new model A owner, modification questions

[bdave_mcc]

Originally Posted by darrylkmc

bdave_mcc,

To me, it looks as if your photo your Rear Main Babbitt is cracked.

Look at the right side, front side of cap, at the radius where it is flush with the block, both sides appear separated. It looks as if it runs from one side to the other, not parallel but at a arc, looks like pitting at the bottom.

Darryl in Fairbanks

Yes it is cracked. I was wondering what problems , if any that will cause. I found the return tube missing, too much crank end play, and the broken bearing. The engine looks pretty fresh from what I can tell. All the babbit looks OK except for the rear cap and it appears to have all new sleeves and pistons.

[darrylkmc]

bdave_mcc,

I would pull the engine, remove the crankshaft and examine all of the bearings.

If your problem is isolated to only the rear main cap, there are people on this forum who have had success with having just the rear main poured and line-bored. I have no personal experience with this procedure.

A rear main crack at the babbitt like yours shows has likely separated from the cap itself. This will cause oil to flow under the babbitt and and out the rear, bypassing the slinger and/or seal.

Darryl in Fairbanks