OT: Babbitt bearing failure mode

These photos are of the mains in an early flathead Ford. The first photo is of the center main. The Babbitt wiped out of the bottom, and material broke out of the top and piled up in the bottom closing up the vertical clearance, but leaving clearance at the sides. This made a really odd knock swinging side to side and was hard to diagnose, but that's another story.

The second photo is of the rear main, you can see pieces missing and more cracked and ready to leave. The missing pieces stuck to the oil on the crank and lifted out with the crank.

I've only scraped existing bearings, I've never poured babbitt or seen this kind of failure where the material falls out of the casting. Is this a typical failure, or were they incorrectly poured?

The engine is a '36 in a pickup I bought in '72 but haven't driven much until recently. I bought it from the original owner who drove it every day. He told me the original engine was replaced by the Ford dealer with a Ford rebuilt engine because of a crack. There's a metal tag riveted to the bellhousing that could be a rebuilder's tag, but it's unreadable. The cylinders are standard size, so if it is a rebuilt it must have been a very low mileage engine to start with. The crank is standard size and looks like you could polish it and reuse it. By the crud on the outside of the motor, I'd guess the motor was put in about 1950-1955.

Anyone have experience with this? I'm wondering what the likelihood is of this happening again, if I rebabbit the block I have.

In the 1st Pic, it looks like the shell hasn't been tinned and it was the wrong / poor babbit or hadn't been stirred up before pouring.

The 2nd's been tinned better but the babbits bad.

Mud,

Pardon me if this is a stupid question, but aren't those inserts? It looks to me like I can see the steel shells. If they are, why not just replace them? In the (not too distant) past, flatty parts were plentiful and cheap, unless you were so unfortunate as to be looking for over/undersize rod bearings.

Far be it from me to ever question Limy Sami's wisdom, and I am not, but could the wear you see be caused by a badly fitted bearing, with the crankshaft banging around in there for a long time, hammering the bearing material into the mess you see?

Steve

edit: I just looked at the picture again and what looked like shells before all of a sudden doesn't. Plus thinking about it a little, I think I remember that the early engines did indeed have poured mains. Never mind!

Babbit Failure

I have seen similar problems in pre-war Rolls-Royce engines quite a few times. There are a few issues present, first being metal fatigue, causing cracking and eventual breakaway of the babbit. Second tinning issues, thirdly, babbiting process flow out or temperature issues. The last issue of extreme wear could have many causes such as a dry start after extended periods of non-use.

Years ago a lot of shops did babbit and most often reused what they melted out of old bearings - an absolute no-no for mains. The Rolls used babbited shells and shims allowing very accurate fitting but a pain to do. There are a number of specialist shops who can reline blocks and shells for reasonable costs using new babbit. Then get a good shop to line bore to clearance. Little scraping in will be needed.

Peter

Those look like inserts to me, check here ---> 1936 1937 1938 Ford Engine Main Bearings

sa100

I think you're seeing the shims edge. I also think you may be right about the beating. The bearings could have been loose from the rebuilder and never checked. The rebuilder could have replaced a broken crank with a new one and not checked the bearings for true.

It does look like varnish was under the babbit though. Would lead me to believe the material separated long ago.

I know a man who had half a dozen in his shop 4 or 5 years ago. He's in southern Md. If you want me to check for a possible replacement I will.
Let me know what you have if you need one.

Ben

I type too slow! I guess they had shells and shims, cause the pic sure looked like shims.

See the brass shims? Babbitt!

Lots of good Babbitt folks - the remaining hundreds of thousands of Ts and As all have to be repoured form time to time.

Here is one:

Connecticut Antique Engine Restoration, LLC

Ford changed from poured to inserted bearings sometime during the 1936 model year. The late 36 block is the same as a 35-36 block except the crank mains are .400" larger in diameter, and the block bores are bigger and accept inserts. The late 36 blocks are rare and hard to find, even harder to buy if you find one. Once you find one, you then have all the problems of the original flatheads like cracks from the exh valve to the cylinder wall plus the issues of 65 year old car parts. This engine is in such good condition it would make sense to reuse it, but I don't want to build something I'll regret if the mains go away again. I'm contemplating boring this block to take inserts, but the main cap studs are farther apart to accommodate the larger bores, boring these may touch the studs. I already have a complete 37 engine of unknown condition here which can be rebuilt and installed by blocking off the block mounted water pumps and installing the 36 heads with the waterpumps mounted on them, but it's not correct for the truck.

Leadfootin said:

I have seen similar problems in pre-war Rolls-Royce engines quite a few times. There are a few issues present, first being metal fatigue, causing cracking and eventual breakaway of the babbit. Second tinning issues, thirdly, babbiting process flow out or temperature issues. The last issue of extreme wear could have many causes such as a dry start after extended periods of non-use.

Years ago a lot of shops did babbit and most often reused what they melted out of old bearings - an absolute no-no for mains. The Rolls used babbited shells and shims allowing very accurate fitting but a pain to do. There are a number of specialist shops who can reline blocks and shells for reasonable costs using new babbit. Then get a good shop to line bore to clearance. Little scraping in will be needed.

Peter

Click to expand...

This truck sat from 72 until 3 years ago and was only started once in that time IIRC. (I never understood how someone could let something like this just sit without touching it. Now I'm that guy ) It ran well for one summer. the next summer it started to knock, It was parked all this last summer. When I first got it out I was very concerned about starting it for the first time, but it survived and lasted one season. The only sign of heavy wear is the center main cap, and I think that's the babbitt failing, not a lube issue. All the rest upper and lower bearings are unworn, just cracked and flaking. I'll post 2 more photos, of the rear cap and the front upper.

I bent a piece of the thrust bearing surface that broke off, it bent 90° in my fingers like a heavy piece of 5052 aluminum without cracking.

I have seen a similar failure on a 40's Dodge with insert bearings.. The babbit just did not adhere to the shells properly...

Have it redone by a shop that specialises in babbit and be done with it.. Babbit worked fine for a long time, just is a pain to re do..

I have a similar situation with my big Wisconsin engine. The rod caps and Main's are all babbitted bronze backed shells. All have cracked babbitt or chunks missing.

Some may be due to a lack of proper tinning but I beleive a lot of it, in my case, is simply a lot of hard use. All the shims were in place so I doubt if any adjustment was ever made for wear.

Eventually (when the piggy bank is sufficently full) I will send the shells out to be re-babbitted then scrape them in. The crank will be turned and trued-up as well.

Below is a photo of one of the rod caps. They are 4 bolt rod caps and measure 3-1/2" long and 2-5/8" in dia. The rear main is 5-3/4" long

Limy Sami and Leadfootin are close enough on this one that not much else needs to be said, but- the cap was tinned but it appears that the cap was too cold when the bearing was poured and there was a poor on non-existant bond between the cap and the babbitt. It probably would have failed regardless, as it appears that either the babbitt was severely overheated or the bearings were poured using old babbit. On early V-8s the block is not tinned and relies on anchor holes amd grooves in the block to retain the bearing, but in this case the metal was so brittle that it cracked. Could be the block side was never peened properly after pouring and oil got between the babbit and the block and the cracked babbit is due to fatigue, but I realy think the babbit metal used is to blame for this one. You can also see on the thrust face where the babbit did not bond to the cap- again probably due to a cold pour. George King at Connecticut Antique Engine Restoration has a good reputation as far as anything I have heard, and he is close to you. To answer your other question- the poured mains will hold up fine if they are done properly and you don't expect to drive the truck 70 mph down the interstate.

Dan

Coolant/water in the oil at high temps cause a similar thing on modern inserts type bearings. Seeing as how this is an older casting, the were notorious for cracking just about everywhere....how did the oil look when drained?