oh no !!! spun bearing

[89blkvet]

I think I may have a spun bearing. I have an 89 with 75k on the stock engine. In the morning, the car starts up nice, 45 oil psi. After 3-4 minutes, the clunking begins and the oil PSI is @ 6 sitting at idle. I did drive it to the store, and of coarse the oil pressure increased with rpm, but the clunking didn't go away. If it is in fact a spun bearing, is it possible to change from below after removing the oil pan?? Thanks

 

[Jeffvette]

Stroke it.


You are doing damage to the engine by running it. There are metal pieces floating around in the oil now with a spun bearing.

Just bite the bullet and modify it some.

 

[89blkvet]

when you say "modify it", i am not sure what you mean??

 

[Jeffvette]

Go to a 383, or at minimum a 355 CI motor.

 

[89blkvet]

replace the complete engine??? why can't i just replace the lower bearings through the oil pan??

 

[DkBG]

When you spin a bearing you also damage the crank . Disreputable people might just put in a new bearing and sell the car and sometimes that can be done from below . But it ain't easy ! Cliff

 

[Magmotor]

Man I hate to hear that seeing's I've got an '89 blk/blk w/85k...wow.....that's like a doctor telling someone they've got terminal cancer....there is no fix for it except a complete rebuild or replace....that bearing is probably sitting 90 out....everytime the crank turns, it gouges a little more and puts steel dust in your oil system which will lead to more damage.....sorry too say this man but bottom line, the engine is history....:cry

 

[89blkvet]

oh man........what a drag. what causes a bearing to spin?? it looks like i will be selling car. not sure if i can aford a new engine

 

[Vettelt193]

Are you sure it is a spun bearing? It just sounds like the symptoms described could be caused by other things too.

 

[89blkvet]

no i am not sure it is a spun bearing, just assuming. what else could it be and how could i definetly find out?? I am sure i need to lower the oil pan to find out if it is a bearing???? any help would be GREAT. thanks !!!

 

[Magmotor]

Beleive it or not a bad cat sounds exactly like a bad rod...a peice breaks off inside and starts to bang around producing a loud knocking noise. Get it up on a rack with the engine running.....I'm just a little leary of your low oil pressure tho.....good luck with it....

 

[89blkvet]

you know, you are actuallt the second person who mentioned that. i will do that, but like you said, the oil pressure is on the low side??

 

[-=Jeff=-]

So I guess I will chime in an ask.. How much can you afford? Considering you said you would have to sell the car. I mean do you do your own work or would a shop have to do it?

If you can do it or even if there are members in the CAC that live near you that might be willing to help (if you lived by me I would help) and do the work yourself, meaning pullit and replace it..

As far as motor options.. you could have the short block sent to a machine shop, They could get it ready to drop back in but I would guess you will need:

Cylinders bored
New pistons since the Cylinders will be bored
New Bearings
New Timing Chain
New Oil Pump
New Main Bolts
New rod bolts
Possibly the crank turned as well

If you want to kep it semi stock, I would buy a shortblock from GM or such.. GM use to sell the ZZ4 and L98 short blocks..

That is brand new stuff, then transfer the intake, heads, and such from your current motor then drop it back in.

I don't know the prices of the short blocks but it may be very close tot he cost of the machine work.

 

[vette-dude]

Too bad you don't live closer to Richmond. I have a friend with a wrecked 88 Vette and the motor is a Jasper engine rebuild with 4,000 miles on it. The whole car can be bought for around $2,500. Engine runs perfect, Front end & suspension damage. If your engine isn't using any oil, you might skate buy with pulling it and putting in a crank kit. You would have to clean up the lifter valley and head areas to eliminate any residual metal particles but it would be cheaper than a complete O/H. Just a thought.

Randy

 

[89blkvet]

i actually live VERY close to richmond. heck, I work in san francisco and live in san leandro. I could i definetly tell if my rod bearings are bad??

 

[vette-dude]

3,000 miles away is close?? Man I know you guys in CA like to drive but we on the East coast don't consider a 3,000 mile drive as close to anything.:L :L The only way you can be sure is to eliminate all the other things. You could pull your oil filter and cut it in half, run a magnet through the pleats and see how much metal chips are in it. This will tell you if something internal has gone south. Old racer trick and it will pretty well tell you the story. Otherwise, you get to pretend your KEN and pull the engine. :eek :eek Hope you find the problem.

Randy

 

[89blkvet]

oooops, my bad. i thought you meant richmond, ca. not far from me. I am going to check the converter and if that is the noise, then possibly i have a poor operating oil pump.

 

[Jack]

Quit driving it now. Get a piece of an old bedsheet and pour the contents of oil filter through it ... take a close look at what remains on the fabric. DO cut the filter open just below seam (tin snips) .. pour any remaining oil through fabric ... then look close at-into filter's pleats. Pull the pan ... take a look ... pull off a rod cap or two ... take a look. If you've spun a rod bearing you may be able to repair & keep a lot of both your $ and reputation. If you keep running it ... it'll quickly get worse and repair/replacement bill skyrockets. Let us know what you find. Pics of damage are key to guidance.
JACK:gap

 

[89blkvet]

i will definetly stop driving it. as a matter of fact, it has been in the guarge since the noise. but help me understand that when the car is cold, there is absolutly no noise and normal oil presure. so when it gets to running temp, the oil pressure drops at idle, not running, and the noise begins. now the noise goes away while i am driving it, but at idle it re-appears. could be the cat and something else??

 

[SPANISHVETTS]

Quit driving it now.

How hard was the car driven for those 75K? A well maintained 350 just ain´t gona break with that low mileage.

Beleive it or not a bad cat sounds exactly like a bad rod

Keep an open mind; don’t blame the most expensive part. Get a stethoscope and try to pinpoint the noise.

SBC big-end bearings tend to make a lot of fuss before they give up. Even when you bore em, stroke em, & supercharge em, they usually call you and tell you they are unhappy long before they buy seersucker suits and move to Miami.

Get a piece of an old bedsheet and pour the contents of oil filter through it ... take a close look at what remains on the fabric. DO cut the filter open just below seam (tin snips) .. pour any remaining oil through fabric ...

Send the oil off to a lab if the bed sheet test doesn´t give you a good feeling.

¨spun bearing¨ is like a lot of other tech lingo. It means different things to different folks. With the Formula racing mechanics a bearing is spun when it wears to the point that one side of the shell, (bearing), can slip underneath the other side to some extent. This leaves the raw metal of the conrod banging against the crank on one side and 2 pieces of very hard bearing jammed against the crank on the other side. (Not good) If the engine does not lock up from the friction the crank and conrod will be severely damaged.

You can inspect the lower end by removing the oil pan, but forget any repairs. The C-4 engine is so easy to remove that any attempt at major repairs with the motor in place is insane.

If money, time or both are important go with a rebuilt short block. You will be back on the road in a few days for about a grand plus labor.

So I guess I will chime in an ask.. How much can you afford?

If you got more cash, U B N D right place. With me topping the list, there are lots of people here at CAC who will be happy to help you spend your $ in the evolution of your L98.