JB Weld on crank end housing?

[James Rogers]

It has been my experience that there are 2 things that lead to this problem. The first is when someone gives the crank a serious whack with a BFH and misses. The second is when the flywheel bolts are mixed up with the transmission rear bearing retainer bolts and tightened against the flange. This breaks the flange because while the bolts look considerably like the flywheel bolts, they are 1/4" too long and run up against the cap flange. It can happen if the dowel pin retainer is left out but mot every time and there can be other causes but these are the most common.

[Tom Wesenberg]

Originally Posted by John Stone

Is the rear main cap on backwards or am I seeing things?

I'm also wondering why the tin cover is all cut up?
BTW, it should be black not engine green.

[John Stone]

Originally Posted by John Stone

Is the rear main cap on backwards or am I seeing things?

I think what threw me was the size of the cap. It looks like a B engine. The flywheel housing inspection plate sure is trimmed to fit something other than an A rear main cap.

[J and M Machine]

Originally Posted by 1931 flamingo

I was reading a thread on the EV8 forum about endplay on the crank. Some were talking about welding and then machining on the crank. Is that possible on the A's crank or not. I'm thinking excessive end play contributes to rear main leaks??
Paul in CT

Yes to both questions: excessive play leads to oil leaks and Yes; the crank can be rewelded.
If It's excessive end play it's not the crank's fault, the babbitt is pounded out on the rear thrust surfaces and should get repoured and bored.

If the crankshaft' has excessive wear on its thrust surfaces,
Typically there's enough metal to regrind and make the crank straight again then by making up the difference in the amount of babbitt removed from the thrust of cap and block.

If it was a modern inserted crank the welding route would be the way to go to save the crankshaft.

[Rubatoguy]

So perhaps someone can clue me in, since I have never seen a B rear main bearing cap - the JBWeld looks like it is holding a section of the cap on - but I don't know if this is part of the casting, or a washer of some sort. I noticed it only had a shim on one side - aren't you supposed to put shims on both sides? And notice the fine crafting to fit the B block to the A bellhousing...

Todd

[colin1928]

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Where is the front thrust ??

[Ross/Kzoo]

Originally Posted by J and M Machine

I'm a bit surprised as usually everyone sings the praises of JB weld in this chat room.

I, personally, think that are places for JB Weld but this is not one of them. Most proper places for JB would not be spinning @ 500-2000 RPM.

[BrianBurkert]

I'd have to get a rear main cap out and look at it, but at first glance it looks like they glued a large steel half-washer to the aluminum rear main oil seal. This an attempt to raise the "dam" and catch excess oil leaking past the bearing.

[Rubatoguy]

It does look like a large steel half-washer that is JBWelded to the end of the cap. I didn't know if that was a real factory part, or something that was creatively improvised. When my Dad got this engine back from the rebuilders some 30 years ago, it had a knock, and a local guy looked at the engine, found the bearing clearance way to loose, and part of what looked like a rag in one of the oil passages. It would consistently overheat after driving about a mile. At this point, I wanted to familiarize myself with the engine before I took it to a competent rebuilder so I know what to look for. I'll post some piston photos later.

Todd

[BrianBurkert]

Yes, it looks like a creative improvisation. Actually, I made a wrong statement above as I now recall the only aluminum part of the "rear main seal" is the upper half of the seal that's in the block. It looks like they glued that washer onto the forged/cast rear main cap. It probablywouldn't have caused any harm unless it came loose.

The Model A design allows some excess oil to get by the bearing. It is supposed to be collected by the grooves in the seal and returned to the oil pan via a tube. Sometimes when parts are slightly misaligned, or the bearing is a little loose, excess oil overwhelms this collection system and you get excess oil leaking onto the ground. This looks like a Mickey Mouse fix to catch that excess oil.

[Kurt in NJ]

Perhaps it was cut off then glued back on because of not having the proper tool to cast the babbitt,also--- no oil grooves, crude oil well at the parting line that goes all the way instead of ending about 1/4" from each flange

The pictures are of a NOS factory cap, note how the oil grooves go around the front thrust, that front part of the groove is cast in, meeting up with the machined groove for the bearing surface,

[MALAK]

Originally Posted by John Stone

I think what threw me was the size of the cap. It looks like a B engine. The flywheel housing inspection plate sure is trimmed to fit something other than an A rear main cap.

Originally Posted by Kurt in NJ

Perhaps it was cut off then glued back on because of not having the proper tool to cast the babbitt,also--- no oil grooves, crude oil well at the parting line that goes all the way instead of ending about 1/4" from each flange

The pictures are of a NOS factory cap, note how the oil grooves go around the front thrust, that front part of the groove is cast in, meeting up with the machined groove for the bearing surface,

A couple people allured to it but I believe you have a B engine. Kurt your photos are of a B cap.
Todd can you post more pics of engine? Specifically the valve cover area.
Notice how the B caps bulge out in the seal area whereas the A caps are nearly straight.

1st pic is A cap.
2nd pic is B caps.
3rd pic is A crank in cap
4th pic is A crank in block without seal.

[James Rogers]

OK, the investigation continues. My take on this is after the babbitt was poured and cut during installation of the flywheel,someone put the wrong bolts in the flywheel and broke the rear of the cap. Being cast iron, the cap is pretty fragile in this areaandpretty easy to break. Instead of starting over and doing the job correctly, they just carved the broken piece out and used a half washer to replace it and glued it in with JB Weld. Not having a groove in the babbitt is a true sign of a shadetree mechanic. The Model B engine had double grooves the led to the front thrust area because it has a small amount of pressure directly to the bearing and if it didn't have a way torelieve this pressure it would overwhelm the rear slinger and leak bad. I would suspect this one leaked.