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Ford NH 1920 Oil pressure problem

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Sean Abbott
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Posts: 1
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2005-08-14          114852

Bought a basketcase 1920 with a spun bearing. Overhauled the engine-- turned the crank; mains + rods, bored the cylinders. Checked all the clearances on all the new rod and main bearings. Checked the clearences in the oil pump, they were within specs by a little but within none the less. My problem is this; when I first start the tractor there is NO oil pressure. Depending on outside temperature, the oil pressure stays at zero for 8 to 30 seconds, 70 to 5 degrees respectively. After this period the oil pressure jumps right to 45 lbs and stays there no matter how hot or cold or what RPM. After sitting for 8 hours, when started, oil pressure builds immediatey, drops to zero for a second or two then goes to 45 lbs. After 24 hours the drop to zero lasts 2-3 seconds. I took the oil filter off after the tractor had sat unused for a week and there was no oil in it. It appears that the pressure side of the oil gallery is draining back to the pan and upon restart, the pump has to prime itself, then fill the gallery and filter before it can build pressure. I dropped the pan today thinking I may have left out the o-ring on the suction line, but it was in place. I am running Delvac 15w-40, NH oil filter (the new all metal small housing ones). I've checked the oil pressure relief valve,it is fine. Changed the oil pressure sending unit, added a mechanical oil pressure gauge teed off of the sending unit, tried a NAPA oil filter with a much larger canister and paper element(It increased no pressure duration)
Other than this, the tractor runs fine. What is normal for a 1987 Ford/NH 1920 as far a oil pressure after start up is concerned? Local 2120 and 2110 tractors with a gear pump have no objectionable oil pressure issues.

Thanks in advance for any help.
Sean Abbott seanofmaine hotmail.com


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Ford NH 1920 Oil pressure problem

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jhaems
Join Date: May 2007
Posts: 9 Minneapolis, MN
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2007-05-07          141903

Trade you for my problem. We just rebuilt a 1710 and I can't get the oil pressure over 27psi. We also have checked everything 3 times.

For what it is worth... the operating spec for the 1710 is 37-57psi.

I was fascinated that the oil filter wasn't getting oil... I'm going to check that out again.

About 10-12 years ago I ordered the service manual for the tractor from somewhere... I assume it was a FORD/New Holland dealer. My mechanic said it was one of the best he has ever seen.

Good luck. ....

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Ford NH 1920 Oil pressure problem

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randywatson
Join Date: Apr 2007
Posts: 109 texas
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2007-05-08          141924

Sean, you might try a filter with an anti drainback valve, or a filter with a better qual valve if the one you are using has one.

that might solve the temporary no pressure on startup, as you discovered the oil draining from the filter during down times causes the pump to have to push the oil back up from the oil pump through the filter, into the engine to start building pressure.

another thought, is the filter is going into bypass mode till the oil warms up, not sure exactly what effect that would have on pressure, but could cause what you are seeing. ....

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Ford NH 1920 Oil pressure problem

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hardwood
Join Date: Dec 2002
Posts: 3583 iowa
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2007-05-08          141926

Sean; In your first sentence you say "Spun Bearing", this has me wondering if a faulty oli pump wasn't the cause of the needed overhaul. Your satement that after a startup the pressure comes right up then drops to zero for a second or two then goes back to normal highly indicates there is an air leak that breaks the suction between the float screen and the actual gears of the pump. Your problem is not consistent with oil escape after it leaves the gears of the oil pump. Something is wrong that breaks the suction, perhaps when the float drops a bit going to the oil level you get the momentary drop because something opens an air gap for a bit, or maybe the float hesitates a bit before droping to the oil level. Take the pump off get a rebuilt one, I think your mystery will be solved. just a side note which would have no bearing on your present problem. did you replace the camshaft bearings, they are often overlooked and can be a big contributor ot low oil pressure at warm operating temps. Best of luck. Frank. ....

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Ford NH 1920 Oil pressure problem

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clayg100
Join Date: Jun 2011
Posts: 2 dubois
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2011-06-21          179105

i got a cm274 mower same engine with oil pressure probelm. On the rocker shaft between one and two cylinder these a philip head screw that keeps the shaft inline so oil doesnt comes out. when loss or broke oil leaks out and losses oil pressure. Spent $350 to fix it and all it was, was that little screw. hope this helps ya. clay ....

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