8N oil pump replacement

[Jeremiah's Tractors]

Hi I have a 8N that has a bad oil pump (it does not have oil pressure unless you prime it before you start it). I think the oil pump is beyond repair. When you put the new one in do you have to do anything to the main bearing cap part of it? Also maybe why it wasn't working was because they used Permatex black gasket sealer instead of the normal thin gasket.

 

[BobTx]

My understanding is that the block will have to go to a machine shop and the new bearing cap lined bored. BobTx

 

[wore out]

Hi I have a 8N that has a bad oil pump (it does not have oil pressure unless you prime it before you start it). I think the oil pump is beyond repair. When you put the new one in do you have to do anything to the main bearing cap part of it? Also maybe why it wasn't working was because they used Permatex black gasket sealer instead of the normal thin gasket.

Upon WHAT are you basing the statement "I think the oil pump is beyond repair"?

Looks to me like there's a THICK gasket in amongst that black goo?

 

[Jeremiah's Tractors]

My understanding is that the block will have to go to a machine shop and the new bearing cap lined bored. BobTx

That is what I thought

 

[Jeremiah's Tractors]

Upon WHAT are you basing the statement "I think the oil pump is beyond repair"?

Looks to me like there's a THICK gasket in amongst that black goo?

I mean the wear marks on the surface of the pickup tube side of the oil pump(you can feel a lip on the surface). Yes, they actually did use a gasket with the sealer.

 

[used red MN]

I mean the wear marks on the surface of the pickup tube side of the oil pump(you can feel a lip on the surface). Yes, they actually did use a gasket with the sealer.

You need to do more research on what can be done to assure that the oil pump you have cannot be reused. Search Ford 8N low oil
pressure threads on here. I am not a Ford guy and have never had an 8N engine apart, I do know that placing that thick gasket on that oil pump cover was a major bobble by whoever worked on it. Those covers can be hand sanded down flat with wet/dry sandpaper on a plate glass.
YT 8N oil pressure thread For starters look at the replies by Hobo.NC in this YT thread. He might split a lot of hairs but there is good base knowledge given.

 

[Dan]

I would try to fix this one. Wear on the cover is normal and can be sanded down as stated above. Get a quality rebuild kit and give it a go. There has been threads showing these new rebuild kit gears are not as uniform in size as they are supposed to be, and I believe there are also questions on the gasket thickness if I am remembering correctly so I would search the forums for this and do some research. Also, a new oil pump will probably come out of spec anyway since most parts seem to come from the land of almost right - I would trust an old original before a brand new one. These old engines are very tolerant to wear and being out of spec, but the oil pump isn't one of those areas.

If you spend the time and effort this rebuilt oil pump will outlast you.

 

[soaked]

Hi JT
Would be great to know what size pump does your 8n have, and
how worn is the pump housing itself?
Pics of the pump would be helpful too.

When the bushing begins to wear the wobbily gear can begin to chew the leading and trailing section of the housing.
Ive experimented a couple times, and tried leaving the old .724 - .725 wide gears, and just cut a new bushing with OPT20 jig. Both had some scuffing on the housing, and both had better pressure. At the time, they got the thick gasket, as that was what was on hand. If not ran for a week, might take 10 long seconds to prime. Ran 30-35 psi hot, throttled up. Next one gets the permatex aviation gasket maker, and no paper gasket.

 

[Jim in LA]

Hi I have a 8N that has a bad oil pump (it does not have oil pressure unless you prime it before you start it). I think the oil pump is beyond repair. When you put the new one in do you have to do anything to the main bearing cap part of it? Also maybe why it wasn't working was because they used Permatex black gasket sealer instead of the normal thin gaske

Hi I have a 8N that has a bad oil pump (it does not have oil pressure unless you prime it before you start it). I think the oil pump is beyond repair. When you put the new one in do you have to do anything to the main bearing cap part of it? Also maybe why it wasn't working was because they used Permatex black gasket sealer instead of the normal thin gasket.

That gasket is way too thick. do you have noticeable play in the gears. My '49 had a lot of play in it when I rebuilt the engine 25# cold pressure and 10 or less when hot. I purchased the gear, bushing and gasket set from here andhad machine shop rebuild the pum. the guy messed the bushing up on the first attemp and got it dead on the second time, I could prime the pump holding it in my hand and spin it and it would shooe the oil abount 10 feet. The tractor has 30+ cold and around 20 hot now. The kit usually includes two paper gaskets. tolerances are very close.

 

[Non-farmer]

I hope Dan (the Old Hokie) is ok. He knows a ton about the oil pump. It worries me to not see him chime in here. Hope you're alright, Dan

 

[Jeremiah's Tractors]

You need to do more research on what can be done to assure that the oil pump you have cannot be reused. Search Ford 8N low oil
pressure threads on here. I am not a Ford guy and have never had an 8N engine apart, I do know that placing that thick gasket on that oil pump cover was a major bobble by whoever worked on it. Those covers can be hand sanded down flat with wet/dry sandpaper on a plate glass.
YT 8N oil pressure thread For starters look at the replies by Hobo.NC in this YT thread. He might split a lot of hairs but there is good base knowledge given.

After further look at it I think I should be able to rebuild it. Also what is a plate glass?

 

[Jeremiah's Tractors]

I would try to fix this one. Wear on the cover is normal and can be sanded down as stated above. Get a quality rebuild kit and give it a go. There has been threads showing these new rebuild kit gears are not as uniform in size as they are supposed to be, and I believe there are also questions on the gasket thickness if I am remembering correctly so I would search the forums for this and do some research. Also, a new oil pump will probably come out of spec anyway since most parts seem to come from the land of almost right - I would trust an old original before a brand new one. These old engines are very tolerant to wear and being out of spec, but the oil pump isn't one of those areas.

If you spend the time and effort this rebuilt oil pump will outlast you.

Yes, I think I will rebuild it .Thanks for your input.

 

[Jeremiah's Tractors]

Hi JT
Would be great to know what size pump does your 8n have, and
how worn is the pump housing itself?
Pics of the pump would be helpful too.

When the bushing begins to wear the wobbily gear can begin to chew the leading and trailing section of the housing.
Ive experimented a couple times, and tried leaving the old .724 - .725 wide gears, and just cut a new bushing with OPT20 jig. Both had some scuffing on the housing, and both had better pressure. At the time, they got the thick gasket, as that was what was on hand. If not ran for a week, might take 10 long seconds to prime. Ran 30-35 psi hot, throttled up. Next one gets the permatex aviation gasket maker, and no paper gasket.

As to what size it is, I don't know (I didn't know there was more then one size). I don't think the pump housing is too worn to be used. The gear does wobble some. Also there no scuffing on the housing form the gear.

 

[Jeremiah's Tractors]

That gasket is way too thick. do you have noticeable play in the gears. My '49 had a lot of play in it when I rebuilt the engine 25# cold pressure and 10 or less when hot. I purchased the gear, bushing and gasket set from here andhad machine shop rebuild the pum. the guy messed the bushing up on the first attemp and got it dead on the second time, I could prime the pump holding it in my hand and spin it and it would shooe the oil abount 10 feet. The tractor has 30+ cold and around 20 hot now. The kit usually includes two paper gaskets. tolerances are very close.

I was wondering if the gasket was to thick. yes there is play in the gears. Mine has about 30 psi cold pressure 2 - 10 when hot. Thank for your input.

 

[wore out]

Hi I have a 8N that has a bad oil pump (it does not have oil pressure unless you prime it before you start it). I think the oil pump is beyond repair. When you put the new one in do you have to do anything to the main bearing cap part of it? Also maybe why it wasn't working was because they used Permatex black gasket sealer instead of the normal thin gasket.

When the bushing and shaft wear the gears are forced into contact with the pump housing opposite the pressure side and the housing is worn away meaning that the pump will never be as "good as new" even if the bushing, shaft, and gears are replaced. If the wear to the housing is great rnough the pump is junk.

In your photo it APPEARS there is such wear to the housing that has actually raised metal at the pump cover mounting area.

If that is the case the gear will have worn unevenly into the machined area at the "front" of the gear chamber, as well.

 

[used red MN]

After further look at it I think I should be able to rebuild it. Also what is a plate glass?

I would define it as any glass 3/16” thick or more. If you have a piece of flat steel 1/4” thick 6x6 square would probably work. Also a window pane laid on a 3/4 plywood on a flat workbench would also work.

 

[Non-farmer]

Mine has about 30 psi cold pressure 2 - 10 when hot.

30 PSI is somewhat lower than i'd like to seen but still usable. The number 2 is the one that scares me. I've read some say 5 or more when warmed up is even ok.

Mine starts out at about 38 psi and drops to 20 when hot. My local auto parts guy (we're in farm country here, and he knows tractors well) told me that was fine, and said no need to mess with pulling everything apart with those numbers. His take was that my mains were still good. Sure seems like he was right, because i did an in-frame rebulid (basically new pistons, sleeves, and rod bearings) and i still have 38 -> 20 10 years later.

One major difference is that mine only lost prime once, when I dropped the oil pan to do the rebuild. Otherwise i still have 38 pounds every time i start it, no priming needed. I think wore out has a good eye and makes a good point about that visible wear at the near end in the pic.

 

[Jeremiah's Tractors]

When the bushing and shaft wear the gears are forced into contact with the pump housing opposite the pressure side and the housing is worn away meaning that the pump will never be as "good as new" even if the bushing, shaft, and gears are replaced. If the wear to the housing is great rnough the pump is junk.

In your photo it APPEARS there is such wear to the housing that has actually raised metal at the pump cover mounting area.

If that is the case the gear will have worn unevenly into the machined area at the "front" of the gear chamber, as well.

Do you think it is to worn to be used? I can measure it with a feeler gauge so you know how big the gap is. Also I think the gear teeth are worn so that makes the gap bigger

 

[Jim in LA]

I just looked at oil pump parts and kits on the parts section and 1948-1952 oil pump with 3/4" gear set pump overhaul kit is $62.00 and the oil pump body is$165.00 When my Dad rebuilt the '49 engine in1966 the tractor shop mechanic only had access to a good used oil pump and my Dad said it did have some play in the main gear. We always added a can of STP at every oil change.we used that tractor fromm '66 to 2017 about three months before he passed away. The tractor smoked preety bad and had a leaky head gasket but still prduced working oil pressure.

 

[Non-farmer]

Jim, mine smoked horribly from both ends when I got it. I had to rebuild it to fix that. Glad I did. It was only an in-frame rebuild, so not too pricy or time-consuming. Sure glad I did it. It had plenty of oil pressure but it kept forcing me to refill what had burned away. That got old in a hurry - that, and breathing the smoke coming out of the oil fill tube.

The right arm of my 3 point is still black.