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i have a 1947 2n that has about 40 pounds of oil pressure cold idling but after you work her hard and heat her up to operating temp she only shows 5 to 10 pounds of pressure. i put a new gauge on it too. will she be alright? she gets up near 20 if you rev her up some. thanks,
chuck d
 

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seems about normal for an old, maybe a little tired N. Mine runs 40 cold, and goes down to a bit under 20 warm. There is a bypass spring in the oil system that can be adjusted, I have never done it, so maybe someone else has done it, and can give some better idea on how to do it
 

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Yep these Ns will run on nearly no pressure. 1Do you know what wt engine oil is in the crankcase? Did you try changing to a heavier wt oil to bring up your oil pressure? Did you consider that your oil pressure gauge might have lost its calibration? How is your compression and do you burn any oil or smoke currently?

You can buy a lot of oil for price of overhaul. How is engine performance? Dod you have enough power to do the job? Climb the hill, pull the plow? Does the engine start easily?

Let me know and I will try to help you further. Best of luck.
:tractorsm
 

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Discussion Starter #4
the oil pressure gauge is brand new. i am running straight 30 wt. oil. i have heard that 50 wt. oil will raise the oil pressure. is this correct? the engine starts fast and doesn't smoke any or burn any oil and has plenty of power. i will probably try the 50 wt. oil before i do anything else. i have heard the oil pressure relief valve can cause you not to have good oil pressure too. but since it takes it a long time to lose pressure i don't really think this is what it is. thanks,

chuck d
 

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The loss of oil pressure when the engine is warmed up is generally caused by worn crankshaft bearings. When the engine is cold the oil will be harder to push through the system, but as the engine warms up the & oil becomes thinner the area between the crankshaft and the rod & main bearings which is larger because of wear will allow the oil to flow with less resistance causing the lower oil pressure. You can add an oil treatment like Lucas Oil Treatment to the oil to make it thicker, but the only sure way to correct the problem is to regrind the crankshaft, rebuild the oil pump, & install new lower bearings. This can get into your pocket book pretty fast, so you might want to consider the oil treatment. Hope this is of some help. Frank at Holz Equipment Ser
 

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I've got the opposite pressure........My 50lb oil guage pegs out at startup then seems to drop to maybe 40lbs. I was thinking maybe I've got a pressure valve problem. I picked up a new spring this week just in case. I'll be using the tractor this weekend and don't want any of those weird problem.

T
 

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oil pressure

T
I'm with you. After 10 years in a field, I've just started thru my 8N. new wiring , clean carb new rad, new oil pres. gage. when started gage quickly goes to 60 or so --may be pegged and stays there.

I t barely runs on one lung with only 35 psi in #2 and 0 to 5 psi compression in the other 3. Wet testing with all plugs out takes #2 to 70psi and barely affects the others. amazing it let me drive it around for a couple of miles.

What is the cause of the high oil pressure that T and I have?

Are there places on the forum I should be looking for "low compression overhaul tips"? I'm brand new to the forum

Springsrick
 

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Could it be an oversized Pressure relief valve Spring?

I was just reading another post I'd stashed for reference, and it said there was a common but misguided practice of putting in oversized spring on the oil Pressure Relief Valve in a misguided attempt to raise oil pressure readings when the oil is hot. (Sorry, I lost the Authors name).

Could be worth checking it out. See the shop manual Fig. F026 for spring location. Good luck!

SpringsRick
 

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that high of OP would be the falt of the spring. Maybe someone shimmed it up a bit, or streched it to up the PSI a bit. I would get in there and check it.


One thing you HAVE to say about these N's. No matter what, they just keep ticking. 2cyls, one cyl, does not matter, they STILL run. My 8N runs good, and has OK power, but mines a smoker. Will use about a qt ever 2 hours of run time. Looks like we are in need of a big TF N motor rebuilding party.:D :partydanc
 

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Hey,
Update on my pressure.............I did replace my oil pressure relief valve spring. Come to find out to compensate for what I guess was a bad oil pressure guage the spring had been stretched. The spring should stick past the plunger alittle less than 3/4". Mine was over 11/2". I've got 40lb OP now at startup with the new part!!!

Thomas
 

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Good call and replacement! Sometimes people just don't get it.
If you are going to replace parts on anything much less a 50yr old piece of machinery, stay to original spec and try to use NOS if possible. Like Paul said, they are built like tanks and run, run, run so why would you like to monkey around with good ole-fashioned
stout mechanical design?

Glad you got it working.
:)
Andy
 
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