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Discussion Starter · #1 ·
I had a an issue with oil pressure on my 8N tractor lately and was wondering about the strange filter design and also wanted to know how oil pressure is measured on these tractors. I just picked up a new oil filter for my '52 8N and inspected the freshly sand blasted, cleaned and repainted filter housing to make sure passages were clean. It took me about 30 minutes to finally find a tiny hole in the center post. Probably 3/32 inch dia. or smaller. it was totally filled in with gunk which did not come out in the cleaning process. A dental pick finally uncover the hole which I knew must be in there somewhere. I had been expecting a much larger hole. Does this one tiny hole sound like what you out there know to be correct and isn't this a likely trouble spot?


Premium Member
3,693 Posts
First off welcome to the fourm. Have been getting a good size influx of N people comeing over, and that will be good for all of us.

As for the filter. Ya, it is kinda a strange setup by modern standerds, but you have to remember that till probably the early to mid 50's, and lot of cars did not have ANY oil filter yet. Also the filter is not a full flow filter like a modern engine has. As for the hole size. remember those pipes going to the filter is pretty small, not much bigger then break line. Being it is not full flow, it just does not need a bigger line.

I am sure there are others that will jump in with more info for you, but one thing you always have to keep in mind about these tractors......

1 they were built to be inexpencive

2 they were built to be serviced by almost anyone in the feild

3 it has been chugging along for 50 some odd years, so they must have done something right.:D

Premium Member
3,786 Posts
Welcome Dave!!!

The pressure is read off of a tap into the main oil gallerys on car engines, or the 'N engine. In both cases the pressure reading reflects the actual pressure of the oil in the engine oil gallery trying to work it's way past the engine bearings. The only difference is that the full flow of the (modern) car engine passes through the filter before entering the main oil gallery. The pressure measurement point is after the filter, so it is measured in the same relative area as in the 'N engine.

There is a far more elegant reason for the oriface hole in the center tube being near the top. The hole being near the top lets the air pass out of the housing so it can refill with oil after a filter change. Without the hole being near the top, you would have a large air bubble in the filter, and oil would flow through the lower part of the filter only. Good luck finding the gunk and getting it running. What is your oil pressure running at?

Other than that, be sure to post some pics soon. What filter are you using? Fram, NAPA??? Here is a list I compiled a while back for all of the oil filters you can use on a 8N: (I personally use the Napa Gold 1010)

Baldwin P40Big A 92010
Bosch 72127
Carquest 85010
Fleetguard LF574
Ford CPN 6731B 9N-18649, 9N-6714, 9N-2731
Fram C-3 C-3P
Hastings Mighty M3LF-130
Luber-Finer P3
Motorcraft FL144
NAPA Gold 1010
Purolater L 20110, L20701
Texaco HSO 100
P 70 FR
Unocal 76 OF 1010
White 10575
Wix 51010
Fleetrite LFR-8574

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