removing rod and main bearings


johnny boost
Aug 15, 2001
What is the trick to removing you upper rod and main bearings with the motor inside the car? I have a 112K, on the GN, and would like to replace the bearings and rear main. There are some tricks used in the past such as fabricating a tool to stick in the oil holes, in the crank, and push the upper bearings around and out. How do some of you do this?? TIA

Mike Banas
I take the motor out and turn it upside down to do this!

Not the answer you wanted, but the crank has to be loose and hanging. One slip a a scratched new bearing [or crank!] can really ruin your day. Guess I am just cynical in re-doing lots of patched work other people do [including repair garages] trying to save money or time.
1-2 hours of work to pull the motor and do the job correct the first time. It will be much easier;) Frank
Not a big job.

I just did the crank and rod bearings in my 60k ttype.
They were pretty shot.
When I took them out I noticed they were marked std and .001. Mixed.
Anyway,make a long story short,the hardest thing about the job was getting the torque wrench on the no.1 main cap.
They make a tool that looks like a nail that inserts into the oil holes in the crank.
I couldn't find one so I used a cotter pin with the loop part crushed down on itself to end up looking like a "T".
You first drop all the caps slightly just to let the crank gain some play.
Remove and do one at a time but leave them loose till you are ready to tighten them all.
Insert tthe cotter pin in the oil hole and turn the crank.
Out comes the top bearing while the crank turns.
Same thing to put them in. Although mine went in without to much effort.Mostly pushed in by hand.
The rods don't need this method.
Take off the rod cap and push the rod up into the block.The bearings come right off.
Do the reverse to assemble.
Be very careful not to nick the crank.
I put .001's on the mains and std on the rods.
All the clearences for mains and rods were between .0015 and .0020
Oil pressure went from 10psi, hot at idle to 27-30 psi at idle hot.
You have to drop the crossover pipe and trans shield.
I did not remove any motor mounts but did remove the oil pick-up tube.
That was also a little hard but i have small arms and just reached into the pan and removed it.
I replaced the tube and the rear main seal also. Anything else you need to know drop me an email.
I am not saying this is the best way to do the job but,it worked for me.,It wasn't that hard and IMO beats pulling it.
Best of luck to you.
pull the motor and redo it on the stand-

this way you can tear the motor down to heads on, everything else off-
now you will have the time to wash out the engine bay, clean off all that oil and grime from the past 15 years-

doing the valve springs will take you less than 1.0 hours when the motor is on the stand!!! so your saving time right from the begining!!!

clean the block, headers,valve covers, blah blah blah ect ect ect--
maybe even pull the cam out and inspect the cam bearings---
my buddies car was running like a top-- we pulled the motor just to inspect it over--- good thing cause his cam bearings were shot
we ended up doing a cam, bearings, all the gaskets, and got it back into ship shape--- if we hadnt pulled the motor, then we would have never seen the bad cam bearings from the beginning-

ship your car to me-- i can do it over the weekend
If your oil pressure is good (especially good at hot idle) and no noise... leave it alone. You cannot get real good bearings for these engines anymore. GM discontinued, no H-series, only a few V-series... If your going to replace them anyway, I'd really suggest pulling the engine. It takes less than two hours. I've done a few in the car, but would rather pull. ..Just my opinion
I just took a motor to the machine shop yesterday, I will need
new bearings, I will use OE cam bearings, but what are you
\guys using for rod and main brgs, brand, etc, thanks, Ron
About the only think avalible are the P-series and there are a passenger vehicle and performance bearing in that series. Some people are using King bearings with OK sucess.
Hadav8, those FM bearings that you posted are what we need
to use for our cars, are these a quality bearing??, thanks, Ron
Originally posted by hadav8
F.M. Mains - 107M
F.M. Rods - 7120CH

Good success with these bearings.

These are good performance FM tri-metal bearings. Only available in standard and 0.010 under. Rather pricey too. We have used 3 or 4 dozen sets in 10 and 11 sec. GN's. These are getting harder to find as FM may not be producing them?

Another option is Clevitte 77 which is also a tri-metal bearing.
Hi, Nick, so when I get the call from my machinist, I should
spec the FM107M, and FM 7120ch bearings??, thanks, Ron
Just Finshed replacing all the rods and the mains including rear main seal. I cannot believe the rod bearings looked sooooo good. No copper, no pits, no grooves on a 113K motor. The mains had more wear then the rods but I was very pleased to say the least. I used .001" Clevite 77 bearings on both rod and mains. I could not believe its that easy with motor inside the car. Job took 2.5 hours start to finish. Had a GM mechanic showing me the tricks of the trade. Would do again in a heartbeat. Also NO MORE LEAKS, knock on wood.. :)
LC2 ,thanks for the email as your post was dead nuts to removing and replacing everythings.