[Louvered97GTP]

Id like to change THREE things here.

ONE: I would avoid turning counter-clockwise unless you absolutely have too. For one thing, theres no way you should be able loosen the crank bolt thats ~150ft/lbs tight when it should only take ~20ft/lbs to spin a motor over.

Secondly, and most importantly you will back feed the oil out of the pump, and can loose your prime. Not something you want to do.

Last thing, having oil on the back of the bearing isnt goona hurt anything, heck when you pull the bearings out at rebuild time they are always wet anyways. The tabs hold the bearings in place and keep them from spinning. Oiling the whole bearing makes it easier to get in and wont hurt anything. NOW, THAT SAID - when building a new motor or even replacing bearings like this, IF YOU ARE plastigauging the bearings, you dont want to oil the backs as the oil takes up clearance and will give you a false reading. I have been building engines for over 20 years, I have never seen a dry bearing backside from an engine that has been run. So whether you oil it to get it in, or it gets oiled running, its not goona hurt a thing.

Hi gn2beatu,
Yes you are correct about not being able to loosen bolt, when I originally made write-up I had a loose bolt because I had pulled timing cover off, thus the discrepancy. Thanks for catching this.

In regards to feeding oil back into pump and loosing prime. I had assumed any GTP modder that is brave enough and talented enough to do engine-work of this magnitude understands by now that rebuilt engines never get fired without first disconnecting coil pack harness, and cranking the engine to prime it. For those who forget to oil the cylinders, a shot of WD40 in each cylinder with the help of flexible vacuum hose is a descent alternative. So no real danger in crank direction rotation as long as engine is primed before starting.

I respectfully disagree on oiling the whole bearing to make things easier. Last time I checked, oil is very slippery and hard to work with parts when things are sliding all over the place. And a spun bearing does not respect the locking tabs, so I prefer caution over carelessness because I don't want to do this process again in few weeks if I can help it. However, the point of keeping a clean backside on a bearing is to avoid getting any kind of debris on there that would begin to form scratches. I did find premature wear on a bearing I replaced this way where I did not take good care to be careful in keeping backside of bearing clean. That's one of my lessons learned.

I may be redoing this procedure again in next few weeks, so I will take photos and post if you guys are interested, as well as adding any other "lessons learned" by all who helped contribute to this post.

Thank you,

 

[tylcarroll]

rod bearings

This article made me very happy knowing that I don't have to pull my motor to do rod bearings, however I have a 2004 gtp comp g with the L32 motor. Can I still replace the bearings with the motor in the car?

 

[Louvered97GTP]

If it's the same series II bottom end and cradle design it should be same procedure. However please understand this isn't exactly easy, and time and patience are critical because there is a risk of one scratching the crankshaft journals. I never had an issue but I've had plenty of practice. One friend tried this and scratched his crank journals with rod edges as he rotated crank into place.

On one of my last times doing this, I was sloppy and installed a bearing wrong so make sure you're careful or this could go very badly.

It takes some skillful maneuvering to get the oil pan off and on. So again, patience is required, but this has been done many times by a few.

Good luck.

 

[jmaechtlen]

questions and comments
(1) you can rotate the engine either way by using a screwdriver against the ring gear.
(2) Ok, I guess if you might get lucky and catch it while the crank journal is still ok.
(3) the tty rod bolts - besides GM, these guys offer them:
OEM GM Parts Online | Wholesale GM Parts Online
still pricey - how come everyone selling inserts doesn't also sell the bolts?

The motor I'm prepping is from an '02 Bonneville - each rod bolt has an interesting section (looks like an oversized thread) that fits tight in the cap and aligns it to the rod.
The inserts had some particles embedded in them, so I will treat it to new rod inserts.
fwiw

 

[ZEN357]

Thanks for the information. Nice to know.

 

[DAHL]

I recall years ago that my dad did a bearing, ring and valve job on his Cadillac while it was still in the car. It ran well afterwards so the rebuild was a success. I guess it can be done but I cannot see how main bearings and the crankshaft can be replaced this way without great difficulty. I've done my share of engine repairs when the block was on an engine stand but I guess the OP was successful.

 

[mr goodwrench]

Hummmm, this bearing process is not nearly as difficult as one might think. Being VERY OLD SCHOOL I too have done rod and main bearing replacing. As far as the main bearings go, all the main bearing caps need to be loosened enough for the crank to drop down a little. Then one would use a relatively small screw driver gently tapping the edge of a main bearing on the opposite side from the locking tab that holds it in place(from spinning in the block). Once you get the bearing out a little, one can then use a medium size screwdriver and get behind the portion of the bearing now sticking out a bit and carefully twist the driver blade against the bearing and it will move out following the crankshaft journal. As it gets most of the way out, it gets easier to move until it's free from block and crank. OH BY THE WAY, ALL the other main bearing caps do need to be loosened so there is a little clearance for bearing removal/rotation. Once it's out, simply remove. Then spray a little brake cleaner(this evaporates very quickly) and then oil up the new bearing and rotate it into the block until the ends are just about flush with the block surface. Repeat this process on all the mains one at a time. Once it's done and torqued to specs, you can now do one set of rod bearings at a time just about the same as the mains were done. When you are doing the rods, the process is the same as the main bearings.

Another note about rod and their bearings.......if you want a good successful job(especially on the rods), the pistons and rods should be removed for reconditioning the rods before installing new bearings. Connecting rods have an inherent condition from use which is the "BIG END" OF THE ROD AFTER MANY MILES OF USE develops a slight out of round condition(which is normal for most engines. If the big end of the rods is not re-machined for being perfectly round, this can end up with excess bearing wear and all your work may be for NOT. When doing a full rebuild, the block and main bearing caps are remachined and line honed for perfect alignment and bearing clearance.

Being old school, many of you guys probably don't fully get all of what I mentioned. If that's the case, don't even try this job without any experienced help. Hope I didn't bore you guys and gals. Best of luck if you give it a go.

Jake

I personally would rather pull the engine and disassemble and clean before doing a bearing replacement job. For sure recondition the rods and get some GOOD AFTERMARKET ROD BOLTS......

 

[gtx500hp]

Always brutal working flat on your back. Well worth pulling the engine out.

 

[DAHL]

Yes you can successfully replace a worn rod bearing on the car, but its a good idea to check the journal to see that it is not out of round. If it mics up to spec all around then by all means polish the journal with 1000 grit paper, then clean everything well ,replace the bearing and torque to spec. . I've known several guys that did it this way and the repair lasted for thousands of miles. Its not a typical repair but it works.

 

[mr goodwrench]

One other thing I would do would be to use some "plastic guage" to check for proper clearance. Plastic Gauge is a soft plastic one would put on the crank or rod bearing and torque it carefully. After doing that, gently remove the rod bearing cap and check the plastic gauge width after the torquing process to be sure the clearance is correct. Normally when doing an internal engine repair like yours, checking for proper clearance can be a critical issue if clearance is incorrect OR the rod might be OUT OR ROUND.....which can happen with a bearing failure. Good luck,Jake

 

[Olds64]

I personally would rather pull the engine and disassemble and clean before doing a bearing replacement job. For sure recondition the rods and get some GOOD AFTERMARKET ROD BOLTS......

x2

BTW, excellent thread with good info. :goodpost:

I recall helping my dad R/R rod and main bearings in the garage with the engine still in his 1991 Hyundai Excel. I was still in in high school then so crawling around under the car was no big deal.

 

[VignalDimnage]

:icon_surp

Asking from a non-car guy. What is a pick up exactly..

 

[mr goodwrench]

A pick up is a 1/2 or 3/4 ton truck with a bed in the back portion of the chassis(behind the cab)...... there are several different ways to use the word "PICK UP".

 

[jmaechtlen]

Heh - I see that dimnage has showed up again - posting spam links as usual. I guess that's why mr goodwrench replied that way.
I cleaned the oil pickup well before re-installing, can't even remember what kind of gasket or o-ring it uses.
Mine made a solid 60 psi of oil pressure when cranking with the plugs out. Several thousand miles later, it runs fine and no signs of bottom end issues.

 

[jmaechtlen]

Replacing main bearing inserts -
An easy way to drive the old top insert out is to bend a small cotter pin so the head can go into the crank oil hole and 1/8 inch or so of the legs are bent at right angles so it can't fall all the way into the hole.
Then rotate the crank so the legs catch the edge of the bearing insert and pushes it out. (obviously turn it so the tang comes out instead of trying to push it through)
This lets you push the insert out without possibly damaging the crank's bearing surface.
cheers
Jay

 

[mr goodwrench]

Lower bearing
New pair of clean gloves again. Install the bottom rod bearing into the rod cap. Lube the bearing, and place it back onto the journal with a rod bolt in hand. Thread the rod bolt to hold it in place, but do not tighten. Install the second bolt and alternate back and forth as you tigthten the rod bolts with maybe 4-5 turns of the ratchet before switching sides so the cap goes on fairly even. Is this necessary? I dunno, do you want to risk doing this again?
tighten snugly but don't overtighten, that is what the torque wrench is for. Follow the recommended torque settings and torque down to spec.

Viola, that's it! Now continue doing the rest one at a time. Once you finish the last rod, go back and double check the torque on all the rods since you have spun the crank around completely while getting to the last rod.

There is one step not mentioned, that would be to check the crankshaft journal DIMENSIONS(ROUNDNESS). This dimension should be the same as OEM deminsions. Also, the crankshaft journals should be completely ROUND(us a micrometer to check that dimension in a few different positions). This dimension should measure the same from different angles when checking the journals and it should also be completely free of any scores or groves. If this is not what you see or measure using a micrometer, there's a good chance the crankshaft should be re-machined so bearing failure does not re-occur. My 2 cents. I've been in the auto service industry for 50+ years and seen just about everything. Making sure the crankshaft is right on OEM dimemsions is a MUST. If not, you repair may not be very long lasting............ Best of luck, mrgoodwrench (Jake)...........

PS, get back to us as this repair goes. One last thing that also should be done is to PRE-OIL the bearings during installation and use some plastic gauge when torquing the rod caps. This will show if the bearing to crank clearance is correct. You should check with some good service manuals to see what the clearance is suppose to be. IF YOU FOLLOW THESE STEPS, you repair should be good and last for a long time.

 

[gikobeb]

Very detailed guide for rod bearing replacement. Thanks for the sharing.

 

[DAHL]

Great write-up but I would like to add, if you decide to do it this way, try to mic up the crank journals to insure that they are not out of round. Measure from top to bottom and then side to side. You can do this with a set of calipers. I would also check for deep scores before moving forward.