Rear Main Bearing

[Fred K-OR]

A friend has a Model A and he found the rear main oil drain pipe was off the bearing. Someone prior to him buying it had apparently "glued" the pipe in the bearing and messed up the hole where it is suppose to screw into.

So the question I have-Could he remove the rear main bearing and exchange it with one that does not have the drain pipe hole all messed up? And could this be done with the engine in the car.

Of course he would have to check the bearing to make sure it fits with his crank using shims.

 

[colin1928]

I personally would repair the thread and fit a new drain pipe
drill it out and rethread it for a insert

 

[BRENT in 10-uh-C]

I agree with Colin, ....repair the cap since the babbitt has been line-bored to this block.

 

[hardtimes]

I personally would repair the thread and fit a new drain pipe
drill it out and rethread it for a insert

Hey colin,
That thread sure is a FINE one,eh ! I think that it is too easy to cross thread with this fine of thread. I did mess up, and just used a tap to clean it out enough to replace pipe...with thread locker.

 

[Fred K-OR]

Thanks guys. I will pass it on to him. I know it is hard to suggest what to do without seeing the problem. The thing that bothered me was it looked like maybe some of the babbitt may be broken along the front edge of the bearing. Anyway will pass the info on to him and he does have another friend that is a welder and maybe can fix this for him.

 

[colin1928]

Rick yes it is a very fine thread and easy to cross thread normally due to the little dob of weld
I am lucky and have the correct tapes for both the 5/16 and 3/8 pipes
Fred forgot to ask is it 5/16 or 3/8 cause if 5/16 early style cap just take it to the 3/8 size I do that on most of my engines if it is 3/8 and the thread is damaged I drill them out tape and install a steel plug that I then drill and tape the plug for the pipe
do not forget to remove the welsh plug and file the pipe removing any ridges after fitting
I think it is always best to the bearing caps and block as a matched set
Colin

 

[Fred K-OR]

Rick yes it is a very fine thread and easy to cross thread normally due to the little dob of weld
I am lucky and have the correct tapes for both the 5/16 and 3/8 pipes
Fred forgot to ask is it 5/16 or 3/8 cause if 5/16 early style cap just take it to the 3/8 size I do that on most of my engines if it is 3/8 and the thread is damaged I drill them out tape and install a steel plug that I then drill and tape the plug for the pipe
do not forget to remove the welsh plug and file the pipe removing any ridges after fitting
I think it is always best to the bearing caps and block as a matched set
Colin

It was hard to tell what size hole was in the bearing because the prior owner had ground out a bigger hole in the bearing. A real messy hole. So maybe the only way to get something back in that hole would be to tig or mig or braze it back into the hole. Any recommendations on which welding method to use? This is assuming the Babbitt is still OK.

 

[Fred K-OR]

TIG it if you can to minimize risk to the babbitt

Thank you for the answer.

 

[hardtimes]

It is also a special thread size. Not 1/8 pipe like some people think. Also it was originally tack welded/brazed in a spot after the pipe was installed.

Thanks for adding that info regarding the weld, as didn't know that Ford had tacked that pipe in. I used 'blue' locktite and am hoping that that will suffice ! Studying the issue, I found out about the two differing sizes, depending on year. Anyway, I got lucky and had the correct tap in my small collection.

 

[Phil Brown]

I just had to fix one like that last month,The cap had a section broken out and missing between the drain pipe and the little plug in the back but with real good looking babbitt.
I took a piece of tubing for the new drain pipe and left a small part of it long to take the place or the old plug on the back side.
Fired up the Tig machine and brazed it in place. The Tig and brazing really helps to keep the heat to a minimum and protect the babbitt but go slow, weld....let it cool....weld..let it cool
If the babbitt is good (and worth saving) it sounds like it can be saved

 

[Marshall57]

I just had to fix one like that last month,The cap had a section broken out and missing between the drain pipe and the little plug in the back but with real good looking babbitt.
I took a piece of tubing for the new drain pipe and left a small part of it long to take the place or the old plug on the back side.
Fired up the Tig machine and brazed it in place. The Tig and brazing really helps to keep the heat to a minimum and protect the babbitt but go slow, weld....let it cool....weld..let it cool
If the babbitt is good (and worth saving) it sounds like it can be saved

I had about the same problem. Looked like someone had set the engine down on the pipe when the oil pan was off and broke it out. There is no pressure on this little pipe and so I just took off the cap and JB welded it in. You would need to make sure that you didn't have it in too far and that the hole is clear. Worked really well.

 

[glenn in camino]

It was hard to tell what size hole was in the bearing because the prior owner had ground out a bigger hole in the bearing. A real messy hole. So maybe the only way to get something back in that hole would be to tig or mig or braze it back into the hole. Any recommendations on which welding method to use? This is assuming the Babbitt is still OK.

I'd be afraid of welding it and heating up the babbit. JB Weld should work fine.

 

[Kohnke Rebabbitting]

They are easy to fix with no problem of heating the babbitt.

We use a wire welder with soft wire.

Cover babbitt with a damp rag, so sparks never touch the babbitt, as it will embed easy.


Tack the tube in where it goes, and every time you weld, not over 1 to 2 seconds, then take a air hose and hit the weld with air, holding the air about 1/2 inch from the weld, to cool it.

Do each weld like that, untill all is done.

Pull the plug in the cap and drill to 3/8's.

A 5/16's pipe should be drilled out to 3/8's any way.

Herm.

 

[Phil Brown]

I'd be more afraid of the JB weld failing than damage to the babbitt from heat. A damp rag on the babbitt is a good idea to help keep it cool. I used brass rod because it flows at a much lower temp. than any steel rod, and when you use it with a TIG machine you have fantastic heat control. you still need to weld (or braze) in short segments with cooling breaks between. Another trick to use is to extend the argon post flow to help cool the area when you stop the arc.
Also because of the way i had to fix the one that I had I could not use the "stock" drain tube so I used some 3/8 tube (.375 OD) that had an ID of .308 not the normal .285 , figured it couldn't hurt as it's a pressured oiled motor with just the stock slinger back there.Working good and dry so far

 

[Bob Bidonde]

You can run without the drain tube if the hole in the rear main bearing is open. Ford did not tack weld the tube to the bearing. Rebuilders most likely did that.

If you are going to replace the missing tube, use the 3/8" diameter one. Be careful not to inset the tube too far into the bearing because it will impede the drain oil flow.

I fixed a cracked rear main bearing with JB Weld and it worked for many years. So if the area is thoroughly solvent cleaned, the JB Weld will work. If the tube falls out, no harm done as the engine will run fine.

 

[James Rogers]

Vince is correct on all counts. If the tube is incorrect length or missing, it will leak and sometimes profusely. The thread for the tube is 3/8-32 and the tap is available from MSC. The small thread is a comparable 5/16-32 and can be found in the same place.

 

[BILL WILLIAMSON]

WTHOUT the tube, I would "imagine" that the WILD SPLASHING above the dipper tray, would FORCE oil back into the hole & cause the rear main to leak MORE???
Bill W.

 

[Bob Bidonde]

My experience running without the tube differs from Vince's because there was no excessive leakage out of the rear main bearing. I won't argue the science of the drain tube, but I have two NOS Ford bearing caps with tubes and no tack welds.

 

[Kohnke Rebabbitting]

All factory rear main caps put on new engines, pipes were spot welded one time, or one place.

There were new, or rebabbitted caps, in semi, that had no pipe, or a loose pipe that needed to be finished, and align bored.

Herm.

 

[Fred K-OR]

Thanks to you all for the help.

My friend pulled the rear main cap off and found the Babbitt is in bad shape along with the hole when the drain tube fits in.

So tomorrow we are going to pull the engine and take it to a rebuild shop to get it checked out. I will see if I remember how to pull an engine. Think I can at least "supervise" the operation.