Oil Pressure After Rebuild Issue

I had a spare 2N engine I had rebuilt last fall to replace the working engine that was smoking bad ,fowling plugs and low oil pressure. New sleeves, pistons ,rings and valve train has it running great, quiet and starts easy. Oil pump had new gears installed. I plastigage on rod bearing for kicks and it came out at .0015. Machinist said he checked all journal clearances and also camshaft and oil pump bearing. Had all this done for a modest fee and I was glad as the crank did not need reground and rod and main bearings were OK according to machinist. Well, now to the oil pressure. I used Rural King 10w30 for break in and oddly the pressure was super high on cold start ( pegged 50 PSI gauge) but would drop to less than 5PSI when hot Idle. I changed oil to Rotella 15w30 hoping it would help low pressure at idle but it did not help. Looks like I will be pulling this engine again. Again, the engine runs like a well oiled sewing machine and seems odd the pressure drops so much between cold and hot . What is most likely culprit? Spring and plunger on oil relief look OK but has not be en changed and common sense tells me it may cause high oil pressure but not low. Thanks for any suggestions. Bill
 
(quoted from post at 20:55:15 01/28/16) I had a spare 2N engine I had rebuilt last fall to replace the working engine that was smoking bad ,fowling plugs and low oil pressure. New sleeves, pistons ,rings and valve train has it running great, quiet and starts easy. Oil pump had new gears installed. I plastigage on rod bearing for kicks and it came out at .0015. Machinist said he checked all journal clearances and also camshaft and oil pump bearing. Had all this done for a modest fee and I was glad as the crank did not need reground and rod and main bearings were OK according to machinist. Well, now to the oil pressure. I used Rural King 10w30 for break in and oddly the pressure was super high on cold start ( pegged 50 PSI gauge) but would drop to less than 5PSI when hot Idle. I changed oil to Rotella 15w30 hoping it would help low pressure at idle but it did not help. Looks like I will be pulling this engine again. Again, the engine runs like a well oiled sewing machine and seems odd the pressure drops so much between cold and hot . What is most likely culprit? Spring and plunger on oil relief look OK but has not be en changed and common sense tells me it may cause high oil pressure but not low. Thanks for any suggestions. Bill

A good tight flathead engine should produce 30+ PSI at hot idle. Assuming you have reliable readings from a known good gauge most likely culprit is excessive oil clearances somewhere. The drop from 50 PSI cold to near zero when hot is exactly the sort of behavior excessive oil clearances will produce. There are only a few places to look on a flathead - oil pump, mains, rods, and camshaft.

TOH
 
Seems strange that mechanic/machinist missed bad clearances. He is retired from his regular job but has done older car and tractor engine work for a long time and seems very knowledgeable and thorough. Oh well, guess I will be pulling it out and apart. I read somewhere that a pump up garden sprayer (with oil) can be hooked up to oil line , pressurized and see where oil is bleeding the most (with pan removed). Will this work? I may try this before it goes back.
 
Before you tear it down wait for a few more replys. Make sure the line to the gauge and the gauge itself is not plugged. Make sure the gauge itself is not faulty.
 
Make sure gauge is good.

I would also wait for more comments, could be an oil filter or missing plug issue.
 
Sounds like excessive clearance in the oil pump.

Very common on N engines, and not corrected by replacing the oil pump gears. Indeed, replacing the OEM gears with aftermarket parts may well increase clearances.

Dean
 
(quoted from post at 22:55:28 01/28/16) Make sure gauge is good.

I would also wait for more comments, could be an oil filter or missing plug issue.
lease explain how the oil filter will reduce N engine oil pressure.
 
(quoted from post at 21:54:40 01/28/16) Seems strange that mechanic/machinist missed bad clearances. He is retired from his regular job but has done older car and tractor engine work for a long time and seems very knowledgeable and thorough. Oh well, guess I will be pulling it out and apart. I read somewhere that a pump up garden sprayer (with oil) can be hooked up to oil line , pressurized and see where oil is bleeding the most (with pan removed). Will this work? I may try this before it goes back.

[i:0d73f0c45b][u:0d73f0c45b]Assuming you have reliable pressure readings[/u:0d73f0c45b][/i:0d73f0c45b] the pressure is going somewhere so your mechanic/machinist missed something. Check for missing plugs or obvious leaks. I am suspicious of the fact that no work was done to any of the bearing clearances and that they all checked out good as new. Assuming they were properly checked and good the 70 year old oil pump would be the next suspect. Since you say he is a "machinist" I will assume the gentleman that did the work knows how to properly rebush the pump and replace the gears. But dropping in new gears isn't going to fix a body that has been worn or damaged by the old one wobbling around for years on end.

Notice there is a lot of "assuming" in the above. If it were my engine I would be double checking ALL of those assumptions myself.

TOH
 
Something similar to that happened to me. There an orifice hole(holes)in the oil filter canister that was plugged.

In trying to remember, located at the bolt stem tube. Size of hole (holes) is 1/16" to 3/32" dia.

Been a long time ago and I cannot remember all the fine details.
 
When I rebuilt my 9n and 8n, I used straight weight SAE 30 non detergent oil. Oil pressure is about 45 cold and about 15-20 hot at idle about 400 rpm. One of my old 8nFord manuals says run the engine at 1500 rpm and the oil should be 25 #.
 
TOH, The bushing in pump was not replaced/Reamed and he said was OK but I wish he would of redone it while it was apart. What plugs are in engine that may be missing? I will replace gauge but pretty sure that is not problem and, provided I have to pull engine and remove pan (pretty sure I will have to); go through clearances. I was going to give him a copy of procedure to rebuild pump off net (I Think you posted it) but didn't as I did not want to insult him, maybe bad decision on my part. I am going to use this tractor for volunter work mowing 4 acres this summer so it will get a working out. Thanks.
 
(quoted from post at 11:10:37 01/29/16) TOH, The bushing in pump was not replaced/Reamed and he said was OK but I wish he would of redone it while it was apart. What plugs are in engine that may be missing? I will replace gauge but pretty sure that is not problem and, provided I have to pull engine and remove pan (pretty sure I will have to); go through clearances. I was going to give him a copy of procedure to rebuild pump off net (I Think you posted it) but didn't as I did not want to insult him, maybe bad decision on my part. I am going to use this tractor for volunter work mowing 4 acres this summer so it will get a working out. Thanks.

The plugs would be the two at the ends of the main oil pipe that runs front to rear in the block but that is not likely to be the culprit. They probably weren't even removed and if they were missing you wouldn't get any oil pressure hot or cold.

I take it the gentleman that did the work is not interested in fixing this for you????

TOH
 
TOH, no I have not even talked to him yet. I wanted to get opinions to make sure I have a educated myself on the matter and possibles of what may be wrong. I'm sure he will cooperate on getting it fixed but I don't want to be BS'ed ,if you know what I mean. Just seems odd that he did not pick up on excessive clearances if journals are the problem so I am suspecting culprit is oil pump.It just means I got to spend some time taking engine out but at least it is clean and degreased and I suspect it will go twice as fast as before I will put a known good gauge on it first. Thanks for help, everyone's knowledge is appreciated.
 

I have battled my fair share of oil pressure issues and have to come up with ways to eliminate before the pump and after the pump and get a idea of pump health... Its not in a book that I know off :(...




I would drain the oil and put a vacuum gauge on the end of the pick up tube and check the ability of the pump to pull a vacuum with the starter only (disable the ignition) , Record it cold...

Add the oil back and run the engine till it was HOT !... drain the oil and recheck pump vacuum (disable the ignition)...


Your cold and hot vacuum should be close if so I would look deeper are above the pump for your issue...

If you try this the end of the pick up tube is 9/16" you will have to adapt it down to fit a vacuum gauge...

I dunno If I caught if the pump gears were changed. Someone made a great post about his issues sometime back and he came up with the replacement gears were not as tall as the originals...
 
(quoted from post at 22:59:37 01/29/16)
I have battled my fair share of oil pressure issues and have to come up with ways to eliminate before the pump and after the pump and get a idea of pump health... Its not in a book that I know off :(...


I dunno If I caught if the pump gears were changed. Someone made a great post about his issues sometime back and he came up with the replacement gears were not as tall as the originals...

He says they were replaced and Steve Dabrowski is the guy reporting the undersize oil pump gears. Personally I've yet to come across any replacement gears that are not the proper width so it's apparently not a common problem. A simple check of end clearance when rebuilding the pump will eliminate any concern in that area. That's something you should be doing in any case since housing wear can increase the clearance.

TOH
 
As TOH noted I found my replacement oil pump gears to be 0.007" shorter than the originals after experiencing the same issues you appear to be having. I put the original gears back in and got a thinner gasket than was in the kit (CNH had the thinner gasket) and this solved the problem completely. I also ordered an additional kit from DC (first was from Just 8N's) and found those gears to also be short the same amount). Check the oil pump to ensure the gear faces are absolutely flush with the front gasket face of the pump. Put a small bit of plasti-gage on the gear faces and put the front on with the gasket and see what the end clearance is. Mine was 0.015" with the rebuild kit gears and after replacing with originals I got it to 0.005" which did the trick.
 
Just a further note in checking the oil pump. You could just drop the pan with the engine in the tractor. Support the transmission with a good stand, Undo the front axle support bolts from the pan and slide the support slightly forward (just to clear the pan so it will drop. Remove the bolts from the pan and from the transmission to pan and you can lower it with a floor jack and get it out. Then you can pull the pump and check clearances. Put a straight edge across the face of the pump and see how much feeler gage will fit between the gear faces and the straight edge. Should not exceed 0.001". The gaskets in my kit were 0.008" compressed while the CNH (New Holland) gasket was 0.005" compressed. A yellow 3M sticky back note is 0.003" thick and would probably work as a thin gasket.

Putting the pan back on calls for cleaning the gasket surfaces and some tear away on the gasket can be repaired using Permatex Best gasket sealer. Then make a couple of dowels to use as guide to align the pan to engine bolt holes. Seals for crankshaft should be ok including a full circle front seal if used. Raise the pan with a floor jack and bolt everything up. Be sure tractor is far enough above the floor so that the pan will clear the oil pick-up when lowered. Might need to drive up on a couple of 2x6 planks under each wheel before supporting the transmission and loosening bolts.

I have done this and it saves removing the hood and removing the wiring etc. But still requires care and patience and a helper makes it easier.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top