YACT: Spun a rod bearing, and have a couple questions

[jimbob200521]

Ok, so I spun a rod bearing on my 02 Cavalier Z24 and have a couple questions. First, should I be able to get access to replace the rod bearings by simply removing my oil pan? Or is this going to be a much bigger job than I thought? I had planned on doing this is a day, I hope that's not too unreasonable...

The next question I had is since I'm going to be replacing all the bearings with new, standard size bearings, is there anything else I should do to the car while I'll have it down like that? Or is this just a get in, replace the bearings, get out kind of job?

Any other advise/thoughts/suggestions or anything like that anyone might have for this job would be appreciated.

-Ryan

 

[boomerang]

Removing the oil pan will get you where you need to be. However, there's potential for the crank to be damaged, although you may be able to polish the journal and get by.

Also, the connecting rod is most likely toast. You may be able to remove the piston and rod assembly from the bottom, but the crankshaft may not allow you. There may not be enough clearance without removing the crank. It will be a real pain if not impossible to get that piston back in without damaging the rings.

Me, I'd prepare for the worst.

And the big question is, why did it spin a bearing? If there is an underlying cause (other than abuse) it will need to be corrected. If it's low oil level you may have a big mess on your hands. Likewise for oil pump/pressure problems.

Don't minimize the potential for big problems.

Edit: If the crank needs to be replaced, it's not coming out without the transmission coming out - from the bottom. You have to be prepared to have it towed somewhere to get it fixed. And they love getting a cardboard box full of parts.

 

[0]

how did it happen? how many miles on the motor? there's probably more to this than just one part.

 

[jimbob200521]

Originally posted by: boomerang
Removing the oil pan will get you where you need to be. However, there's potential for the crank to be damaged, although you may be able to polish the journal and get by.

Also, the connecting rod is most likely toast. You may be able to remove the piston and rod assembly from the bottom, but the crankshaft may not allow you. There may not be enough clearance without removing the crank. It will be a real pain if not impossible to get that piston back in without damaging the rings.

Me, I'd prepare for the worst.

And the big question is, why did it spin a bearing? If there is an underlying cause (other than abuse) it will need to be corrected. If it's low oil level you may have a big mess on your hands. Likewise for oil pump/pressure problems.

Don't minimize the potential for big problems.

Edit: If the crank needs to be replaced, it's not coming out without the transmission coming out - from the bottom. You have to be prepared to have it towed somewhere to get it fixed. And they love getting a cardboard box full of parts.

I've heard that spinning rod bearings (namely the #3 bearing) on the motor I have is a "common" problem (and I use that word loosely). I would like to do a more extensive repair (pull crank, check pistons, etc), but in order to do that, I would have to pull the engine which I am not able to do, so I have to do what I don't really like doing and fix the problem and move on...

 

[jimbob200521]

Originally posted by: 0
how did it happen? how many miles on the motor? there's probably more to this than just one part.

I was...driving my car with spirit when it happened...and the motor has a little over 82,000 miles on it. The oil level may have been low at the time, but when I checked the dip stick after this happened, the level looked ok.

 

[funboy6942]

Man Id say your screwed, if it in deed did spin you scuffed up and scratched the crank at that piston, putting on the same size bearing wont happen because the metal you ground off is going to make a difference. It will have to come off and get polished, then your going to have to get a new rod for that piston, or new rod and piston, and run and over sized rod bearing for that rod to make up for what the bearing did, and they took off to polish it back to new.

Id almost just say screw it, if it was me and your really set on keeping that engine, and getting a whole new crank, all new set of bearings all around, and on a safe side new piston, rings, and rod for the one that messed up. If the engine has really low miles you may want to go with new rods, pistons, and rings all around, and have the engine cylinders honed out and just do it right. But just thinking you can get away with dropping the pan, slapping in a new set of bearing, will not work because the slight amount of metal that was removed from the crank at the spun bearing is enough that it will just happen again, and with it all scratched up will chew up your new bearing in no time.

 

[Cattlegod]

Originally posted by: funboy42
Man Id say your screwed, if it in deed did spin you scuffed up and scratched the crank at that piston, putting on the same size bearing wont happen because the metal you ground off is going to make a difference. It will have to come off and get polished, then your going to have to get a new rod for that piston, or new rod and piston, and run and over sized rod bearing for that rod to make up for what the bearing did, and they took off to polish it back to new.

Id almost just say screw it, if it was me and your really set on keeping that engine, and getting a whole new crank, all new set of bearings all around, and on a safe side new piston, rings, and rod for the one that messed up. If the engine has really low miles you may want to go with new rods, pistons, and rings all around, and have the engine cylinders honed out and just do it right. But just thinking you can get away with dropping the pan, slapping in a new set of bearing, will not work because the slight amount of metal that was removed from the crank at the spun bearing is enough that it will just happen again, and with it all scratched up will chew up your new bearing in no time.

That is what I would be worried about. You will have to do a damage assessment, but your new bearing may not last long at all if something is damaged.

 

[jimbob200521]

Originally posted by: Cattlegod

Originally posted by: funboy42
Man Id say your screwed, if it in deed did spin you scuffed up and scratched the crank at that piston, putting on the same size bearing wont happen because the metal you ground off is going to make a difference. It will have to come off and get polished, then your going to have to get a new rod for that piston, or new rod and piston, and run and over sized rod bearing for that rod to make up for what the bearing did, and they took off to polish it back to new.

Id almost just say screw it, if it was me and your really set on keeping that engine, and getting a whole new crank, all new set of bearings all around, and on a safe side new piston, rings, and rod for the one that messed up. If the engine has really low miles you may want to go with new rods, pistons, and rings all around, and have the engine cylinders honed out and just do it right. But just thinking you can get away with dropping the pan, slapping in a new set of bearing, will not work because the slight amount of metal that was removed from the crank at the spun bearing is enough that it will just happen again, and with it all scratched up will chew up your new bearing in no time.

That is what I would be worried about. You will have to do a damage assessment, but your new bearing may not last long at all if something is damaged.

If there is in fact other damage, how long are we talking for a new set of bearings to last? 10 miles? 100 miles? 1000 miles?

 

[funboy6942]

If it spun a bearing, there IS DAMAGE. In order to spin a bearing it has to become smaller, or the crank has to become smaller to allow the half of the bearing to spin and lodge itself under the other half. Once that happens, it will surly grove the piss out of the crank, even if it only ran for a second or two, but the point is, something became smaller for some reason to allow it to spin, so without a doubt a new one will go, how long it will last depends on how much metal was taken off, and how badly chewed up the crank is at that point. May spin the first time it is started, you may have to measure the crank, and the new rod, and have to buy a over sized bearing for that rod, BUT if it is grooved, or scratched up, you can forget it because the bearing rides on a thin layer of oil, any groves, gouges, what ever in there will not allow the oil in there correctly and even going with a over sized bearing, it may seize up right away from lack of lubrication.

 

[jimbob200521]

Originally posted by: funboy42
If it spun a bearing, there IS DAMAGE. In order to spin a bearing it has to become smaller, or the crank has to become smaller to allow the half of the bearing to spin and lodge itself under the other half. Once that happens, it will surly grove the piss out of the crank, even if it only ran for a second or two, but the point is, something became smaller for some reason to allow it to spin, so without a doubt a new one will go, how long it will last depends on how much metal was taken off, and how badly chewed up the crank is at that point. May spin the first time it is started, you may have to measure the crank, and the new rod, and have to buy a over sized bearing for that rod, BUT if it is grooved, or scratched up, you can forget it because the bearing rides on a thin layer of oil, any groves, gouges, what ever in there will not allow the oil in there correctly and even going with a over sized bearing, it may seize up right away from lack of lubrication.

The car runs fine right now, with the exception of a "knocking" noise coming from the engine. Everyone that I have had look at it says that it's a rod bearing (2.4 DOHC). I drove the car for almost two weeks after it happened (I had no other choice, I had no other way to get to work and back) and it ran fine. The knocking noise gets louder under load, and quieter when not. At idle (~900rpm), the noise is not present.

 

[funboy6942]

Originally posted by: jimbob200521

Originally posted by: funboy42
If it spun a bearing, there IS DAMAGE. In order to spin a bearing it has to become smaller, or the crank has to become smaller to allow the half of the bearing to spin and lodge itself under the other half. Once that happens, it will surly grove the piss out of the crank, even if it only ran for a second or two, but the point is, something became smaller for some reason to allow it to spin, so without a doubt a new one will go, how long it will last depends on how much metal was taken off, and how badly chewed up the crank is at that point. May spin the first time it is started, you may have to measure the crank, and the new rod, and have to buy a over sized bearing for that rod, BUT if it is grooved, or scratched up, you can forget it because the bearing rides on a thin layer of oil, any groves, gouges, what ever in there will not allow the oil in there correctly and even going with a over sized bearing, it may seize up right away from lack of lubrication.

The car runs fine right now, with the exception of a "knocking" noise coming from the engine. Everyone that I have had look at it says that it's a rod bearing (2.4 DOHC). I drove the car for almost two weeks after it happened (I had no other choice, I had no other way to get to work and back) and it ran fine. The knocking noise gets louder under load, and quieter when not. At idle (~900rpm), the noise is not present.

OH well then you dont have a "spun" bearing, you just have a rod knock from a worn out bearing, this makes a hell of a difference then. Try not to drive the car if at all, take the pan down, do the wax gage and measure the size of the over sized bearing your going to need, and be done with it then man. Your talking spun bearing here, a spun bearing and a rod knock are two totally different animals.

While you have the pan off it may not be a bad Idea to change over the other bearings as well and gage them to and put over sized ones in, you must not of taken very good care of it, with proper oil changes, and beat the piss out of it all the time to wear out the bearings this quickly, so if the one went the others are not to far behind. Just change them all out and you should be good to go for a good while. Just be sure to measure the sizes and get the correct size, sticking in the original size may not be of much help here, just a hairs thickness will make a huge difference in how long it will last.

 

[jimbob200521]

Originally posted by: funboy42

Originally posted by: jimbob200521

Originally posted by: funboy42
If it spun a bearing, there IS DAMAGE. In order to spin a bearing it has to become smaller, or the crank has to become smaller to allow the half of the bearing to spin and lodge itself under the other half. Once that happens, it will surly grove the piss out of the crank, even if it only ran for a second or two, but the point is, something became smaller for some reason to allow it to spin, so without a doubt a new one will go, how long it will last depends on how much metal was taken off, and how badly chewed up the crank is at that point. May spin the first time it is started, you may have to measure the crank, and the new rod, and have to buy a over sized bearing for that rod, BUT if it is grooved, or scratched up, you can forget it because the bearing rides on a thin layer of oil, any groves, gouges, what ever in there will not allow the oil in there correctly and even going with a over sized bearing, it may seize up right away from lack of lubrication.

The car runs fine right now, with the exception of a "knocking" noise coming from the engine. Everyone that I have had look at it says that it's a rod bearing (2.4 DOHC). I drove the car for almost two weeks after it happened (I had no other choice, I had no other way to get to work and back) and it ran fine. The knocking noise gets louder under load, and quieter when not. At idle (~900rpm), the noise is not present.

OH well then you dont have a "spun" bearing, you just have a rod knock from a worn out bearing, this makes a hell of a difference then. Try not to drive the car if at all, take the pan down, do the wax gage and measure the size of the over sized bearing your going to need, and be done with it then man. Your talking spun bearing here, a spun bearing and a rod knock are two totally different animals.

While you have the pan off it may not be a bad Idea to change over the other bearings as well and gage them to and put over sized ones in, you must not of taken very good care of it, with proper oil changes, and beat the piss out of it all the time to wear out the bearings this quickly, so if the one went the others are not to far behind. Just change them all out and you should be good to go for a good while. Just be sure to measure the sizes and get the correct size, sticking in the original size may not be of much help here, just a hairs thickness will make a huge difference in how long it will last.

On the diagnosis end, how would one tell the difference between a spun bearing and a rod knock?

 

[funboy6942]

For starters it would knock all the time loud as hell on or off the gas, the reason your lets off a bit is because the rod is moving in the cushion of oil, its bigger and has more play since the bearing is worn out and the rod has enough room to hit the side of the block. The spun bearing would lodge itself against the other and most likely right away cause a hell of a knock then lock up the engine, or grind the hell out of the crank and making again all kinds of noise, not just louder at one point and quieter at the next.

 

[jimbob200521]

Originally posted by: funboy42
For starters it would knock all the time loud as hell on or off the gas, the reason your lets off a bit is because the rod is moving in the cushion of oil, its bigger and has more play since the bearing is worn out and the rod has enough room to hit the side of the block. The spun bearing would lodge itself against the other and most likely right away cause a hell of a knock then lock up the engine, or grind the hell out of the crank and making again all kinds of noise, not just louder at one point and quieter at the next.

Thanks for the help, man, I appreciate it

A friend and I are going out tonight to work on my car. We'll have a window of about 4ish hours to do it, so I hope we get it done. Oh, and the place I ordered my replacement bearings from only shipped me one, but considering current circumstances, I have to go ahead and replace just the one against my and others better judgment. Wish us luck!

 

[funboy6942]

good luck, will be interesting to see how long a normal size bearing will actually last. You are the only guy I know to attempt doing it, all others I know who have always used a oversized bearing.

If/when it should go out make sure you tell me please, just curious to see how long and how many miles.

 

[Christobevii3]

Purchase a rebuilt motor and put it in or just get it going and sell it.

 

[jimbob200521]

Originally posted by: funboy42
good luck, will be interesting to see how long a normal size bearing will actually last. You are the only guy I know to attempt doing it, all others I know who have always used a oversized bearing.

If/when it should go out make sure you tell me please, just curious to see how long and how many miles.

I'm not sure if that's a good thing or not :S

But yeah, I'll try and remember to let you know when (if lol) it goes out. So much for confidence on my end...

Edit: How long have you seen bearing replacements (like what I'm doing but done...more right...) last?

 

[SlowSpyder]

When I spun a rod bearing I had to get a new engine. I could of rebuilt the engine, but I would have needed a new crank or to have the damaged one machined.

 

[scorpmatt]

I've spun bearings in 2 engines.... both have crank and rod damage.

Buy a hoist, lift engine, buy a stand, put engine on stand. Tear engine down, take block to machine shop, get anally raped, take head to machine shop, raped again, put it all back together, put engine on hoist, put engine in car.

Whole process should take a week or so

 

[jemcam]

Originally posted by: Christobevii3
Purchase a rebuilt motor and put it in or just get it going and sell it.

Absolutely. Get out while you can get out cheap and trade that POS in.

 

[funboy6942]

Originally posted by: jimbob200521

Originally posted by: funboy42
good luck, will be interesting to see how long a normal size bearing will actually last. You are the only guy I know to attempt doing it, all others I know who have always used a oversized bearing.

If/when it should go out make sure you tell me please, just curious to see how long and how many miles.

I'm not sure if that's a good thing or not :S

But yeah, I'll try and remember to let you know when (if lol) it goes out. So much for confidence on my end...

Edit: How long have you seen bearing replacements (like what I'm doing but done...more right...) last?

I will be honest I have never seen anyone do it without removing the crank, getting it milled and polished, and buying the right stuff for it, when doing that, last just as long as anything else. I dont think your will last all that long due to the fact the tolerances have either gone out on the bearing side or the crank side to give it the play to make the rod knock. Without measuring to be sure, and doing it correctly, this is truly a crap shoot and very interested in the outcome. If it was the crank side that lost its size your going to end up with a rod knock after your done still, if it was the bearing that went bad, you may get lucky, provided the crank didnt get all scuffed and fvcked up chewing up your new bearing. Just be sure to take carb cleaner to every thing in there and get all the metal shaving (if any) out of there, and may not hurt while you have it out to drop a magnet in the bottom of the oil pan if there isnt one already in there, just be sure it clears the oil sump and any other moving parts., shoot thats the other thing, while you have it all apart, and if you plan on keeping it, and if this actually works, you may want to pop in a new oil pump too. They are cheap, and with 90K miles it wouldnt hurt to put in a high volume pump in.

 

[tfinch2]

I would just buy a 2.4 DOHC short block and be done with it.

Just reuse the old heads, cams, etc.

How many miles are on the car?

5 years is incredibly short amount of time to spin a bearing. You must beat the hell out of it.

 

[jimbob200521]

Originally posted by: tfinch2
I would just buy a 2.4 DOHC short block and be done with it.

Just reuse the old heads, cams, etc.

How many miles are on the car?

5 years is incredibly short amount of time to spin a bearing. You must beat the hell out of it.

Upon talking to not only funboy42, but the person who originally diagnosed it, I have given the problem the wrong wording...it's a rod knock as the result of a bearing problem. I am hoping and praying that replacing the bearing fixed my problem. If it doesn't, I honestly don't know what I'm going to do

 

[funboy6942]

Originally posted by: tfinch2
I would just buy a 2.4 DOHC short block and be done with it.

Just reuse the old heads, cams, etc.

How many miles are on the car?

5 years is incredibly short amount of time to spin a bearing. You must beat the hell out of it.

In his defense, its a Cavalier Z24, sweet car, and very fast too for what it is, if I owned it Id beat the hell out of it too. Im sure though, this has tought him a lesson to beat on it every now and then, and not all the time