I purchased an 8N a few months ago that had sat for a few years and just got it into my shop. It runs good with no knocks in the engine but shows no oil pressure on a new gauge. I have loosened the line going to the gauge and no oil comes out when running. I have only had it running for short periods as hopefully not to harm anything. Is there a way to prime the oil pump?
- Thread starter T L
- Start date
yep, u can remove the 15/16" plug on the timing cover, remove the spring and plunger, and put several ounces of oil (i used 90W) thru the inner hole that the plunger seats into. then close it up and fire it up, u should have pressure at this point.
or, some folks like to use a garden sprayer hooked up to one of the external oil lines.
TL,Just take that line loose from the gauge and hook a oil pump can,ketchup bottle full of motor oil or garden sprayer with a piece of vacume hose.Put about 2 cans/bottles of oil in there,hook the line back up and start it up,then watch for oil pressure as soon as it starts up.If not shut it down and replete.Putting oil in there fills the oil galleys,pump and oils the crankshaft.Plus it is much easier than the plug at the front of the engine.
Mike Groom
Well-known Member
If it runs with no knocks you may have a plugged oil line to the gauge,I would take the line off and start it up to see if you have oil to that point where it comes out of the block.
He dosen't need to start it again until he has primed the oil pump and has oil pressure when cranking it over with ignition switch off.If it is run any more with out oil pressure he is likely to need a new crankshaft and rods,and maybe the block align bored.depending what bearings it wipes out.It could be to late already,depends how long and how many times it has run without oil pressure.
TheOldHokie
Well-known Member
- Location
- Myersville, MD
Now the interesting part - wait and see if it maintains prime or you get a of the loss of prime after it sits awhile.....
TOH
Tom Massachusetts
Member
I bought my 8N from a guy that just rebuilt the engine. He would lose prime every day and gave up. First I welded a 9/16 nut to the 15/16 nut and it was much easier to get off with the small wrench. I then pulled the pan and took out the pump that he put in. The gears measured about .020 shorter than they should be. I bought a pump kit from Just 8N "Tisco". and the gears were right. Put it back and no problems. Nice engine with good oil pressure cheap.
Tom Massachusetts
Member
Could be that he got a defective oil pump kit made by "Atlantic" the gears are about .020" short and the prime just runs back to the pan.
Late to the post , I had an old N that I wanted to run till the end of the mowing season before tearing it down , It would lose prime after a few days of sitting . I installed an screw in valve stem to the bottom of the oil canister . A short blast of air would back flow enough oil to prime the pump . I also found that parking it nose down on a step hill helped the time from 0 psi to "I got something" psi . I planned a rebuild and was not worried about low oil pressure but not too happy about dry starts .
I have also removed the oil plug and slipped a piece of hose over the end of the pick up tube ( which is about 1/2" OD ) then held the hose with a big funnel stuck in the other end , above the hood while pouring oil in the funnel , then hit the starter . You can pour faster than the pump will suck at low idle . After 1/2 a quart I turned the key off and reinstalled the plug / screen and added fresh oil .
TheOldHokie
Well-known Member
- Location
- Myersville, MD
My experience is more like .010/.012 short on the wide gears and about half that on the narrow gears. I don't think that causes the prime to "run back to the pan" anymore than with good gears. If you look at the pump I think you will see that the oil needed to self prime is held in a low spot in the housing below the level of the oil inlet.. My analysis is that with the overly wide end clearance the pump bypasses excessively and can't generate the suction needed to prime itself with the relatively small volume of reserve oil normally held in the pump. They also don't produce full volume/pressure once primed.
TOH
Tom Massachusetts
Member
I bought my tractor from a guy that just spent a lot of money on a engine rebuild only to lose prime every day. I had the pump out 3 times trying to fix it before finding the gear problem. Bought a Tisco kit and the gears measured right, fixed the problem. Now holds prime for weeks.
Good tractor bought right.
Now to fix the lift problem.
Good tractor bought right.
Now to fix the lift problem.
TheOldHokie
Well-known Member
- Location
- Myersville, MD
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