8n oil pressure

mawc

Member
i have an 8n that the oil pressure was 40 cold and barely 0 warmed up at idle. at full throttle I could get about 15. I put a new spring in it out front and now I have the oil pressure pegged when cold and idle my gauge goes to 80 and warmed up at idle 10. it is a factory gauge it was in it when I got it. does it should like I need a rebuild?
 
I just had my 8N rebuilt by a professional motor builder and have similar results with the oil pressure readings. I have double checked the readings with another gauge and the readings were the same. Everything was new in the rebuild and the best reason that I came up with, after talking to the builder, for the reading is that as the motor, and oil, warm to temp, that the clearances in the oil pump and bearings change, the result is lower pressure at the gage because of where the measurement is taken at. That reading is at the very near end of the oil flow. All the oil pressure is being lost as the oil is doing its job before it gets to the gage and is being drained back into the oil pan. Now if the readings were taken before the oil was drained through the rest of the motor the readings would be different. Newer motors get the reading as soon as the oil comes out of the oil pump, and before all the loss is done in the motor bearings. The oil filter on these old motors is the last thing the oil goes through, and it only has a 80 Thousand passage to the governor gears to keep them lubed. This is also why there is not oil gages on some older,and smaller motors.
 
Yep, I concur with Teddy - gauge is working fine, your engine is worn out and it's time for a tear down/rebuild. If you run the tractor for a few hours, shut it down, let it cool, then check the oil level. If lower than when you started, proves the case in point. I would not keep running it like that as eventual damage can be done. FWIW, don't buy any new parts until you do have the block stripped down and you know exactly what parts you will need. N-Series models 9N, 2N, and early 8Ns (all Ford vehicles prior to early/mid-1950 for that matter) used the STAR (*) symbol before and after the serial number to indicate that steel sleeves were used in the cylinders. When FORD went to cast iron cylinder liners, the stars were replaced with a Diamond (<>) symbol. Now, that means nothing today since they no longer make steel sleeves anyway. Only cast iron cylinder liners are made and sold. Also, some guys removed the sleeves, bored out the cylinders for the larger Mercury pistons, and used no sleeves whatsoever. That's why I say don't buy any new parts until you know what you'll need. I also suggest you use a good machine shop and mechanic who knows these old Fords. Many "mechanics" take shortcuts often unknown to you usually because they don't know and understand the original configuration.

Tim *PloughNman* Daley(MI)
 
I'd like to ask a question for oldman570. If what your engine re-builder fed er told you. How come the engines showed good oil pressure when they were new?
 
(quoted from post at 12:59:05 03/16/18) I'd like to ask a question for oldman570. If what your engine re-builder fed er told you. How come the engines showed good oil pressure when they were new?

And why do other people have Ns that show decent oil pressure when warm?
 
(quoted from post at 11:43:43 03/15/18) i have an 8n that the oil pressure was 40 cold and barely 0 warmed up at idle. at full throttle I could get about 15. I put a new spring in it out front and now I have the oil pressure pegged when cold and idle my gauge goes to 80 and warmed up at idle 10. it is a factory gauge it was in it when I got it. does it should like I need a rebuild?
0 psi AT A WARM IDLE IS GOOD. What do you have at working RPMs when warm?
 
(quoted from post at 11:43:43 03/15/18) i have an 8n that the oil pressure was 40 cold and barely 0 warmed up at idle. at full throttle I could get about 15. I put a new spring in it out front and now I have the oil pressure pegged when cold and idle my gauge goes to 80 and warmed up at idle 10. it is a factory gauge it was in it when I got it. does it should like I need a rebuild?
f thee relief valve is doing its job, the needle should never be pegged. IMHO
 
This is from the instruction book that my dad got with our 1947 Ford 2n tractor. Looks like 15 to 30 is about right for the 9n 2n and early 8ns.
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