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1942 Ford G 6 cylinder oil pump


edhd58

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okay i need help. The thing was running fine until last Wednesday. That is when it stopped having oil pressure. All was good until that day. I checked the gauge, it's fine. I checked the oil passage the gauge was connected to, again - fine. Today I pulled the pump, which just happens to be part of the front main bearing cap, so I cant just go buy another. Here are my observations of the oil pump. The shaft the drive (big) gear is on has some slop (you can rock the shaft) where it goes through the housing. The drive gear can also be moved up and down a very slight amount. When I took the pump apart there is a gasket between the body parts, I know it's supposed to be there, but I can also put the pump back together without it and spin the pump easily.

My questions are,

1) should the drive gear have ANY wobble to it where it comes through the housing.

2) there has to be a small amount of "end" play movement for it to rotate freely does't it?

3) with the gasket removed that tightens up the end gaps in the gears which should make it work even better shouldn't it?

4) There is a video I am trying to link to that shows I have to spin the pump very very fast before it will pick up liquid, at this time I am just using water.

Anyone know how to remedy this problem??

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UPDATE -- I located and talked to a couple older vehicle mechanics close by. Both said there apears to be no reason for this thing to not be working. What I have tried is putting it back together without the gasket between the two parts, thegears still spin fine. I figure this closes up the gap at the end of the gears reducing area for oil to be getting out of the gears. I have 5W30 oil in it and one of the fellows I talked to says this is too thin for this old style pump. with teh wear on the housing I need to have at least 20w50. Tomorow I will take the pump to the machien shop that did teh work and see if I can get them to take the drive gear out so I can get a new bushing installed to eliminate the side play. I also want to see if they can machine the housing 0.003 so i can ptu the housing back together with the gasket in place, if not I'll use rtv sealer and do away with the gasket.

Latest weird thing. I put it back together, no gasket no rtv sealer, tightened the bolts good, got some 30w oil in a pan and using a drill spun the pump at 1400 rom -- the speed of the drill. Darned if the silly thing didn't pick up oil and sqirt it all over me before I could stop the drill. Now I have to also say that I did use a cloth wrapped tube a clean some crud out of the oil pick up tube. but I drained the tube then spun it several times and it worked every time. Once I hit 1400 rpm which would be a fast idle it was pumping oil. I just wonder if it wasnt all due to thin oil?? I don't know.

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I do want to use the gasket, but also want minimum clearance between the gears and the pump body, everything spins easy with no gasket. . That is why if they can't machine the body to allow the use of a gasket and still keep the clearance to a minimum I may use sealer. I am also going to look in to Ford TO-30 oil pump gears. The old Ford tractors have this same setup, the gears may be interchangeable. Just one more avenue to explore.

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UPDATE -- took the pump assembly to a local tractor guy thats been around forever. He knows this style pump well from talking to others that know him. According to him this pump has to have close tolerances. The gap I have now 0.015 between the gears and the body is too much. I need to have the body machined so the gears/body has 0.005 clearance when asembled with a gasket. Took the assembly to a local machine shop and for $100 I should have it back tomorow, they are only machining the body I will have to do a little work on the gears and reassmemble. According to the tractor guy when this is done I will have all the oil flow the car will need.

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Its done!!!!!! yeahhhhhhhhhh!!!!!!! okay here the short version of a long story. had to machine the body of the housing to 0.005 lower than the top of the used gear. Had to machine the new inner gear to match the old inner gear. The gasket is 0.010 which then puts the other half of the body 0.005 above both gears. Now the pump shaft bushing and the inner gears are no where to be found. At least I can't find them anywhere, which is why the pump housing had to be machined. The tractor guy said this set up is the same as a 9N Ford tractor. So I called the local tractor parts supplier and ask if he has a rebuild pump kit for a 9N Ford tractor. He does. Turns out the pump shaft bushing is exactly what I need. The pump is now reconditioned and reinstalled. At idle I now have 50 pounds of pressure. NOw I am waiting for new gaskets to arrive so I can reassemble everything, repaint the engine and reinstall it.

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Good news that you now have oil pressure, but what, up until last wednesday, was the pump putting out for pressure? And, most importantly, why did it suddenly have NO oil pressure ?? The pump did not suddenly get all that wear and clearance.

My thoughts are that when you cleaned out the pickup tube you pushed out some hard chunk of sludge, old RTV gasket sealer, or a hunk of old gasket.. Something that stopped the worn and weak pump from being able to suck up the oil from the pan.

When a pump is above the level of oil in an engine, it is common practice when installing a new or dry pump to pack the oil pump gear spaces with some form of heavy oil or grease.. I use regular vaseline, it is petroleum jelly, and mixes immediately with the oil.

I'd carefully clean the oil pan and screen, to assure you don't have another ''something'' plug up the pickup. IF that is what happened.

Normal clearances for most gear type pumps are around .005-.007" tip of gear to pump housing, and just a few thousandths end play on the gears. A too thick pump cover gasket can cause a pump to have excessive gear endplay and lower pressure than normal. I've made my own gasket from a very good quality paper, like the oil-paper some parts, bearings etc are wrapped in. This paper is very strong, and is not affected by oil. The pump and pump cover surfaces must be smooth and flat.. I usually 'lap' them on a heavy piece of glass on 400 or 600 grit carborundum paper, aka 'wet and dry' paper. This paper is much thinner than the thinnest gasket material normally available. I think the paper is around .003-.004" thick.

GLong

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GLong, all those thoughts ran through me head too. Like I said earlier, nobody including myself could really see why it stopped pushing oil. I did push some sludge out of the pick-up tube but not enough I didn't think to stop oil from flowing. Hopefully the gaskets will be here tomorrow and I can out it all back together. I did make sure the screen is clean and extra thoroughly cleaned the pan. All I can do now is wait and hope, hope nothing goes wrong again.

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Guest Al Brass

Generally speaking, a gear pump is a very forgiving piece of equipment and will continue to work, even when very, very worn. Like GLong, I think there might well be something else that caused your problem and I do hope you've corrected it. You may never know just what it was.

Al

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New, close clearances and just a film of oil in a gear pump will pull/suck oil up from the pan, But give it thin oil that drained down, loose clearances, so much more than a 'film' of oil is needed to seal gaps, and add in a bunch of thick sludge in the supply tube or on the pickup screen. Then you have a scenario where the pump would do fine, at least as good as it did the last time it ran, but it just can't develop the suction to pull oil through the clogged or restricted pickup tube and screen.

It's definitely good that you now have a mostly rebuilt pump, with much closer clearances.

But, my money is on the thought that if you had just cleaned the pan, the pickup tube and screen, and put a little thick oil or vaseline on the gears, it would have drawn up the oil, and worked as well as before.

Al: I've often been amazed at how worn an oil pump can be, and still develop respectable oil pressure. It makes me think about a nice tight-clearance pump, and slightly thick oil or cold oil,, the pressure the pump can create must be measured in the !00's of psi. The pressure-relief valves or pressure regulators on our cars have a real job to to on a cold start up !! I remember an aftermarket high volume oil pump I put on a VW engine in a Dune Buggy, it would overwhelm the oil pressure relief valve, and would 'balloon' the spin on oil filter. The first time I saw that I was really shook up, thinking that it could have split the filter canister, and dumped all the oil in about 5 seconds. and then my VERY expensive crankshaft, camshaft, etc would have been trashed in moments..

GLong

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I am going to believe in the thought that something got picked up in the ick-up tube. the new gaskets arrived yesterday, I have the engine all back together and running. Idle at 190 degrees is 45+ lbs pressure. If you shut it off and wait for the pressure to go to 0 and crank it the pressure starts climbing before it starts to run. Everything was cleaned really well before it got assembled the first time, and again this time. Oh well, one of those things I'll probably never know why what happened did happen.

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With the pan and oil pickup tube and screen clean, you've done everything that can be done to make sure the pump won't have any restrictions on the intake/suction side. I think you are good to go for a few hundred thousand miles !! :-)

GLong

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