive gear is a bit of a pain to remove, and some folks don't like to mess with it. If you have to fix endplay, however, you may as well replace both gears if you can afford it.

To find NOS parts try posting a new message asking where others go for parts, and also put an add in the classifieds. I got mine sometime back and I can't remember the gentleman's name, but his screen name is NOSIH. The other alternative is to find a good used pump.

Even if your cam bearings have to be replaced in the end (and I hope not), you will want a great functioning pump to protect all those new parts you worked so hard to get in. So either way the pump is time and money well spent.

Good luck, let us know how it goes.