1950 8n conplete engine rebuild only have 10# psi

tim haire

New User
everything inside new except cam and lifters machine shop said within specs. Could something be wrong inside governor where pressure is bleading off. I rebuilt this for my father 90 birthday as he had over 50 years it looks like new. I'm a good mechanic and i'm going nuts! Help!!!
 
everything inside new except cam and lifters machine shop said within specs. Could something be wrong inside governor where pressure is bleading off. I rebuilt this for my father 90 birthday as he had over 50 years it looks like new. I'm a good mechanic and i'm going nuts! Help!!!
If your saying only 10psi compression did you prelube every thing?? Are the valves set as they should be?? Did you have the timing gears off of the cam or crank shaft?? If you did are you sure you have it timed right. Gov has nothing to do with compression
 
Check for a broken spring or a stuck regulator plunger.

Or, if the governor requires an orifice on the lube line, and it got inadvertently replaced with a standard fitting, it might be pouring too much oil in the governor

How was the oil pressure before you took it apart?
 
Hi Tim, welcome to the forum. If you are talking about oil pressure, can you trust the gauge? I think Fritz in talking about the oil pressure relief spring and plunger. It's located behind that 15/16 inch nut on the front just up and to the right of the water pump.
 
everything inside new except cam and lifters machine shop said within specs. Could something be wrong inside governor where pressure is bleading off. I rebuilt this for my father 90 birthday as he had over 50 years it looks like new. I'm a good mechanic and i'm going nuts! Help!!!
Oil pressure or compression?
 
If your saying only 10psi compression did you prelube every thing?? Are the valves set as they should be?? Did you have the timing gears off of the cam or crank shaft?? If you did are you sure you have it timed right. Gov has nothing to do with compression
not compression oil pressure
 
Check for a broken spring or a stuck regulator plunger.

Or, if the governor requires an orifice on the lube line, and it got inadvertently replaced with a standard fitting, it might be pouring too much oil in the governor

How was the oil pressure before you took it apart?
new spring plunger good give me more info on governor orfice please
 
Hi Tim, welcome to the forum. If you are talking about oil pressure, can you trust the gauge? I think Fritz in talking about the oil pressure relief spring and plunger. It's located behind that 15/16 inch nut on the front just up and to the right of the water pump.
have put stewart warner guage still 10 psi
 
new spring plunger good give me more info on governor orfice please
I’m not sure if there is supposed to be one, but if there was, it would be right where the line goes into the housing, to spray oil on the parts. Early tractors did not have this, but you mentioned oil pressure and governor in the same sentence so I assumed your tractor is set up that way. The orifice I was referring to is in the elbow that the external oil line is attached to. If replaced with a standard fitting, this could cause a loss of oil pressure by creating a substantial leak.

You can test this theory by removing the line from the bottom of the oil filter and plugging the hole. If this was the problem you will see an increase in oil pressure.
IMG_0950.png
 
What oil viscosity do you have in there, and is this 10 psi shown when first started up, or after warming up? Oil pressure is always pretty low on the N's (do a search of these forums and you'll find lots of discussion about it), and oil viscosity makes a big difference. With 15-40 in my rebuilt engine, it's about 35 when cold, drops to anywhere from 8-12 when hot & working. Has been like this since I rebuilt it back in the mid 2000's and hasn't caused an issue. When my father changed oil to 10w30 one time it was waaay lower -barely registered on the gauge.
 
What oil viscosity do you have in there, and is this 10 psi shown when first started up, or after warming up? Oil pressure is always pretty low on the N's (do a search of these forums and you'll find lots of discussion about it), and oil viscosity makes a big difference. With 15-40 in my rebuilt engine, it's about 35 when cold, drops to anywhere from 8-12 when hot & working. Has been like this since I rebuilt it back in the mid 2000's and hasn't caused an issue. When my father changed oil to 10w30 one time it was waaay lower -barely registered on the gauge.
I put 10w30 for break in i'm going to block line to filter see reading if no change i'll change to heaver oil
 
I’m not sure if there is supposed to be one, but if there was, it would be right where the line goes into the housing, to spray oil on the parts. Early tractors did not have this, but you mentioned oil pressure and governor in the same sentence so I assumed your tractor is set up that way. The orifice I was referring to is in the elbow that the external oil line is attached to. If replaced with a standard fitting, this could cause a loss of oil pressure by creating a substantial leak.

You can test this theory by removing the line from the bottom of the oil filter and plugging the hole. If this was the problem you will see an increase in oil pressure.
View attachment 79292
did this no change
 
just blocked return line out of filter canister no change. Where can i be losing pressure anyone heard of block cracking internaly?
Did you rebuild the oil pump? There is a lot of history on this board about miss sized oil pump gears.
 
The oil pump in the early 1950 tractor have a thinner gear size than tractors with a S/N after 247571. In the early tractors there is less volume flow rate and lower oil pressures than with the later model 8Ns. (Expected)

The correct oil gauge for front mount distributor is 9N 9273A which is 0-50psi gauge. The 0-80 psi gauges used in later model 8Ns are not as accurate with the lower pressures, and may not read correct.

You may want to vent the line at the gauge as well.
 
OK someone tell me whats happinin? took governor line off filter an plugged no differance 10psi. Now took line off t block to filter put in plug have 25psi Whats goin on ???
 

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