Farmall Cub

RECENTLY DID COMPLET ENGINE OVERHAUL ON 1949 CUB. NOW OIL PRESSURE IS GOOD WHEN FIRST STARTED BUT DROPS TO ALMOST NOTHING AFTER IT WARMS UP. ANY SUGESTIONS???? THANKS J. HAYES.

Was any attention given to the oil pump

Did you check the oil pressure regulating valve

What kind of oil are you using

Was the crank turned and/or the main bearings replaced

It is normal for the pressure to fall once the tractor has warmed up. The engine doesn't require much oil pressure.

My '49 starts out at approx. 35lbs. on the gauge, or the midway point, and drops to about 17lbs. after she's good and warmed up. Please tell me this is enough! I too re-did my engine, with new bearings, rings etc...the bearing clearance was .006 instead of the required .002 to .003, but I figured it was way better than the bearings that were in there when I got it. I ran mine all winter pushing lots of snow, and no problems so far. The '49 is my first Cub, I hope to find another good engine some day and put it in. But for now, it seems good.

Who has oil pressure that stays "up there", and how much pressure is it, after she warms up? Looking for some numbers here.

EZ, that's good oil pressure for the older IHs. Many of them idling when hot ran about 4 or 5 pounds of pressure.

EZ:

I don't have a graduated oil pressure guage on Ellie-Mae, just the one with the white and red strip. When I start her up - the oil pressure pops up to about centre on the guage and then stays there. After about five minutes or so, there is a slight decrease in pressure, but negligable as it does not go down to even 1/4 on the guage.

Seems good to me although I do not have a compression tester so I haven't got a clue as to what the numbers are for each cylinder.

I posted a similar message a few months ago. I put 20W-50 Full Synthetic oil in my '50. The oil pressure starts out about 35 pounds and drops to about 18 - 20 pounds when it warms up at mowing RPM. It has never knocked so I am going to let 'er ride until it blows up or I can't stand the noise of her knocking.

The puzzling thing is that even at idle the pressure gauge reads 10 pounds, so I am not really convinced that my oil pressure is what the gauge reads. This is a replacement gauge of unknown quality installed by the PO.

If your engine doesn't knock, I would recommend installing synthetic oil since I am told that it doesn't lose viscosity as much as petroleum when it warms up. Even at $4.00/quart, it's cheap insurance.

Synthetic oil did keep my oil presure higher when HOT

It is probabley the clearances on the crankshaft bearings. .oo6 is way too much. when the clearances are right on there should be slightley less the .001 clearance. never more than .002. all my cub engines after a proper rebuild hold 30lbs hot at high idle. at low idle the keep around 22-23. I would say as long as it doesnt have a high RPM knock then your ok. If it were me I would go to a higher voscosity oil. straight wt is better tham multi weight. I would go with 50 wt in the summer. and 20 in the winter till you can have the crankshaft reground and new bearings installed.Hope this helps

TX ALL REPLIES----OIL PUMP WAS REPLACED, AS WAS REGULATOR VALVE AND SPRING. CRANK WAS CHECKED BUT NOT REPLACED. TRIED 30 AND 40 W. OIL.

I agree six is way to much I never even set up raceing motors with more than three also need tourque spects on cub head rods and mains please help this is really great site

Tractortommy:

Click on the Manual Server link below . Under the Blue Ribbon Service Manual you will find The GSS-1411 Service Manual. In Section 1 - Engine you will find all you need to know.

have fun on the rebuild

Thanks for the info this will help a lot I noticed when taking the fan apart that it contains oil is this also a way to oil dampen the engin as it dose not have a vibration dapner my motor looks real good inside but will freshen it any way also waiting for a glass bead machine so i can clean and paint t he parts not going to be a trailer queen just nice and clean

the oil in the fan lubricates the fan bearing. there is a standpipe inside that allows for the correct amount of oil to remain when the fill hole is rotated to the down position. simply add some oil and rotate the unit 180 to drain the excess.

artc wrote:the oil in the fan lubricates the fan bearing. there is a standpipe inside that allows for the correct amount of oil to remain when the fill hole is rotated to the down position. simply add some oil and rotate the unit 180 to drain the excess.

Leave the filler turned to the bottom for a little while before you put the screw back in. If you don't it sure makes a mess. Guess how I know.