8N oil pressure

zuhnc

Member
Location
Macks Creek, MO
I recently purchased an oil filter conversion kit - cartridge type as originally installed to a spin-on type. Ran it for a while with 10W30 dino oil, as I had recently also re-ringed the engine, seal replacement, etc. Oil pressure hot at 1850 RPM was about 15 PSI, and hot idle was down near zero. After running this oil for about 20 hours, I wanted to change it and install the 20W50 synthetic I normally use in this engine. Oil pressure before the engine work, with the 20W50, was 25 PSI cold or hot, idle or operating speed.

I changed the oil and filter. On startup, oil cold, pressure was 20 PSI. I found this odd, especially with the thicker weight oil and being cold. The only change from before engine work to after was the conversion kit. I decided to investigate. The oil path is through the original canister filter, through the tiny hole in the center of the canister filter tube, and thence to the governor. I measured that hole and found it to be 0.060" in diameter. I removed the conversion kit, and removed the center adapter the filter attaches to. That adapter does have an orifice in it, but that orifice was 0.090" in diameter, 50% larger than the original canister filter hole. That translates into 4 times the area, and will allow quite a bit more oil through, especially when hot.

I drilled that orifice out so a piece of 3/16" brass rod could be pressed it it, and then drilled that brass rod for a 0.065" diameter orifice (closest drill bit to 0.060" I had). I reassembled all the components and reinstalled the adapter to the engine. Now I have 25 PSI oil pressure, cold at idle, and 45 PSI pressure at 1850 RPM.

I have yet to operate the tractor, under a load (brush cutter), to get everything hot enough and up to temperature. A lot of rain here, and too wet to mow.

So, low oil pressure issues might be related to that orifice in the original oil filter canister, if the engine is otherwise in good condition. Or, if a conversion from canister-type to spin-on has been done, the orifice in the conversion adapter might be incorrect.

I will further update this post when the ground becomes dry enough to mow some pastures. zuhnc
 
Thanks for the tip zuhnc. I've had oil pressure problems on my 2N ever since I rebuilt it. It doesn't get a lot of work, so I've never really got into it. But that is something fairly easy to check. Mine doesn't have the oil line to the governor though.
 
Update - After about 8.8 miles of mowing pastures today, at 1850 RPM, 1st gear, 5' Bush Hog (tm), thick tall grass, the oil pressure was 25 PSI. At 600 RPM, pressure was 15 PSI. Keep in mind the only new parts I installed on the re-ring were rings and main and rod bearings. All tolerances were within specifications, but on the upper end, so the lower oil pressure with reduced RPM I can live with.

It seems that the orifice in the bypass filter canister, or an orifice elsewhere in the bypass system, contribute somewhat to maintaining oil pressure.

I should machine another adapter with a smaller orifice (maybe 0.055" or 0.050") to see what happens to the oil pressure. I will have to monitor and/or measure the amount of oil bypassed into the governor. Although those engines without an oil line to the governor don't seem to have any governor issues.

I did have a slight overheat issue though; the tall grass and weeds clogged the radiator fins :oops:, and I lost about 1/2 cup of coolant. Cleaned and proceeded to finish that pasture and one other partially. Getting late, and dinner was ready. Salmon, rice and home-made coleslaw; yummy.

I will have (a day or two) a pasture-mowing video on my You-Tube channel for those that are interested. zuhnc
 
Another update - I posted incorrect information on my first update. The RPM is 1250, and not 1850 as I reported (thinking generators here; the good ones run at 1860 no-load). Pressure is correct at both RPM's.

Video is on my You-tube channel now - Chris Zuhn. zuhnc
 
What does Hank Ford’s biblical writings say the oil pressure allowed tolerances are?
Hank Ford built me a tractor which, without me doing a thing to the oil filter canister, gives me excellent pressure, between 40 psi cold and 20 hot. not bad for an engine that's older than i am. i'm not a huge fan of Henry, but he got that one right.
 
Hank Ford built me a tractor which, without me doing a thing to the oil filter canister, gives me excellent pressure, between 40 psi cold and 20 hot. not bad for an engine that's older than i am. i'm not a huge fan of Henry, but he got that one right.
Hello again SD! Do tell, what is the model of this fine example of modern ingenuity? I added some info to your post on Alerts in Site Comments
Your “Alerts” post
I like that “Mosquito Headquarters” not sure where that is but good old MinneSO.ta I am sure is in the running! :oops:
 
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Another update - I posted incorrect information on my first update. The RPM is 1250, and not 1850 as I reported (thinking generators here; the good ones run at 1860 no-load). Pressure is correct at both RPM's.

Video is on my You-tube channel now - Chris Zuhn. zuhnc
I hung window screening behind the grill, in front of the radiator. Slowed down the plugging of the radiator.
 
Thanks. I had 1/4" hardware cloth in front of the radiator, mounted on the bumper. Little clogging with that, but at the time I did not have a normal grill on the tractor. I obtained one and installed it, with the hardware cloth. Seems that the air flow brings stuff up from under that grill (front axle/pulley area) into the radiator, due to the bottom radius of the grill extending down a bit.

My next mowing I will take the grill off and reinstall the hardware cloth and see what happens. If it doesn't clog I will put a baffle under the grill to reduce any air coming from under there (front axle area) and try again.
 
I bought one of those Radiator Genie sets several years ago and they work really well. 8N radiators are easily accessible unlike some John Deeres and a water hose with good pressure should suffice.
 
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Another update - I posted incorrect information on my first update. The RPM is 1250, and not 1850 as I reported (thinking generators here; the good ones run at 1860 no-load). Pressure is correct at both RPM's.

Video is on my You-tube channel now - Chris Zuhn. zuhnc
I have a question. I rebuilt my 8n engine. All tolerances are within spec. My oil pressure at startup is about 60psi, verified with an independent gauge, then at running temp at idle, it is about 5 psi. I pulled the pan and checked rod and main bearings and oil pump, good. I rechecked the torque, good. After some thought, I have not checked the cam clearances. Would that affect oil pressure? What can I do about it? There aren't any cam bearings. Thanks.
 
I have a question. I rebuilt my 8n engine. All tolerances are within spec. My oil pressure at startup is about 60psi, verified with an independent gauge, then at running temp at idle, it is about 5 psi. I pulled the pan and checked rod and main bearings and oil pump, good. I rechecked the torque, good. After some thought, I have not checked the cam clearances. Would that affect oil pressure? What can I do about it? There aren't any cam bearings. Thanks.
I would start my own thread with the question, you'll get more response.
 
I have a question. I rebuilt my 8n engine. All tolerances are within spec. My oil pressure at startup is about 60psi, verified with an independent gauge, then at running temp at idle, it is about 5 psi. I pulled the pan and checked rod and main bearings and oil pump, good. I rechecked the torque, good. After some thought, I have not checked the cam clearances. Would that affect oil pressure? What can I do about it? There aren't any cam bearings. Thanks.
Obviously ALL of the clearances are not correct.

My first suspicion would be a bad oil pump rebuild using one of the POS kits sold by a lot of suppliers that should know better. Was the oil pump overhauled?

Dan
 

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