Main/Rod Bearing Replacement

Tue Mar 01, 2005 2:53 pm


I am starting to save my pennies to have the main and rod bearings replaced in my Cub. I am hoping that this will at least partially cure my marginal oil pressure issue. If it doesn't, then I guess that I will run it until it quits because I can't afford a complete engine rebuild.

My issue: My Cub shows oil pressure just above the red on a new OEM gauge at operating temperature and speed. It shows about 20 psi on a generic gauge of unknown origin at operating temperature. It shows good oil pressure on the oil gauge from my Model B A-C. So either I have an oil pressure problem or maybe I don't. Either way, I am going to throw for new bearings hoping that it helps if I do have a problem and can't hurt if I don't. The mechanic is going to Plastigauge and mike the crank before replacing to make sure that it will work since I can't afford to have the crank pulled and turned.

My questions:

1. How much can I expect to pay from the IH dealer for a new set of crank and main bearings?

2. Does the thrust bearings come as part of the main bearing set?

3. What else should I have the mechanic look for while he has the pan off? He is going to clean the pick-up and pan.

Thanks for any advice.

Oil Pressure

Tue Mar 01, 2005 3:15 pm

My guess is that the gauge is the problem.

If you have good oil pressure on two other gagues, I don't think you have an oil pressure problem. I'm not familiar with the amount of oil pressure for the Cub. But, I have several old Allis Chalmers tractors and normal oil pressure, at normal operating temperature, is around 15 pounds.

Tue Mar 01, 2005 3:20 pm

Rod bearings will cost about $8.00 each.
Front and rear crank bearings...about $11.00 each.
Center crank bearing...about $50.00

All of the above are ordered separate if ordered from a delaer.

Not much else to check while the pan is off.

Keep in mind, cubs don't generate high oil pressure.

Tue Mar 01, 2005 3:27 pm

Try the gauges on your AC. Looks to me that it is gauge problem from what you tell us. If that is the case hold on to your pennies for another day, I test my gauges wiht an old freon tank. I bought a kit to convert it into a tank to carry air for a tire into the field so I don't have to ride home on a flat.
The kit has an air gauge in it and I substite my question gauge for it, I fill the tank to 30 lb of pressure and expect my questionable gauge to read 30 lb. I use a regular tire gauge to verify pressure in the tank.


Tue Mar 01, 2005 4:39 pm


:P I just replaced my main bearings using the nail trick somebody posted it worked a lot easier than I thought it would. In the manul they list slightly oversized bearings I do not know if they still offer these because I had already ordered bearing before I found out about them. :oops: My thrust was wore lot more than the bearings the crank would move back and fourth about a 1/4 inch now it is under 1/8 inch. My oil pressure was good at an idle cold or above 1/2 throttle but when warm at idle I lost it. :roll:

Tue Mar 01, 2005 8:16 pm

That's called "end clearance" on your main.It should be .004 to .008 in a perfect world. Side to side play.My cubs was like yours.The crank takes a beating there(center main).Had to beef up the area on my cub's journal.
Rick with the pan off just check the end clearance. After all I don't think it really matters,This is not a race engine and were not redline it @7800.Just make sure its not that bad."k" :wink: Oh yes cub's oil pressure should be 30psi.per I look ,"bend down and get a kink in my neck"at the hash marks and count 5 , 10 , 15 , 20 , close to 45 ah its good.If i lost oil pressure my caution panel light will illuminate. :lol:

Tue Mar 01, 2005 8:32 pm

One thing I think you should also check is the oil Pressure valve and spring on the right side of your block just under your ignition (think that is where it is). My valve was stuck. I finally got it out and sprayed it with brake cleaner and used a 20 gauge brass brush and give her a good bushing. I think that this should help your pressure come up too.

Tue Mar 01, 2005 10:15 pm

Boy am i embarrassed that I didn't mention the relief valve.


Wed Mar 02, 2005 10:46 am

Hey RedNed

8) Thanks I am not doing a rebuild now. What I have is a Snow-Ball project. It started with just replaceing a head gasket. The radiator was bubbling inside and their was some oil in it too. The local IH dealer had head gasket in stock it was saturday and I wanted to get it DONE. Whoever had it apart before did'nt use thread sealer on the bolts and I almost did'nt get three out. Had the head off and said to myself self I'm this far I better lap the valves. The '64 had been in a barn fire then sat outside at least two years before I found it and swapped a horse I didn't like for it. Got the valves done got. :cry: Well ya know it had a lot of blow by better check the rings maby ones broke nope but the end gap was .043-.065 and it should be .007-.017. Ok so new rings and rod bearings. Man I'll be mad at my self if I don't do the mains. Its kinda hard getting under the there with mower on and those last three oil pan bolt in the bell housing made me get a 1\4" drive swivel socket to get them. but the engine is back together now.
:roll: Now I'm looking at finding a crank pully to replace the one on it which was broken and badly welded up. :oops: Probally end up having to pull the front end off to do that :?: Wonder what is next :arrow: :arrow: :arrow:

Waiting for cub #2 before doing a real rebuild just paching for now.

:wink: Amazing all the carb threads just when I have mine on the table ready to do :!:

Wed Mar 02, 2005 12:52 pm

Thanks, guys for all of the information. I will try testing the gauges first since they all read differently. Then I will try cleaning the relief valve. Then proceed to the bearings if necessary.

Will keep you advised of what I find.

Wed Mar 02, 2005 5:08 pm

Cowboy, if you have oil in your coolant, it is not coming from a bad head gasket. There are no oil passages coing up to it.

Rick, It sounds as if you may have a bad guage, but you should remeber tha on an old IH engien, 20 pounds if plenty of oil pressure when hot. alos do NOT run it until it quits due to low oil pressure. Instead of grinding crnakshaft and installing new bearings, there is a good possibility you will have to replace it and possible a rod or two also. Pay some now or pay a lot more later.