replacing main bearings with crank in block
- Thread starter Slix
- Start date
hflwyo
Active Member
- Joined
- Jun 5, 2007
I have done it on large diesel engines but not on small engines or a turbo buick. Large diesel engines are made to be overhauled in frame. You pull off the bottom cap and bearing then make a tool from a cotter pin. Spread the open end of the cotter pin and stick the round end in the oil hole on the journal of the crank and rotate engine over and it will roll the upper bearing out. Do it again to roll new bearing in. Repeat procedure for each journal. Works slick on big diesel engines. Like I said not sure if it will work on Buicks.
Nice was wondering if I could use a hard wood dowel instead of something metal... Saw a post where someone said they made something specifically for this. Almost looked like a mushroom and the stem fit in the oil hole and cap stayed on top of the crank...
Are you doing this so that you dont have to remove the engine or do you have a little knock? If you've pulled off a cap and see any galling on the crank you'll probably need to pull it out anyway for a polishing. Unless you are the original owner or know the history of the engine you may be taking a guess on the size of the bearing also.
Motor is out of car on stand. Have bearing and shows wear. Not much but shows some wear. Was going to replace all rod and main bearings... Got the numbers off bearing...
Mains bearings stamped
18001493
GMM400
140F 632
Parts place suggested STD sizes:
MS960P main bearing set.
six rod bearings CB1228P.
Sweet made a u and used that to push them out... Wonder if I could use something like a strip of plastic laminate hate to scratch anything..
Guessing I should loosen all the mains and switch them bearing one at a time...
Hard to change the.oil seal with crank in block? thanks
Turbo Archie
Active Member
- Joined
- Feb 2, 2018
Why not just pull the front cover and do it right
1986 Buick GX1
GX1 #001 [The One and Only]
- Joined
- Apr 24, 2015
I changed my rear main seal with the engine in the car, crank in the block of course.
Got rid of the rope seal and installed the lip type back in the early '90's.
I thought it was fairly easy.
Got rid of the rope seal and installed the lip type back in the early '90's.
I thought it was fairly easy.
A ring type seal that just goes around the end of the crank?
1986 Buick GX1
GX1 #001 [The One and Only]
- Joined
- Apr 24, 2015
The rear main is a split seal. It works pretty well to offset the seal by 1/4" so the seam in the seal and the seam between the block and main cap DOESN'T line up with each other.
The one that goes in the front cover is a one piece seal.
Both available from www.kirbanperformane.com (search P/N).
Well, spent about an hour trying to figure out how to get the upper bearing out from under the crank and don't think it's possible without scratching something..
Loosened all the main bolts.and tried to push the bearing out with a piece of hard plastic... Didn't even budge as far as I can tell...
Almost seems like I need to pull the heads and intake and pistons and do it the normal way....
Just not sure about all that work. Bearings are definitely worn, not real bad but you can see the wear.
Someone suggested just changing the lower bearings and leave the uppers under the crank. Not sure about mixing and matching bearings like that...
Loosened all the main bolts.and tried to push the bearing out with a piece of hard plastic... Didn't even budge as far as I can tell...
Almost seems like I need to pull the heads and intake and pistons and do it the normal way....
Just not sure about all that work. Bearings are definitely worn, not real bad but you can see the wear.
Someone suggested just changing the lower bearings and leave the uppers under the crank. Not sure about mixing and matching bearings like that...
- Joined
- Aug 1, 2003
did you take the belt off ? nevermind..i see motor is out of car so why not pull the timing cover and chain and do it right as to the leaving bearings that might be ok for 2-3-4 but #1 is pulled up from chain and belt and definitely needs to be looked at ,,, just tap the bearing edge with a screwdriver it will roll out or put a bent cotterpin in the oil hole and roll it out with the crank
Last edited:
- Joined
- Aug 1, 2003
Screwdriver not a bad idea... Scared to scratch crank journals thou...
captndave737
Well-Known Member
- Joined
- Feb 14, 2006
I used a piece of an old bearing and forced it out rotating the crank. It was the thrust bearing. Rolled the new one up into place while the engine was in the car. Never drove it though which is a good thing because when I pulled the engine I saw I had spun the #6 rod bearing
Blown&Injected
Active Member
- Joined
- May 31, 2001
I too have used the existing bearings to push out the old shell in the top of the journal - it worked fine but did not solve the issue causing the bearings to be bad to begin with and thus it was all for nothing - good luck.
I tried it because I have seen it done in some plain old 1970's passenger car...Not so sure it is a good choice for an engine that gets stressed like a Turbo Buick.
I tried it because I have seen it done in some plain old 1970's passenger car...Not so sure it is a good choice for an engine that gets stressed like a Turbo Buick.
Yep for sure. Bearing were fine but figured while I was there.. ended up just pulling the crank and doing it right. Open up a mess if I scratch something...
