Main Bearing Question

[CajunKenny]

The engine is still in the car. I have the pan off and have changed all the rod bearings so far. I'll be pulling the main caps tomorrow to inspect them.

Can or has anyone successfully changed out the main bearings without removing the crank? If so...how?

I have one idea and that is to sort of feed the new one in place while pushing the old one out. Does that make sense? Does that sound like a good idea?

 

[Rennat]

I do not believe that can be done... because the crank is held in place with the front case, and the rear main seal... you COULD try pushing them out of the side, but i dont think it will work...

Are you just trying to fix rod knock? or what?

 

[CajunKenny]

Yep, it has/had a rod knock. Most of the rod bearings were badly worn. No copper showing; but, almost there. The crank has inspected 'OK' so far. Now I'm down to the mains.

 

[Rennat]

The mains "should" be ok if it was rod knock.... just make sure you clean everything REALLY good when you have it apart, and when you put it back together...

Any reason you just didnt pull the engine and rebuild it?

 

[CajunKenny]

I have one on the stand that is going to the machine shop soon. I just decided (with the help of a friend off this forum) to pull the pan on my existing motor to see how bad the damage was.

After we did that, I just decided to throw a set of bearings at it and put it back on the road till my second engine is done.

I'll admit it man! I'm going through Supra Withdrawels!!! :cry:

 

[noredline]

I'll admit it man! I'm going through Supra Withdrawels!!! :cry:

Don't we all.....it's a love/hate seeing another MKIII on the road when others are sitting patiently waiting to be rebuilt.

 

[Doward]

NO NO NO

DO NOT JUST REPLACE THE BEARINGS AND HOPE KNOCK GOES AWAY

Your engine started knocking for a reason - FIX THAT FIRST.

Which rod started knocking? Get it re-conditioned.

Seriously. Do it right, or don't bother doing it at all.

 

[CajunKenny]

The guy I got the car from ran it with low oil. It was like 2-1/2 quarts low when i got it! That's when the knock started. I'm just trying to limp this engine along until my other one is done.

I'm sure the top end is bad also; but, throwing bearings at it should get it back on the road. Bearings are cheap so I thought "What the hey!"

I'm glad that I rescued her out of the hands of someone who was mis-treating her. I've already given her the TLC of getting little odds and ends fixed. She'll have a new engine by March.

I'm sure she'll be greatful and treat me very well. I see a great relationship in the works.:biglaugh:

 

[NewWestSupras]

Dream on. She'll show you a little leg, take all your money, then ask for more.

 

[supra_kid101]

NO NO NO

DO NOT JUST REPLACE THE BEARINGS AND HOPE KNOCK GOES AWAY

Your engine started knocking for a reason - FIX THAT FIRST.

Which rod started knocking? Get it re-conditioned.

Seriously. Do it right, or don't bother doing it at all.

110% Correct!!! If it was low on oil did you change it and see if the knock went away? Theres going to be small scratches on the journals you can't see that will kill the engine in about a week. Don't waste a good engine by skipping steps please.

 

[CajunKenny]

I have one on the stand that is going to the machine shop soon. I just decided (with the help of a friend off this forum) to pull the pan on my existing motor to see how bad the damage was.

After we did that, I just decided to throw a set of bearings at it and put it back on the road till my second engine is done.

I'll admit it man! I'm going through Supra Withdrawels!!! :cry:

Ok. You guys are busting my chops here! :aigo:

I have a second engine that I'm building the 'RIGHT' way!

This one was run low on oil which resulted in a rod knock. The bearings show considerable wear (114k); but, no grooves or copper showing. Cylinders 2 and 4 were knocking. The crank seems 'ok' for what I'm doing. The oil pick-up screen doesn't have any debris stuck on it and there are no chunks in the bottom of the pan.

I just want to see if I can change out the mains without pulling the crank because the engine is still in the car.

I'm just 'limping' this one along till my other one is done! :icon_bigg

 

[supra_kid101]

The mains cannot be changed by leaving the crank in. It has to be pulled to get the ones off the block. Like I previously said it'll die in a week or so trust me I tried it a year ago. We all have Supra withdrawels at times but honestly you should put out and wait for the other engine rather than waste your money on new bearings to just have to replace them again very very soon. It's just my .02 but surely you can see my point of view I hope.

 

[CajunKenny]

Is that what happened to yours...was it run low on oil? How long did it last after the rebuild (patch job)?

Don't get me wrong, I agree with what you're saying and see your point. I just happen to have a cheap set of bearings (rock products) laying around and thought I'd gamble a little bit. :naughty:

Can't blame a guy for that can ya? :biglaugh:

 

[Nomad707]

Is that what happened to yours...was it run low on oil? How long did it last after the rebuild (patch job)?

Don't get me wrong, I agree with what you're saying and see your point. I just happen to have a cheap set of bearings (rock products) laying around and thought I'd gamble a little bit. :naughty:

Can't blame a guy for that can ya? :biglaugh:

this isnt gambling, its stupidity.. no offense... you will ruin your engine that is fixable just because you are impatient... fix it right!!!

 

[supra_kid101]

Is that what happened to yours...was it run low on oil? How long did it last after the rebuild (patch job)?

Don't get me wrong, I agree with what you're saying and see your point. I just happen to have a cheap set of bearings (rock products) laying around and thought I'd gamble a little bit. :naughty:

Can't blame a guy for that can ya? :biglaugh:

Heres my sad story lol:
Bought my first supra and had no clue about the 7M oiling issue. Developed a knock due to 2 quarts low on oil. Turned out to be the #1 cylinder. I changed the rod bearings and changed the oil. 6 days later the knock came back with a vengence. The rod banged around in there for a few seconds sending the rod cap through the side of the block effectively making my engine useless in a matter of a few seconds. 4 in. hole in the bastard. I'll try to find pics of it if I can to show you.

I understand that it's nature to experiment. I've got GE internals in my GTE running 12psi right now lol. Very very fun car haha.

The tolerences are so tight on these cars you can't just gamble with it.

Just trying to help you learn from my mistake dude.

 

[CajunKenny]

this isnt gambling, its stupidity.. no offense... you will ruin your engine that is fixable just because you are impatient... fix it right!!!

None taken.

I'll still do it and see what happens. If it blows up the next day. So be it. I'll give all of y'all kudos. BUT!!! If not, I'll expect the stupidity statements retracted.:naughty:

Ultimately, it's a gamble. And it's MY gamble. In the end, "stupidity" or not, We'll ALL learn form it and that's what this forum is all about!

 

[CajunKenny]

Heres my sad story lol:
Bought my first supra and had no clue about the 7M oiling issue. Developed a knock due to 2 quarts low on oil. Turned out to be the #1 cylinder. I changed the rod bearings and changed the oil. 6 days later the knock came back with a vengence. The rod banged around in there for a few seconds sending the rod cap through the side of the block effectively making my engine useless in a matter of a few seconds. 4 in. hole in the bastard. I'll try to find pics of it if I can to show you.

I understand that it's nature to experiment. I've got GE internals in my GTE running 12psi right now lol. Very very fun car haha.

The tolerences are so tight on these cars you can't just gamble with it.

Just trying to help you learn from my mistake dude.

That is a sad story. Thanks for sharing.

Good luck with the 7M internals. That reminded me of something! I might have access to a downed 7M. Are you running 7M cams too?

 

[supra_kid101]

Amazing.....so many people stating what a stupid idea it is yet you still continue on with it. You'll learn someday. Hopefully you'll take better care of your new engine than this one hopefully.

Yea GE cams. My mods are:
GE rods, GE pistons, GE cams, GE cylinder head (the GTE one was cracked), GTE everything else. 3" turbo back exhaust, intake, shimmed wastegate to 12psi, Q45 fuel pump, 2mm MHG, ARP headstuds. Quick little car aside from boost leak. Getting 1GGTE style hardpiping with a FMIC in a few days.

 

[CajunKenny]

You must have missed it above. I got the car this way. Only two people think it's a bad idea so far and only one of them speaks from experience.

Your ride sounds sweet.

Keep the rubber side down man...

 

[IJ.]

The mains cannot be changed by leaving the crank in. It has to be pulled to get the ones off the block. Like I previously said it'll die in a week or so trust me I tried it a year ago. We all have Supra withdrawels at times but honestly you should put out and wait for the other engine rather than waste your money on new bearings to just have to replace them again very very soon. It's just my .02 but surely you can see my point of view I hope.

You really need to NOT post incorrect imformation....
If you don't know don't post it as fact.

Can the Mains be changed with the crank in the Motor? YES

Should they be changed like this? NO