A main bearing question

Has anyone ever managed to replace the main bearing WITH OUT removing the crank from the car? I am doing an in-car engine rebuild on a 1995 Saturn Wagon w/ the DOHC I inherited from my sister. Based on info from a site called "saturnspot" the complete rebuild is do-able, but I haven't figured out this question on the mains yet. Anyone ever do this?

I've replaced the main bearings in a Chevy 4.3L without removing the crank, just took the oil pan off and removed the caps one by one and slipped the bearings out to replace.

In reply to EvanB: Thanks for the response. Would I need to loosen all the caps to allow the bearings to slide out easier? Did you have to tap them out or new back in? What did you tap with, if you did, to keep from damaging them?

I just loosened one cap at a time and tapped them out as far as I remember. I can't remember what it was with, maybe a thin plastic scraper? You just need to tap them far enough so you can grab one end that sticks out. On the 4.3 it was pretty easy to get them out and the new ones back in. If they are too hard to get out you could probably loosen the surrounding caps a turn or two to give you some space.

EvanB wrote: I just loosened one cap at a time and tapped them out as far as I remember. I can't remember what it was with, maybe a thin plastic scraper? You just need to tap them far enough so you can grab one end that sticks out. On the 4.3 it was pretty easy to get them out and the new ones back in. If they are too hard to get out you could probably loosen the surrounding caps a turn or two to give you some space.

I've done it by pulling the pan, loosening all the mains at least 3 turns so the caps wiggled, then pulled each cap one at a time and pulled bearing shells. The thrust main has been the worst in my experience to get the upper shell out, but nothing to break my faith in my ability to embarass myself. An old credit card is what I used to push the uppers out...put the edge on the edge of the shell and give the whole works a nudge. When the upper comes 'round enough to grab with needle nose pliers, grab it and out it comes. The thrust bearing required a love tap froma small hammer, via a long pin punch, to get it moving.

So yeah, it can be done, and no, it's not hard.

Never seen the inside of a Saturn engine, but it should be doable. I did it on both TR7 4 cylinder, and TR8 Rover V8 engines. Similar method to above, but once the bearing was loose, I put a used bearing shell behind it and pushed the old one out. Hence the term "rolling in new main bearings". Some STP helps keep everything slick.

I once had a set of tools made for just that purpose. Basically a pin with a flat head. The pin fit in the oil hole and the flat part pushed the bearing out by turning the crank. I think they were made by Snap On. In the old days engines were overhauled with the engine in the car. Not done much anymore. I remember having the rod throw turned while the engine/crank were still in the car.

In reply to Mikey52_1: Thanks all. Sounds like I can brave this. I like the credit card idea as I just got a new bank card and the old one should be able to be sacrificed just fine.

I did it on a Rabbit from below. Remove the pan, loosen the caps and roll them out. The only problem is when you get a peek at the crank and notice it's scored to the point of needing regrind.

Make sure you get the correct size bearings.

Dan

I did it on a TR3. No problem.

Done it several times like the others have mentioned, most recently on our Lemons car: loosen and remove the caps, then use a small screwdriver etc to pop the upper half of the bearing loose and 'roll' it out. 'Roll' the new one in the other direction.

The thing you will find is that the lower half of the bearing gets all the wear, it's very unsual to have a worn upper half unless the engine ran low on oil in which case you'd be pulling it completely apart anyway. So if the crank's in good shape but there is one upper half you can't get out, don't be concerned about it.

iceracer wrote: I once had a set of tools made for just that purpose. Basically a pin with a flat head. The pin fit in the oil hole and the flat part pushed the bearing out by turning the crank. I think they were made by Snap On. In the old days engines were overhauled with the engine in the car. Not done much anymore. I remember having the rod throw turned while the engine/crank were still in the car.

Take a cheap cotter pin (made from tin or aluminum or something softer than your block)

and bend it into a "T" shape. you want the top of the "T" to be about as thick as the bearing if not a little thinner.

You can now put the body of the "T" in the oil feed hole in the crank and when you turn the crank your home made tool will push the top half of the bearing out. Works great for tight bearings.

I hope I explained that alright, I have had good luck doing this to replace the upper bearings. On a Chrysler 2.5 the uppers were stuck to the block so a credit card would have never worked.

iceracer wrote: I once had a set of tools made for just that purpose. Basically a pin with a flat head. The pin fit in the oil hole and the flat part pushed the bearing out by turning the crank. I think they were made by Snap On. In the old days engines were overhauled with the engine in the car. Not done much anymore. I remember having the rod throw turned while the engine/crank were still in the car.

Oh yeah! Almost forgot that! My dad had throw on our '63 Chevy wagon's 327 ground next undersize (.010 IIRC) when one of the rods spun a bearing. The guy came to our home's garage with his rig and did the job in an afternoon. Seemed silly to me then, and I was about 12.

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