Crankshaft binds after engine hot dipped

M

moasew

Senior Member
I just had my block hotdipped with the babbitt .It wasn't left in too long as the shop didn't want to damage the babbit.However I'm thinking it might have been distorted as my crankshaft with four shims in it still does not want to hand turn when caps are just snugged up and not even torqued.

Has anyone expericeienced this? I can't think of what else might be causing the binding.
 
Do you have the front two caps on facing the same way as when they came off? A little machinists blue should reveal the problem spot(s).
 
The caps are placed in such a way to match up with the grooves in the babbit in the block so should good.I tried switching the front and centre caps but no luck.I'll try the prussian blue as well.Thanks.
 
Not just front and center caps accidentally swapped. I mean each accidentally rotated 180.
 
For those that do not know. When you take a engine apart all ways number the main caps. I mark them on the front. 1,2,3 on an A. Also mark the rods,and caps. most mark them on the cam side. Now you can put it back together the way it was. You can not switch caps around and end up with a good job.
 
Last edited:
I had the caps turned 180 but they didn't seem to line up good with the oil groove in the babbitt when I had the crank out. Maybe this doesn't matter?? It shouldn't take much work between the two caps to switch around and see which way they fit the best.
 
What do you mean by ' still ' does not want to turn ? The fellas are right, the caps need to be marked so they can be reinstalled correctly.
 
You were right to line up the oil grooves if the caps are not marked. Do not switch the front and center caps back and forth.
I assume too you did not keep track of the shims when you disassembled it. Put in shims one cap only at a time, same number of shims on each side, until you can turn it. See what the clearance is with Plastigage. You are looking for .0015-.002. The Plastigage should hopefully squish out (nearly) even all way across. Use Prussian Blue to find the interference point if necessary.
Keep trying and fitting and you might get lucky, but I am sort of pessimistic about it. Are you going to have the same problem with the rods, ie, not marked? Measure them when you replace them too. At least the babbitt is not damaged. But, now you know you should not hot dip babbitt, should mark the caps, and keep the shims as they came out, for both rods and mains. Call it a learning experience if nothing else. I have had some expensive ones myself.
 
Did you save and mark the shims located between the main journal caps? The shims are used to adjust the clearance between the crank journal and babbitt and to allow a thin layer of oil to flow between the two surfaces.
 
It pays to do a little reading before and during working on an engine. These engines are easy to work on, but also easy screw up, because, while they look simple, they are actually precision mechanisms. Proper procedures, sequences and tolerances must be adhered to, and there are books that can help even an amateur through the process. But, as Clint Eastwood so accurarately observed, "A man has to know his limitations." Weigh what you think you know against what you must know to do a good job, and proceed accordingly.

I approach all my work with the hippocratic oath: "First, do no harm."
 
1930 coupe said:
Babbitt will get soft and start melting around 450 degrees, The chemical could have reacted with the Babbitt and caused it to swell or separate from the block. It is not a good idea to put Babbitt in a hot tank solution, it usually destroys the Babbitt.
Click to expand...

X2 it is the chemicals time new Babbitt
 
Yep, hot tanking destroys babbit, so any time in the tank had to do some damage.
Do you have any pictures of the babbit in the block and caps?
 
The caps or crank were not dipped and the babbitt on the block doesn't look any different than before dipping.In fact I had an 84 yr old gentleman who has worked with engines/babbitt for yrs look at the block and he thought it looked OK.As I mentioned the shop where I had the block dipped didn't keep it dipped too long so I had to manually remove alot of old paint. If it wasn't in long enough to remove the paint chances are the babbitt is OK.I will investigate 1930 coupe idea of the radius and diamond..This should at least get my caps in the original location. Do the exact same shims have to go back in each side or just the same number (four per side)?They appear to be all the same thickness.I will also check with plastigage (had once before) and prussian blue. I also had kept track of the caps as they came off but with moving stuff around obviously they got out of order:(Thanks to everyone for your comments and help).
 
It dosn't take 5 minutes to kill the outer layer of babbitt.

Unless paint was layed on over grease and oil, it will not come off or all come off with out putting the block in a sand blast cabinet.

Babbitt does kill chemical fast, and vice versa.

So now, you have a hard, distorted, brittle outer shell on the bearing surface.

If you were to melt the bearings out, the outer surface would separate from the rest of the babbitt underneath, like slag.

Half the thickness of a human hair will stick a crank good.
 
OK I have the crank turning by hand but I have one set of pop can thin shims in the front cap,7 sets in the centre cap and four sets in the rear main.The crankshaft seems to bind when turning it though(: I would think it is very unusual to have that many shims in one spot and not another. I think I need to find someone who will rebabit but no one local does this.I'll have to go out of my Province for this.
The Prussian blue seemed to show even contact on the front and Centre but on the Rear Main; contact on the rear of one side doesn't seem to be made.
 
Patrick L asked "What do you mean by ' still ' does not want to turn ? The fellas are right, the caps need to be marked so they can be reinstalled correctly."

Patrick.. I just meant it still wouldn't turn after adding up to four shims per side as opposed to one or two shims but you can see from my last thread I have it turning but not under good circumstances.
 
Does Prussian Blue show cap or saddle contact or both? Sounds like starting from scratch might be the way to go. You might want to have the crank checked for straigtness while you are at it. Yeh, I know, you did not dip the crank, but check it and then you do not have to worry about it.
 
You must log in or register to reply here.
Back
Top