Replacing rod bearings during ring replacement

[chris90gsx]

I have been pondering this question and cannot seem to find an answer on the forums or online for that matter. I will be putting a built cylinder head on my stock block soon and am interested in replacing the rings (car has 100k miles) and possibly putting in a set of pistons and rods. If I decide to just replace the rings (along with the honing procedure) will I need to replace the rod bearings since I will be untorquing the rod to remove the piston/rod together for ring replacement? If so, won't new bearings be too perfect in shape to fit into the old rod bearing bore? From my reading of engine rebuild procedures and build up, you need to make sure the bores are perfectly round or else the bearings will not seat properly and end up seizing/spinning. This is similar to line boring the main journal bores when you do a rebuild. However, I will be doing this with the block still in the car and obviously do not want to go through the whole rebuild process as the car will only be seeing around 350-400hp max. for now. What are my options here?

 

[dls93tsi]

you pretty much have 2 options.
1. replace the rod bearings with stock bearings and hope it works o.k.
2. bite the bullet and pull the crank out to have it checked, and possibly turned down and then get matching bearings.

 

[TSIfreek]

You will have that question when you have everything apart. It just doesnt make sense to just do one thing when rebuilding the bottom end. The right and only way to do it is do it all or nothing. If you do it halfassed you will end up pulling the motor apart again because of a spun bearing. Yes I would replace all the bearings, turn the crank if it needs it, line hone, deck, bore and hone.

 

[BISHILVR]

probably NO on the turning, our cranks are hard coated and cannot be turned!!!....... (to make a long story short)

 

[dls93tsi]

Then how did the machinist manage to turn down my crank?

 

[1fast97gsx]

Then how did the machinist manage to turn down my crank?

you can do it but you will grind off the coating up top that strengthens the crank. I've heard the hardening is about .015" thick so if you only do a clean up polish you are fine ... but once you start grinding away material you will weaken the crank. 2gs have even less coating I was told.

 

[AWDlaserRS]

You could do like I did and buy a "crank kit" which is essentially a new crank with all new bearings with it. It costed me about 300 beans with the core charge.

 

[1fast97gsx]

You could do like I did and buy a "crank kit" which is essentially a new crank with all new bearings with it. It costed me about 300 beans with the core charge.

Was it a "new" crank or a regrind??

 

[alexg1323]

no regrinds, if your crank is questionable on the bearing surface see if you cant get it micropolished, or just get another used one in good condition. Alot of non turbo autos have mint ones just sitting in them, with unmolested thrust surfaces.

 

[AWDlaserRS]

Was it a "new" crank or a regrind??

Well suposedly they are all remnufactured but I measured mine and it was exactly to stock specs so either it was just polished or it was a new one.

 

[noreaga0221]

Don't re-ring it. If it aint broke, dont fix it. Now, if you did have compression in the double digits i would pull the whole block and do it the right way. I tried to just do rings and bearings and ended up pulling the block anyway since i wasn't getting the correct end gap.

 

[4pistons]

I re-ringed and re-bearinged mine with the engine still in the car after lunching a piston. (See sig picture) If the old bearings coming out are not damaged or worn then new ones shouldn't have any problem as the crank is still round and true. I had the rods resized and new bolts put in at the same time. That was three years ago.

Is this the right way to do it? No way! Having it machined and checked and trial fit is the best way to go. I've been putting engines together for a lot of years and know what's critical and what I can get away with. Your mileage may vary!

Rick - '91 GSX

 

[Eniygma]

Another quick tip:

If you rub the edge of a penny on the crank (main/rod) bearing surfaces, and the penny leaves a copper mark....crank needs to be machined.

 

[chris90gsx]

Thanks for the replies guys. I will have to budget a rebuild then. I am starting to smoke out the back and am pretty sure the 15 year old rings are on their way out. Just put new valve seals in the head so I know they are not the cause. I've smelt the burnt oil for a few weeks and noticed a cloud of smoke under acceleration today. I might go with that crank kit and new rings. Seems like a nice alternative to fully tearing out the motor and rebuilding everything.

 

[chris90gsx]

I was thinking about this earlier, why can't I just unbolt the rod caps, pull out the piston/rod, re-ring them, and then bolt them back down? Shouldn't this keep things in check without having to replace anything. That way I wouldn't have to spend all this money, which I don't have at the moment. Besides, I planned on building a block on the side anyways and this should do just fine for a daily driver.

 

[peregrine]

I was thinking about this earlier, why can't I just unbolt the rod caps, pull out the piston/rod, re-ring them, and then bolt them back down? Shouldn't this keep things in check without having to replace anything. That way I wouldn't have to spend all this money, which I don't have at the moment. Besides, I planned on building a block on the side anyways and this should do just fine for a daily driver.

youll be fine. i did this same thing a couple of years ago and i ran 12s on it all day long before i sold it. just make sure you put the right pistons back in the right bores. all this conjecture that these guys^^ are saying is for peace of mind. youll be fine.

 

[chris90gsx]

Thanks peregrine. It just doesn't make a whole lot of sense to me to get all this work done for a daily driver, but more importantly it is a money issue. Any suggestions on what rings to go with?

 

[TSIfreek]

Your turbo seals sound like they are leaking alot of oil. This will cause unknown oil cunsuption thinking its the motor and its just the turbo.

 

[peregrine]

whatever you do dont go with total seal rings. childs and albert are good. or just go with mitsu. theyre grrreat