Oil Pressure good until engine warms up

[CubFan]

I have a 48 Cub that has been almost fully restored; 6volt system gone; and the engine does not use any oil. When starting, oil pressure is almost 50lbs when cold but 15 minutes into mowing work it will barely register on gage at idle, maybe 10lbs at full throttle. I have shimmed the Bypass Spring an 1/8th of an inch and found it was already shimmed a 16th or so and this seems to be all the difference that can be made here. I have not yet checked to see if new crank and rod bearings were put in but has anyone heard that the block can be wore out because the camshaft does not ride in bearings???? CubFan.

[Bigdog]

Have you verified the accuracy of the oil pressure gauge? Your pressure swing may not be as severe as you think.

[CubFan]

No I have'nt, but will check it out. Thanks.....

[Ron L]

CubFan. Another thing to consider.... I don't know of a Cub yet that doesn't drop in oil pressure after it warms up real good. Just have to watch how low it drops. Just do as Bigdog says and check your warmed up pressure.

[Maritimer]

Cub Fan,
I have had the same problem as you have, so I did the pressure valve thing and checked the rod an main bearings, they were wore as well as the crank was wore. I had the crank ground and fitted with new 20 thou bearings. I haven't started it yet because I am replacing all the gaskets and seals while putting it back together and only have a limited time to work on it.....cause the wife say's I have to spend quality time with her. No comments from the peanut gallery Tonite I just put the new oil seal for the govenor and put it together....I was just going to put the front end back on when the CALL came for me to come in the house. Do you guy's have this problem? I figured that I may as well go in and put our child to bed before I get devorced(sp)I'll get the friggin thing together yet!!!

[Charles (49) Mo]

We use straight 30wt oil.

[CubFan]

Yes, I watch the gage like a Hawk and do'nt let it idle when hot. Am going to borrow a test gage and see if their is any difference like yall suggested. Maritimer,, I know just where you're comeing from! You have to be careful how much time AND money you spent on projects like ours!
I have been using straight 30 wt oil and have considered 40wt. Afraid to go to thick though. I would'nt be surprised if it needs crank bearings and if it do'nt get worse Ill wait until next winter to check lower end. Wife watches our money kinda close you know.
We apreciate the responces Guys!!

[beaconlight]

Take her to see new lawn tractors. The prices are about international telephone numbers. She might loosen up on the purse strings, or decide to do the grass with pinking shears.
On my 37 plymouth we used 50 weight oil. It ran for a couple of years like that and I sold it in 1955. The other guy got a couple of years out of it too. We were young and never had enough for gas, never mind fix something till it absolute broke.

Bill

['Country' Elliott]

CubFan...My 1948 Cub's oil pressure guage reads all the way on HIGH when started up and when still cold . When she warms up and under a load, she reads dead-stick in the middle of the pressure guage .

['Country' Elliott]

CubFan...You might want to try adding some LUCAS oil additive to your 30 weight first . Run her awhile and see if the pressure comes up . Sometimes low oil pressure relates to passages being blocked or clogged from non-use . Don't be afraid to run her...drain the oil, change the filter and run her some more till you get all the old crud out !

[beaconlight]

'Country' Elliott Would it help him with some possum grease in the oil??????

Bill

['Country' Elliott]

Hey Bill...Why sur nuff !!! Possum grease (when you're in a pinch) is darn near as good as LUCAS !!! It's a shame tha po ol' possum don't realize that he could just SLIDE across most roadways...instead a tryin' to run !!!

[CubFan]

Yes, my neighbor has two Lawn Tractors and is running them almost everyday and wearing them out. Those little air cooled engines are not cheap! He had a Ford 8N and sold it...
Trying a good additive like Lucas might buy me some time,will check into it.
Not a bad concept!! Possum grease for lubricant and Possum Belly for supper!! There are still bargains in this world!!.... Thanks guys......