Babbit woes
 

Disassembled my "A" engine for issues. What I did not expect to find was problems with the main bearing Babbitt. I would estimate about 3000 miles on rebuild including crank regrind and new Babbitt. the center main cap has a piece broken off about 1/4 of the total area. (Sorry no pictures) I pried the remaining Babbitt with a pocket knife to see if the material was brittle. The material is not brittle however the rest of the bearing came off the cap. There is evidence of oil between the bearing and cap. I tried the front main cap and the bearing came off as well with a film of oil between the bearing and cap. The rear cap is ok. There is a nasty vibration at around 800-1200 rpm range that I try and drive through as soon as possible. I do not lug the engine plus I am careful not to advance the spark too much. There is no evidence of detonation on the spark plugs nor pistons. Can someone help me here on what happened. Daren

Re: Babbit woes
 

The caps may not have gotten a good enough tinning during the rebabbitt process. The caps are about the only part of the main bearings that can be tinned. I'm far from a person that can tell you for certain but others more experienced may be able to add their thoughts.

Re: Babbit woes
 

Pictures would help!

If the caps were not tinned, you can pull babbitt easy.

If they were tinned, could been a bad job, as many Guys ( By all the you tube videos ) have tinning flux on the cap, and the babbitt will not stick 100%, as it has oxidized.

Or the cap was tinned OK, but many times, in the you tub videos, the cap, or mandrel was the wrong temperature, as when the two meet, they will not bond.

If the block, and rear cap is cast, if I had pictures, I could tell if they were peened.

Re: Babbit woes
 

Pictures of cap failures.

Herm.

Re: Babbit woes
 

I will work on getting pictures. There is a good chance they were not peened. Would skipping the peening process affect the bonding? Any chance the fracture was caused by the bonding failure or could the fracture take place before the bearing let go.

Re: Babbit woes
 

I uploaded a PDF of an article in this post that discussed one version of the Babbitting process. Here's what it says about peening:

Re: Babbit woes
 

Alexiskai excellent information. Daren

Re: Babbit woes
 

There really is no bond on cast iron, what it amounts to is a very hard crimp from the babbitt, to hold on to the bearing shell.

Many think the Anchor holes, were put there to hold the babbitt in. Not so, they were put there to keep the Babbitt from spinning, just like a Locking Lip, on a modern Bearing. If the babbitt is loose in in the shell, it will also be loose in the Anchor holes. If not peened right, there is gap between babbitt, and the shell. What happens then, the crank peens the cold babbitt, and breaks it out, and then breaks it up.

Another thing, on a Chevy 4 Cyl, and the Olds, 4Cyl the front, and rear bearings are solid Babbitt, front, and rear. They are not peened, and have a lug that goes in the block to keep the bearing from spinning. The bearing is poured on one of our machine jigs, that compensates for the shrink, that is a perfect fit, to the bored mains. The bearings are held in place with there shims.

The front, and center main caps, there is a lot of things to go wrong. One of the biggest ones I see is using a cutting torch, used on heating a bearing, really, makes as much sense, carrying it around, using to light your cigarettes. The reason is, even if it were tinned properly, the hot spot of the torch, put close to the center, will burn, and turn the tinning to carbon with in 5 Sec. They would never see it, unless they knew what to look for, but what is the chances of that!

There is so many others things, but I don't want to bore you. The sad thing is, a Guy gets a new babbitt job and he puts 2,000 miles on the babbitt, and it goes bad, but he only drives a few miles a year, or he misses a year or two. It could be 20 years before he knows he got screwed.

The bottom line is, get your money back, don't let him do it again, looking for a different out come.

Herm.

Re: Babbit woes
 

You're not that far from Clare, Iowa. Take a day trip and haul your block and crank down to Kohnke Babbitting.

Re: Babbit woes
 

I am under the impression the caps are not cast therefor can be tinned is this correct.

Re: Babbit woes
 

The front, center caps are Steel in all years, the rear cap is Steel early, cast later, the steel caps are tinned, the iron rear cap is done the same as the block, and has to be peined---
The picture is what you would get back in the day at the dealership when the krw system was used, new factory caps, you can see the indentations from the factory peining which were large washers pounded in with air hammer

I had a lot of trouble getting a good bond trying to pour caps, many failures---- but like Herm said, using a torch won't give the temperature control that is needed

Re: Babbit woes
 

Re: Babbit woes
 

We are about 5, to 6 mounths out all the time.

Herm.

Re: Babbit woes
 

No, not at all. Only cast iron can be peened, as if you try to peen a tinned bearing, it can bust the bond between Babbitt, and the tinned shell, or the tinning, from the shell.

Herm.

Re: Babbit woes
 

Some confusion here. What you are saying is the front and center caps are steel and you should not or do not peen them. Both the front and center caps shells came loose and i was under the impression the failure could have been from lack of preening or not heated properly. Kohnke what is your opinion on what happened.

Re: Babbit woes
 

Correct: You do Not peen the front/center steel caps as they are tinned and the babbitt is fused to the tin does not need to be "peened" as Herman has mentioned.

If the Babbitt broke away on the center and front cap it may have been improperly done, wrong heat is usually the case.

Re: Babbit woes
 

You treat the steel caps the same way as the connecting rods. The parts are smaller so shrinkage affects them less. Tinning is a solder procedure that allows the babbitt to stick just like solder would. Folks that do a lot of soldering learn quickly that a proper tinning will allow for a complete bond in the process. The babbitt is just as sensitive as solder about contamination. If there is any contamination it just won't bond on it. The flux has to be right in the process too since it is a process of tinning.

Con rods & caps are smaller parts that can be heated & tinned more quickly and uniformly but a person has to use a procedure that will insure the uniformity. This includes heat and cleanliness. The parts have to be the right in the correct heat range and clean as a whistle.

Re: Babbit woes
 

Started inspecting my engine since I had it out (rebuilding transmission and new clutch). Dial indicated the mains and the cam and numbers seem decent, 0.0015”-0.003” on the mains front to back and 0.0015”-0.0045” on the camshaft back to front. Pulled the rear cap off and found cracked babbit with a dime size piece loose. Not enough tinning or peening? Haven’t been able to pull the other caps yet until I can get an 8pt socket.