8n Oil Pressure

[Baraboo13]

I'm only getting about 10psi at start up on my 8n on a rebuilt engine. First I had issues with low compression and the issue ended up being that the crankshaft was not timed properly with the camshaft, some good fellas from the forum helped me figure that out. Looking around this site today some people mentioned a oil relief valve, I pulled that nut out and there is no plunger or spring in there. I got this tractor from a guy that lost interest in the project, he told me he dropped off the engine at the engine building place and picked it up assembled when they were done and he just bolted back up to the rest of the tractor. He gave me the invoice for $2200 for the build. Looking at the invoice they even charged him for a FO4 manual but I don't know if they bother to look at it. My question is if the missing plunger and spring could be the issue with the low oil pressure or should I look elsewhere? I'm scared to even think what else could be wrong with this tractor, I figured if found a good since it had a rebuilt engine and I wouldn't have to mess with the engine but boy was I wrong.

 

[TheOldHokie]

(quoted from post at 20:26:22 12/29/18) I'm only getting about 10psi at start up on my 8n on a rebuilt engine. First I had issues with low compression and the issue ended up being that the crankshaft was not timed properly with the camshaft, some good fellas from the forum helped me figure that out. Looking around this site today some people mentioned a oil relief valve, I pulled that nut out and there is no plunger or spring in there. I got this tractor from a guy that lost interest in the project, he told me he dropped off the engine at the engine building place and picked it up assembled when they were done and he just bolted back up to the rest of the tractor. He gave me the invoice for $2200 for the build. Looking at the invoice they even charged him for a FO4 manual but I don't know if they bother to look at it. My question is if the missing plunger and spring could be the issue with the low oil pressure or should I look elsewhere? I'm scared to even think what else could be wrong with this tractor, I figured if found a good since it had a rebuilt engine and I wouldn't have to mess with the engine but boy was I wrong.

Without the plunger and spring you have a massive oil leak - I am surprised you get any pressure. Put the spring and plunger in and I expect you will see much higher pressure.

TOH

 

[Baraboo13]

(quoted from post at 19:53:42 12/29/18)

(quoted from post at 20:26:22 12/29/18) I'm only getting about 10psi at start up on my 8n on a rebuilt engine. First I had issues with low compression and the issue ended up being that the crankshaft was not timed properly with the camshaft, some good fellas from the forum helped me figure that out. Looking around this site today some people mentioned a oil relief valve, I pulled that nut out and there is no plunger or spring in there. I got this tractor from a guy that lost interest in the project, he told me he dropped off the engine at the engine building place and picked it up assembled when they were done and he just bolted back up to the rest of the tractor. He gave me the invoice for $2200 for the build. Looking at the invoice they even charged him for a FO4 manual but I don't know if they bother to look at it. My question is if the missing plunger and spring could be the issue with the low oil pressure or should I look elsewhere? I'm scared to even think what else could be wrong with this tractor, I figured if found a good since it had a rebuilt engine and I wouldn't have to mess with the engine but boy was I wrong.

Without the plunger and spring you have a massive oil leak - I am surprised you get any pressure. Put the spring and plunger in and I expect you will see much higher pressure.

I got the plunger and spring coming i will let you guys know how it goes when I get them. Thank you and have a happy new year

 

[Den N Ms]

Baraboo13,Yes that is your oil pressure problem,think of it as a garden hose running with no end on it.Plenty of volume but not much pressure,till you put your thumb over the end and then it has pressure.Get the plunger and spring put in and let us know what you have cold and then hot.Some replacement springs were too stiff and made too much pressure when hot,like 60 - 90 lbs way to much!Hopefully the one you get will be correct.like releasing at around 50 lbs tops.

 

[Bob]

Be aware that certain aftermarket springs and/or plungers are not good copies of the originals, and are not equivalent in function.

Several on here suggest getting those parts from a CNH dealer.

Hopefully, they will chime in with their experiences and tell you what parts to avoid.

 

[Den N Ms]

much pressure when hot,I meant much pressure when cold, That can even blow out gaskets on the filter or the top leak bad when cold.

 

[TheOldHokie]

(quoted from post at 01:34:05 12/30/18) Be aware that certain aftermarket springs and/or plungers are not good copies of the originals, and are not equivalent in function.

Several on here suggest getting those parts from a CNH dealer.

Hopefully, they will chime in with their experiences and tell you what parts to avoid.

The only specification I have ever seen for the oil pressure relief spring is in the shop manual for the Ford 120 CID industrial manual. It specifies 44-46 ounces (2.75/2.87 pounds) force @ 1.4" compressed length. I removed the spring from my 8N and measured it as shown below. When tested it produced 34 ounces (2.13 pounds) @ 1.4" compressed length. This tractor is pretty much unmolested and I expect that is the original factory spring. In any event I do know it works fine and cold oil pressure is roughly 50+ PSI which drops to 30-35 PSI when hot. Using that spring as a benchmark these springs from McMaster should be work fine. They have a spring rate of 3.41 lb/in and a free length of 2" which yields 33 oz (2.05 pounds) force at 1.4" compressed length.

Compression Springs from McMaster

Obviously I have not tested them and the proof is in the pudding.

TOH

 

[Tom Massachusetts]

When I got my oil pump problem fixed, I only had 10# pressure hot or cold. I bought a used OEM off the internet, replaced it, now I have 45# cold and 15# hot idle. The previous owner had replaced the spring with an after market set.

 

[Baraboo13]

I got the plunger and spring coming from this website hopefully they are good, i will let you guys know how it goes.
Thank you again guys

 

[Baraboo13]

Hi guys

I got the spring and plunger in place and the oil pressure is way to high the gauge maxes out at 50psi and the pressure is way past the 50psi mark. So my guess is that the spring is too stiff?
Any idea where i can get a better spring, I got mine from this site and it says Denis Carpenter on the package have any of you guys used those before. Also i adjusted my air compressor to 40psi and pushed a rubber tipped blow gun to the gauge and when pull the trigger it reads right around 40psi thats the only way that occurred to make sure that the gauge is working properly. Any help would be greatly appreciated.

 

[TheOldHokie]

(quoted from post at 19:55:13 01/13/19) Hi guys

I got the spring and plunger in place and the oil pressure is way to high the gauge maxes out at 50psi and the pressure is way past the 50psi mark. So my guess is that the spring is too stiff?
Any idea where i can get a better spring, I got mine from this site and it says Denis Carpenter on the package have any of you guys used those before. Also i adjusted my air compressor to 40psi and pushed a rubber tipped blow gun to the gauge and when pull the trigger it reads right around 40psi thats the only way that occurred to make sure that the gauge is working properly. Any help would be greatly appreciated.

Try the ones in the link I posted earlier. Cheap experiment.

TOH

 

[Baraboo13]

So I got the new spring in place today and I'm getting 30psi oil pressure at startup. If I compare this one with the one i had before i would this one takes about half the effort ro compress compared to the first i had. Do you think 30psi oil pressure?
If this is a good oil pressure I have five of them left and I could spare a few of them if anybody needs one.
Thank you

 

[TheOldHokie]

(quoted from post at 17:53:52 01/20/19) So I got the new spring in place today and I'm getting 30psi oil pressure at startup. If I compare this one with the one i had before i would this one takes about half the effort ro compress compared to the first i had. Do you think 30psi oil pressure?
If this is a good oil pressure I have five of them left and I could spare a few of them if anybody needs one.
Thank you

That is a little low as a cold relief pressure. Does it drop off when the engine warms up? If so then I would say good to go. If not its cracking below your hot pressure. That's really ok too since 30 PSI is better than average but I would be inclined to shim the spring a bit to see if you can boost the hot pressure a bit.

TOH

 

[Baraboo13]

I didn't get the tractor up to operating temperature since i don't have my cooling system hooked up. It was about -1°f yesterday so i don't know if that would influence the the reading with the oil being so cold. So i only ran the tractor for about 30 seconds. How shouls I shim the spring? What come to mind would be to cut a small section of another spring and put it in the plunger first followed by the full length spring.
Thank you for the help

 

[Baraboo13]

I didn't get the tractor up to operating temperature since i don't have my cooling system hooked up. It was about -1°f yesterday so i don't know if that would influence the the reading with the oil being so cold. So i only ran the tractor for about 30 seconds. How shouls I shim the spring? What come to mind would be to cut a small section of another spring and put it in the plunger first followed by the full length spring.
Thank you for the help

 

[Baraboo13]

I didn't get the tractor up to operating temperature since i don't have my cooling system hooked up. It was about -1°f yesterday so i don't know if that would influence the the reading with the oil being so cold. So i only ran the tractor for about 30 seconds. How shouls I shim the spring? What come to mind would be to cut a small section of another spring and put it in the plunger first followed by the full length spring.
Thank you for the help

 

[Baraboo13]

I didn't get the tractor up to operating temperature since i don't have my cooling system hooked up. It was about -1°f yesterday so i don't know if that would influence the the reading with the oil being so cold. So i only ran the tractor for about 30 seconds. How shouls I shim the spring? What come to mind would be to cut a small section of another spring and put it in the plunger first followed by the full length spring.
Thank you for the help

 

[Baraboo13]

I didn't get the tractor up to operating temperature since i don't have my cooling system hooked up. It was about -1° F yesterday so i don't know if that would influence the the reading with the oil being so cold. So i only ran the tractor for about 30 seconds. How shouls I shim the spring? What come to mind would be to cut a small section of another spring and put it in the plunger first followed by the full length spring.
Thank you for the help