Bearing clearance.

[Denalibro76]

Hey everyone. My apologies if this is a stupid question but I’m rebuilding my LQ4 and I’m at a roadblock concerning the main and rod bearings. I’m not building a high HP/RPM motor, just rebuilding. Can I just use stock OE replacement bearings? The old bearings looked great and the crank looks the same. I’m trying to keep this as budget friendly as I can.

 

[swathdiver]

Hey everyone. My apologies if this is a stupid question but I’m rebuilding my LQ4 and I’m at a roadblock concerning the main and rod bearings. I’m not building a high HP/RPM motor, just rebuilding. Can I just use stock OE replacement bearings? The old bearings looked great and the crank looks the same. I’m trying to keep this as budget friendly as I can.

You should be able to but I would always measure twice, use a micrometer and or plastigauge.

 

[rockola1971]

Hey everyone. My apologies if this is a stupid question but I’m rebuilding my LQ4 and I’m at a roadblock concerning the main and rod bearings. I’m not building a high HP/RPM motor, just rebuilding. Can I just use stock OE replacement bearings? The old bearings looked great and the crank looks the same. I’m trying to keep this as budget friendly as I can.

Your diameter of your bearing journals of your crankshaft determine what size bearings need to be installed. If you slap an engine together without measuring bearing clearances and using the correct bearing sizes to give the proper clearance you will find out the hard way if you guessed wrong. The engine will not last much more than 100-500 miles before the failure appears and gets louder. Or you end up with a connecting rod peeking out the side of the engine block.

A high mileage engine should have the crankshaft at a minimum polished and checked over to make sure it is in spec.

 

[Alex_M]

If the stock bearings looked great, I'd seriously consider reusing them (assuming you kept them in order).

Otherwise, you've already gotten good advice, except that I disagree about having to have your crank polished. If the bearing surfaces are all in good shape then there is no need. Plastigauge is a good tip. Time consuming, but it's one of those "buy once cry once"... You're buying peace of mind with time.

 

[Denalibro76]

If the stock bearings looked great, I'd seriously consider reusing them (assuming you kept them in order).

Otherwise, you've already gotten good advice, except that I disagree about having to have your crank polished. If the bearing surfaces are all in good shape then there is no need. Plastigauge is a good tip. Time consuming, but it's one of those "buy once cry once"... You're buying peace of mind with time.

Yes. Everything was kept in ziplock bags in order. I guess I’m not sure why I need bearings. No issues with oil pressure or anything like that before I took it apart. Zero signs of abnormal wear on the bearings and crank

 

[nonickatall]

Yes. Everything was kept in ziplock bags in order. I guess I’m not sure why I need bearings. No issues with oil pressure or anything like that before I took it apart. Zero signs of abnormal wear on the bearings and crank

It is important that you do not change the assignment of the bearing blocks to the bearings, but that the bearing blocks go back to where they were before. Unfortunately, I would still measure it with a plastic gauge to make sure they are all inside the tolerance.

 

[Denalibro76]

Ok. Yeah I’ll try and track some down and check them. Thanks

 

[rockola1971]

Ok. Yeah I’ll try and track some down and check them. Thanks

Every auto parts store in the U.S. has plastigauge.

 

[tom3]

Hate to ask but why the teardown? Just checking or a problem? I'm on the fence with reusing bearings, have to think about the "crush" that keeps them solidly in place.

 

[Denalibro76]

Hate to ask but why the teardown? Just checking or a problem? I'm on the fence with reusing bearings, have to think about the "crush" that keeps them solidly in place.

I wanted to do a rebuild due to the high mileage. It started a top end tick and using a little oil. Putting a BTR trucknorris cam, springs, lifters, trays, pushrods. So I figured I’d do it all.