9n oil pump

1943ford9n

New User
Not sure how this works? I have a 9n with a fresh engine rebuild. I keep losing oil pressure after stopping and starting about 6 times. I prime it and then it is good.
 
Welcome to the forums. Have you checked the pickup tube?
With a fresh engine rebuild, did you rebuild the pump or replace it?
 
1943ford9n.......not certain whatcha complainin' about. You do hafft prime the oilpump after an engine rebuild. Most just stuff the oil pump fulla lite grease like vasoline. Howsomevers.......iff'n it won't keep its prime, then more'n'likely, yer sheet metal suck'em-up tube hazza crack in it. Which means droppin' the pan and removing the oil pump and tube fer closer inspection. Yes, you kenn fixx the crack with brazing........Dell
 
You may have excessive clearance between the gears and the pump cover. You did replace the gasket between the cover and the gears didn't you?
 
"yes i check the tub and yes the machine shop rebuilt the oil pump."

Good, at least it was rebuilt and not replaced without a line bore.
How did you check the pickup tube and why didn't the machine shop do it?
 
what do you mean why didnt the machine shop do it? I inspected it before it was installed and then i now drained the oil and checked it by making sure it was not loose by moving it from the drain plug.
 
(quoted from post at 23:23:40 04/08/17) what do you mean why didnt the machine shop do it? I inspected it before it was installed and then i now drained the oil and checked it by making sure it was not loose by moving it from the drain plug.

It doesn't have to be loose to leak. A pin hole or crack in the tube will cause just as much problem as a loose tube. You also need to check for leaks in the tube and/or around the cover.

A leak would be the good news. The bad news is the loss of prime is also a symptom of a worn out pump. The housing can and does wear to the point where new gears and a bushing won't restore the internal clearances. That commonly happens when it was run for an extended period of time with a worn out shaft bushing which allows the drive gear to cock sideways. If the gear has been running cocked sideways it will rub against and eat into the housing and cover. You should always inspect that area of the housing as well as the cover plate for signs of scoring and wear before replacing the gears and bushing.

This is a too common issue with new rebuilds and a royal PITA to deal with after the fact. I have come to the conclusion that a new pump and line bore should be part of any major overhaul. It also allows you to upgrade to the higher volume pump which was a major improvement.

TOH.
 
If the gear has been running cocked sideways it will rub against and eat into the housing and cover. You should always inspect that area of the housing as well as the cover plate for signs of scoring and wear before replacing the gears and bushing.


TOH.

Amen .

I have 5 blocks sitting in the corner . I took the pumps to my machinist buddy and we installed new bushings and custom bored each bushing to fit its used shaft . Every pick up tube needed the flat side resurfaced . I will test for leak down before I install them . I am on the fence about switching to the 3/4" pump for my personal 8N . I am leaning to keeping the 9/16" pump and running 10-30 synthetic . I would like to use the money saved towards something that was designed for a front end loader , either Old and Blue or Newer and Orange .
 
(quoted from post at 11:46:40 04/09/17)
If the gear has been running cocked sideways it will rub against and eat into the housing and cover. You should always inspect that area of the housing as well as the cover plate for signs of scoring and wear before replacing the gears and bushing.


TOH.

Amen .

I have 5 blocks sitting in the corner . I took the pumps to my machinist buddy and we installed new bushings and custom bored each bushing to fit its used shaft . Every pick up tube needed the flat side resurfaced . I will test for leak down before I install them . I am on the fence about switching to the 3/4" pump for my personal 8N . I am leaning to keeping the 9/16" pump and running 10-30 synthetic . I would like to use the money saved towards something that was designed for a front end loader , either Old and Blue or Newer and Orange .

The pump gear is a press fit on the end of the shaft. How can you go undersize on the bushing and still get the end of the shaft through it?

TOH
 
well it has lost primp again. I primed it last night and it was good 35. Started this afternoon and still good 35. Ran the tractor for about 45 min with a spring tooth on it. When hot it was at 20. Turned tractor off and started again and only 5 and now zero. What should i start with first?? Oil pump?
 
The pump gear is a press fit on the end of the shaft. How can you go undersize on the bushing and still get the end of the shaft through it?

TOH

I dropped them off and picked them up after they were done so I will have to ASSUME that the shafts were not worn more than a few thousandths , enough to make it tough assembling but tight once installed ? I know he built parts for Boeing for decades and would have told me if any needed parts as that was a doable option .
 
is there anything special i have to do to install a new 3/4 oil pump instead of the 9/16 pump that is original? Thanks for the help.
 
(quoted from post at 15:12:43 04/09/17)
The pump gear is a press fit on the end of the shaft. How can you go undersize on the bushing and still get the end of the shaft through it?

TOH

I dropped them off and picked them up after they were done so I will have to ASSUME that the shafts were not worn more than a few thousandths , enough to make it tough assembling but tight once installed ? I know he built parts for Boeing for decades and would have told me if any needed parts as that was a doable option .

As many of these as I have done you'd think I would have remembered that the gear end of the shaft is considerably smaller than the shank. :oops: I'll blame it on a senior moment....

TOH
 
(quoted from post at 15:47:20 04/09/17) is there anything special i have to do to install a new 3/4 oil pump instead of the 9/16 pump that is original? Thanks for the help.

Yes - replacing the pump regardless of which gear width you elect to use is a "big deal". The mains have to be align honed to match the new pump to the block and the other two caps which is why it's much easier to do it as part of an overhaul rather than afterwards.

TOH
 
(quoted from post at 14:32:27 04/09/17) well it has lost primp again. I primed it last night and it was good 35. Started this afternoon and still good 35. Ran the tractor for about 45 min with a spring tooth on it. When hot it was at 20. Turned tractor off and started again and only 5 and now zero. What should i start with first?? Oil pump?

This is that royal PITA part I was talking about. Everything points to the oil pump but you can't be 100% sure. Replacing the oil pump means a complete disassembly of the engine and trip to the machine shop....

TOH
 
This is that royal PITA part I was talking about. Everything points to the oil pump but you can't be 100% sure.

TOH

I am thinking ( i am taking a break from sweating ) that if the oil pump is tight , it would not matter if the pick up tube had a pin hole and the oil level in the tube dropped down to the level in the pan . The tight oil pump should have enough oil to stay primed ? I would have to say it IS in the pump .

I also think that today's synthetics on a 9/16" pump would supply sufficient lubrication to the whole motor , but also would have the ability to lose the prime on a worn pump quicker than conventional oil ? Just a thought . If I post enough I can be a Guru and won't have to ask questions , LOL :wink:
 
"If I post enough I can be a Guru and won't have to ask questions"

Well, not quite. I've posted enough to be a "guru" but I still ask questions.
The combined knowledge here is far greater than I will ever have.
That's what makes it such a great forum site! :)
 

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