Rear Main Babbet Melting

[29FordRoadster]

Good Morning Friends, I have a problem with my 29 Roadster. The rear main bearing was leaking oil very badly. We removed the motor and took out shims to get proper clearance in the main bearings. We overhauled the transmission and replaced all bearings, shafts, and used a good used original cluster gear. We replaced the pilot bearing and spring, also we installed a lightened flywheel and V/8 clutch and pressure plalte. Now here is the problem. The motor leaked oil worse after all this than it did prior to the work we did. We removed the pan and the rear main. The thrust on the rear main bearing was so great it melted the babbit to the point it had filled the return drain hole. Lack of oil was not the problem as it was leaking two quarts about every 100 or so miles. Do any of you gentlemen have any ideas what may have caused this problem? Any ideas will be greatly appreciated. I will inform the board if and when the problem is resolved. Thank you very much. Wayne R.

 

[Jim Brierley]

Perhaps there was no clutch free-play??? This would put constant pressure on the thrust.

 

[Kohnke Rebabbitting]

Good Morning Friends, I have a problem with my 29 Roadster. The rear main bearing was leaking oil very badly. We removed the motor and took out shims to get proper clearance in the main bearings. We overhauled the transmission and replaced all bearings, shafts, and used a good used original cluster gear. We replaced the pilot bearing and spring, also we installed a lightened flywheel and V/8 clutch and pressure plalte. Now here is the problem. The motor leaked oil worse after all this than it did prior to the work we did. We removed the pan and the rear main. The thrust on the rear main bearing was so great it melted the babbit to the point it had filled the return drain hole. Lack of oil was not the problem as it was leaking two quarts about every 100 or so miles. Do any of you gentlemen have any ideas what may have caused this problem? Any ideas will be greatly appreciated. I will inform the board if and when the problem is resolved. Thank you very much. Wayne R.

Pictures would maybe help. There is a list of things that could have been at fault. What was the end play, how old the babbitt, what did you use for shaft clearance, did you check the flywheel housing for level with the crank flange. Did you pull the rear main plug in the cap, and check for obstructions, in pipe, and cap. just blowing air through it will tell you nothing. Did you check the oil tube in the block for obstructions, did you re-adjust the front and center bearing. Babbitt will only melt from heat if something did not have the clearance for oil. If you only adjust the rear main, and not take up a sloppy center, and, or front, that will through a bind on a tight rear main.

Thanks Wayne, Herm.

 

[29FordRoadster]

Pictures would maybe help. There is a list of things that could have been at fault. What was the end play, how old the babbitt, what did you use for shaft clearance, did you check the flywheel housing for level with the crank flange. Did you pull the rear main plug in the cap, and check for obstructions, in pipe, and cap. just blowing air through it will tell you nothing. Did you check the oil tube in the block for obstructions, did you re-adjust the front and center bearing. Babbitt will only melt from heat if something did not have the clearance for oil. If you only adjust the rear main, and not take up a sloppy center, and, or front, that will through a bind on a tight rear main.

Thanks Wayne, Herm.

Thanks JIm and Herm for the replys. Herm we did check all the main bearings for proper clearance using plastigage method. We did pull the plug on the rear of main bearing and used a proper sized drill bit to slowly remove a small amount of babbit that had gotten in that tube. The main return tube was clear. The engine was rebuilt in 2010 so the babbit has been about two years since it was poured. There was about 40 thousandths of end play in the crank. At this time, I am not certain about the flywheel housing being level with the crank flange. Thanks to you both for the information. It is much appreciated. Wayne R.

 

[Kohnke Rebabbitting]

Thanks JIm and Herm for the replys. Herm we did check all the main bearings for proper clearance using plastigage method. We did pull the plug on the rear of main bearing and used a proper sized drill bit to slowly remove a small amount of babbit that had gotten in that tube. The main return tube was clear. The engine was rebuilt in 2010 so the babbit has been about two years since it was poured. There was about 40 thousandths of end play in the crank. At this time, I am not certain about the flywheel housing being level with the crank flange. Thanks to you both for the information. It is much appreciated. Wayne R.

If there was .040 thousandths end play in the crank when you took it down the first time, that just should not be from wear. There must have been a lot when the babbitt was renewed, and was cut to large, as it is a long way from .003 thousandths. Did you put the cap back with .040 thousandths, or did you try to fix the end play? The problem is the .040 thousandths may be gone, not knowing which end of the thrust? If the missing clearance has allowed the flywheel to go far enough a head, and wear on the back of the rear main cap, it may have generated enough heat to melt the rear thrust babbitt, don't know? Herm.

 

[29FordRoadster]

Thanks for the reply Herm. The .040 thousandths end play in the crank was not there when we took the engine apart the first time. We only discovered it yesterday when we took the pan and main bearing out. We are assuming now that there will be the same wear on the top half of the rear main as there was on the bottom half. We will pull the motor in the next few weeks and may find more answers or problems. Thanks again for the information. Wayne R.