1949 Ford 8N: no oil pressure revisited

CFB

Member
Hello all,
it has been some time due to health and family issues, but now retired and most projects sort of up to date and now wanting to get my 8N working again so I can participate in my local tractor club who drives in parades.
Summary of what I did:
a. had good oil pressure when purchased about 8 years ago. That continued as I used it around the yard, but then it sat.
b. reading on forums, I successfully did that prime the oil pump through the oil relief valve in front of the engine.
c. Now my memory gets fuzzy. Since I got the pressure back, I changed the oil since I did not know when the previous owned did it. What I don't recall is if I did it cold or after I ran the engine to warm it up. I changed the oil filter too and I cleaned the air filter with new oil in it. There was a screen at the drain plug and it was clean. I felt for the pick up tube and it was tight or snug, no slop to it. I then drove it into the barn and it sat. I started it periodically throughout the next several months but then it sat.
d. I repeated the "prime the pump" routine, but this time not successful.

So before I try that prime the pump routine again, I have a few questions.
1. my Amish tractor repair shop said he would not put in that heavy weight into the engine. This worked for me (once) and others on the forum in the past, so is that little bit bad or only do it moderately? Could that have clogged any of the oil ports throughout the flow system?
2. I read where someone stretched the spring that is in the oil relief valve. how do I know if I should do that or not?
3. I disconnected the tube by the pressure gauge and nothing was coming out there. I followed that tube downward and disconnected it there and no oil was there either.
4. Any advantage to changing the oil again now?
5. How long can I safely run the engine to see if I get pressure?
6. JMOR, back in sept 2009 shared a great picture of the engine oil flow. In that picture, in the upper right, was a green garden sprayer, but I did not see an explanation as to what I could do with that? Was it to try and force pressure through the tubes to try and clear any clogs?
7. My last question is about trying to clear the flow tubes, if that is at all possible, how do you do that and at what spots do I enter that air pressure?

I hate to drop the oil pan, I know that is last resort. Maybe it sounds scarier that it is.

Thank you. Appreciate any insights.
CFB
 

1. 4 ounces in 5 quarts is trivial, imo.

4. not that i'm aware of.

6. it's a different method of getting oil to the pump. u use the sprayer to pump oil into the system.
 
Doesn't matter what oil is used to prime as long as it isn't so thin as to flow on thru & out of pump before you get it back together & start it. If you remove the relief plunger behind the spring, you can have a better opening for flow during priming. Just be sure to put it back afterwards or you won't have oil pressure!
 
a. had good oil pressure when purchased about 8 years ago. That continued as I used it around the yard, but then it sat.
Having good oil pressure is a good thing! Says a lot about the condition of the engine, not worn out, etc. Losing prime is unrelated to good oil pressure. Usually losing prime comes from an internal air leak somewhere in the oil system, oil pump, pick-up tube, etc.

c. There was a screen at the drain plug and it was clean. I felt for the pick up tube and it was tight or snug, no slop to it.
Good. Doesn't mean though, there isn't a crack or leak where the tube is brazed to the pump

d. I repeated the "prime the pump" routine, but this time not successful.
A lot of variables why it didn't take. I'd just try again.

So before I try that prime the pump routine again, I have a few questions.
1. my Amish tractor repair shop said he would not put in that heavy weight into the engine. This worked for me (once) and others on the forum in the past, so is that little bit bad or only do it moderately?
Already good answers to this. Don't worry about it.

Could that have clogged any of the oil ports throughout the flow system?
No, not unless the oil was filled with sand or the like.

2. I read where someone stretched the spring that is in the oil relief valve. how do I know if I should do that or not?
The pressure of the spring against the valve determines your opening or cracking point. This is what limits your pressure. Without the relief valve opening, you would build way too much pressure and it wouldn't be controlled. Engineers carefully determine spring length and tension to set oil pressure. DON'T STRETCH IT. If you don't like your spring for some reason, broken, fatigued, etc. replace it with the proper oem spring.

A weak spring will not cause loss of prime. It would cause lower oil pressure than a correct spring.

Sometimes, oil relief valve springs are "shimmed" with washers to increase pressure. This is usually outlined in a service manual, and I don't believe I've ever seen it regarding a 9N, 2N, or 8N engine.


3. I disconnected the tube by the pressure gauge and nothing was coming out there. I followed that tube downward and disconnected it there and no oil was there either.
No oil pressure = no oil flow. If you have lost your prime and have no oil pressure, I wouldn't expect any flow anywhere.

4. Any advantage to changing the oil again now?
Not really. Now if your old oil is junk & thin, it may help slightly, but changing the oil when there is sufficient good oil in there won't help.

5. How long can I safely run the engine to see if I get pressure?
Oil pressure should come up almost instantly, within a few seconds anyway. I wouldn’t run it more than say 10 seconds.

Often one can bring up oil pressure just by cranking over the engine.

7. My last question is about trying to clear the flow tubes, if that is at all possible, how do you do that and at what spots do I enter that air pressure?
If you had good pressure before and have kept the oil changed it's unlikely your oil tubes and galleys are clogged. Now if you said you hadn't changed the oil in years of hard running, and the oil was completely saturated with deposits, maybe, there could be some blockage. I wouldn't worry about that yet.



I hate to drop the oil pan, I know that is last resort. Maybe it sounds scarier that it is.
Drop the oil pan only when you are ready to remove the pump, which is part of the #1 main bearing cap. About all you could do then is inspect carefully for loose pick up tube, and rebuild the pump.

Extremely worn pumps usually still produce some oil pressure, albeit usually very low pressure. A worn pump alone shouldn't cause you to lose the prime.

Most tractors don't lose a prime even after sitting for years. It doesn't take much oil for the pump to prime. Now if it's sucking air... that's another story. Almost all 9N’s, 2N’s or 8N’s that keep losing prime have a loose pick-up tube or cracked brazing of the tube.

If it were me, I'd try priming the pump again, and running the tractor. Try starting again in a day or two and see if it has kept the prime, if so, try again in another couple of days. If it loses the prime each time, you will be dropping the pan.
 
Some engine are very stubborn. Sounds like you have one. You have no oil pressure. If you crank the engine severe damage can be done. To lessen this issue, try pulling the plugs and pull the tractor in 4th or 3rd gear to effect priming. This is much easier on the engine - no heat. It should prime in 50 feet. I wouldn't go much more than that.
 
Thank you for your comment. How do I know if this method worked. Does pressure register on the gauge even if engine is not started? Or after the 50 feet do I start it then to see if it worked? thanks.
 
(quoted from post at 10:32:33 09/09/17)
a. had good oil pressure when purchased about 8 years ago. That continued as I used it around the yard, but then it sat.
Having good oil pressure is a good thing! Says a lot about the condition of the engine, not worn out, etc. Losing prime is unrelated to good oil pressure. Usually losing prime comes from an internal air leak somewhere in the oil system, oil pump, pick-up tube, etc.

c. There was a screen at the drain plug and it was clean. I felt for the pick up tube and it was tight or snug, no slop to it.
Good. Doesn't mean though, there isn't a crack or leak where the tube is brazed to the pump

d. I repeated the "prime the pump" routine, but this time not successful.
A lot of variables why it didn't take. I'd just try again.

So before I try that prime the pump routine again, I have a few questions.
1. my Amish tractor repair shop said he would not put in that heavy weight into the engine. This worked for me (once) and others on the forum in the past, so is that little bit bad or only do it moderately?
Already good answers to this. Don't worry about it.

Could that have clogged any of the oil ports throughout the flow system?
No, not unless the oil was filled with sand or the like.

2. I read where someone stretched the spring that is in the oil relief valve. how do I know if I should do that or not?
The pressure of the spring against the valve determines your opening or cracking point. This is what limits your pressure. Without the relief valve opening, you would build way too much pressure and it wouldn't be controlled. Engineers carefully determine spring length and tension to set oil pressure. DON'T STRETCH IT. If you don't like your spring for some reason, broken, fatigued, etc. replace it with the proper oem spring.

A weak spring will not cause loss of prime. It would cause lower oil pressure than a correct spring.

Sometimes, oil relief valve springs are "shimmed" with washers to increase pressure. This is usually outlined in a service manual, and I don't believe I've ever seen it regarding a 9N, 2N, or 8N engine.


3. I disconnected the tube by the pressure gauge and nothing was coming out there. I followed that tube downward and disconnected it there and no oil was there either.
No oil pressure = no oil flow. If you have lost your prime and have no oil pressure, I wouldn't expect any flow anywhere.

4. Any advantage to changing the oil again now?
Not really. Now if your old oil is junk & thin, it may help slightly, but changing the oil when there is sufficient good oil in there won't help.

5. How long can I safely run the engine to see if I get pressure?
Oil pressure should come up almost instantly, within a few seconds anyway. I wouldn’t run it more than say 10 seconds.

Often one can bring up oil pressure just by cranking over the engine.

7. My last question is about trying to clear the flow tubes, if that is at all possible, how do you do that and at what spots do I enter that air pressure?
If you had good pressure before and have kept the oil changed it's unlikely your oil tubes and galleys are clogged. Now if you said you hadn't changed the oil in years of hard running, and the oil was completely saturated with deposits, maybe, there could be some blockage. I wouldn't worry about that yet.



I hate to drop the oil pan, I know that is last resort. Maybe it sounds scarier that it is.
Drop the oil pan only when you are ready to remove the pump, which is part of the #1 main bearing cap. About all you could do then is inspect carefully for loose pick up tube, and rebuild the pump.

Extremely worn pumps usually still produce some oil pressure, albeit usually very low pressure. A worn pump alone shouldn't cause you to lose the prime.

Most tractors don't lose a prime even after sitting for years. It doesn't take much oil for the pump to prime. Now if it's sucking air... that's another story. Almost all 9N’s, 2N’s or 8N’s that keep losing prime have a loose pick-up tube or cracked brazing of the tube.

If it were me, I'd try priming the pump again, and running the tractor. Try starting again in a day or two and see if it has kept the prime, if so, try again in another couple of days. If it loses the prime each time, you will be dropping the pan.
 


thank you for your thorough answers! They are all very helpful; most that I've not read before.
 
thanks for your quick reply.
I want to thank everyone who has responded, taking the time to help from you all is much appreciated. I am probably a week or two away from trying it, so any other insights are
appreciated. I hope I have good news to report.
 

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