2n low oil pressure, the saga continues

For comparison, my 8N was rebuilt several years ago and I get 50 PSI cold, 30 hot at mid throttle and 25 hot at idle using 10-30 oil. Those measurments are with the original gauge, maybe my gauge is the bad one.

Keep in mind the cam is going to be an oil loss area.

What oil were you running for this test? 30w or 10w30? I'd try 40w or 20w50 ( 15w40 ) and check it again.. perhaps even stretch that spring and see what effect it had. Still.. like I said.. that is an acceptable operating pressure range.

Soundguy

When you drop the pan.. try 20w50 oil.

( though hard to beat a good 40w ).

Still.. 5-10 psi hot idle is acceptable.. though I know you are disapointed at the rebuild numbers.

Throw in your old oil pressure spring and stretch it.. though that is a long shot. I'm sure we know that the cam clearances are where your oil is going.

My 8n is 40 cold 20 hot.. the NAA starts at almost 50 and levels off to 30 hot.

My 2n is 18-20 cold.. 8-10 hot all on 30w oil. The JD 'B' runs in the 'medium' like it is sopposed to in the book, hot or cold, and my IH cub runs at about half way on the gauge cold, and about 1/4 of the way on the gauge hot. manual says it needs 1/8 of gauge hot minmum.. so that is good to go.

Good luck

Soundguy

If you did have the block knurled all you would be accomplishing is to speed the wear of the cam beaing surfaces since it would rapidly wear down the high places created by the knurling and knurling takes material away from the bearing surface that can't be replaced when it is knurled.

It also would not have any effect on encreasing the oil pressure since when it is knurled it would not prevent or change any flow of oil over the beaing surface as the oil will still have the same clearance to move through when it is knurled as it moves around the high places created by the knurling.

Don't!

Zane

It would probably be a good idea to start with a new cam along with the bearings.

That being said, you would probably be exceeding the cost of a good used replacement block!

I really doubt that the low oil pressure is caused only by the cam bearings, unless they are REALLY worn badly.

What is the condition of the oil pump? Wear here is critical.

New oil pumps are available with either 9/16" wide gears or the 3/4" wide gears that were used on the later 'N tractors.

The problem is that the main bearing bores have to be align bored when a new pump is installed, as it is part of the front main bearing cap.

If the old oil pump is worn at all, a new one will go a long way towards restoring oil pressure.

Yes, it is a known fact that you need to align bore the mains when replacing the oil pump, just as you do with any engine, when replacing a rod or main bearing cap.

Just because he has "rebuilt" the oil pump, it is not necessarily good. The rebuild kits contain the shaft and gears and bushing, but do nothing to address the wear caused to the pump housing by the gears. As the bushing wears, and the shaft moves a bit off center, the gears wear into the pump housing. When a new shaft and gears are installed, (if there has been excessive wear to the case) there will still be internal leakage in the pump, worse when the oil is warm, due to the excessive clearance between the gears and the pump housing.

I certainly cannot confirm or deny the condition of his camshaft and bearing bores from a distance, but as I posted before, unless the wear is considerable, I'll bet there are other contributing factors, such as a weak oil pump. I would check the camshaft jornal diameters, also. If the cam has considerable wear, replacing it would tighten things up a bit.

As far as the filter restriction, we have discussed that here before. The oil enters the filter canister from the side, passes inward to the center of the filter, and enters a tiny hole in the side of the center tube of the filter near the top (to allow air that rises to the top to purge). The tiny hole in the side of the center tube acts as a restrictor. The oil then flows downward, through the hollow center tube, and out the bottom, where it is piped to the governor. (Or back to the crankcase, on older models.) No restrictor should be needed at the governer.

There have been questions, however, if any of the filter canisters had a restriction at the inlet fitting also. I cannot answer that with certainty.

If you'd like more info on new pumps and the need to align bore, email me.