Spun Bearing question?
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 7,410
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From: Little Elm TX
Spun Bearing question?
I've read a couple of posts, and now I'm wondering. Is it possible to have a spun bearing, and still have normal oil pressure? I've been told it sounds like (a diesel truck if you ask me :cry ) I've either spun a bearing or have a busted wrist pin. Either way I'm going to get it rebuilt when the funds are there to do it. I just got curious reading some posts that stated you will loose oil pressure when you have spun a bearing, and my oil pressure is the same as it was before.
Safety Car
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From: South Carolina
Re: Spun Bearing question? (R94 LT 1)
Yes it is possible and I have a trashed 96 LT1 with 58k on the clock to prove it, oil psi was normal, didn't even know I had any internal damage. Thought it was an exhaust leak. :eek:
[Modified by 96VegasVette, 8:46 PM 11/27/2001]
[Modified by 96VegasVette, 8:46 PM 11/27/2001]
Burning Brakes
Joined: Nov 2000
Posts: 1,117
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From: DFW TX
Re: Spun Bearing question? (96VegasVette)
Oh No......
I have a very slight noise like Allen's that I haven't been able to identify. Most people can't hear it. But when I use a stethascope I can hear it near cylinder 7. I have been thinking that the best way to describe it is similar to an exhaust leak, but I'm sure I dont' have a leak.
What are either of you guys other symptoms, like loss of power maybe?
Now I'm getting worried. :cry
I have a very slight noise like Allen's that I haven't been able to identify. Most people can't hear it. But when I use a stethascope I can hear it near cylinder 7. I have been thinking that the best way to describe it is similar to an exhaust leak, but I'm sure I dont' have a leak.
What are either of you guys other symptoms, like loss of power maybe?
Now I'm getting worried. :cry
Race Director
Joined: May 2001
Posts: 14,165
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Re: Spun Bearing question? (R94 LT 1)
It's usually a sound loud enough to hear without any tools. In extreme cases you can't mistake it. My friend with the camaro managed to spin 3 rod bearings and 2 main bearings. It was a nasty sound, accompanied by a nasty sounding knock. But it's a completely forged 396 now, so all is well.
Burning Brakes
Joined: Nov 2000
Posts: 1,117
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From: DFW TX
Re: Spun Bearing question? (Nathan Plemons)
Actually Nathan, I've spun a few rod bearings in my time. :D I know what it 'normally' sounds and feels like. I have always lost power soon after a bearing spun. It's just that my current noise is so hard to identify I was keeping all possiblities open for consideration.
[Modified by 92corvette, 2:51 PM 11/28/2001]
[Modified by 92corvette, 2:51 PM 11/28/2001]
Safety Car
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From: South Carolina
Re: Spun Bearing question? (92corvette)
Not trying to scare you but the Techs at the Dealership that work only on vettes missed it as well at first, I had to point it out to them, it was more noticable when you held the engine at higher RPM's. The sound was obviouse as hell to me but somehow the techs didn't hear it at first. Also I experienced no power loss, atleast none that I could feel, and the bearings were deeply grooved on mine (maines and Rods). Like I said, not trying to scare you, just telling you what happend to mine.
[Modified by 96VegasVette, 9:07 AM 11/28/2001]
[Modified by 96VegasVette, 9:07 AM 11/28/2001]
Team Owner
Joined: Mar 2001
Posts: 30,847
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From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Re: Spun Bearing question? (96VegasVette)
Does the engine shack at all?
If so then it's a bearing.
If not it might be a wrist pin.
You can drop the oil pan and check the rods on the car BTW.
If so then it's a bearing.
If not it might be a wrist pin.
You can drop the oil pan and check the rods on the car BTW.
Drifting
Joined: Aug 2000
Posts: 1,614
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From: Colleyville Texas
Re: Spun Bearing question? (R94 LT 1)
My oil pressure was okay for awhile and then would drop after the engine heated up. Eventually would loose power at idle. Helped me justify that the 396 was a rebuild and not a mod. :)
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Drifting
Joined: Mar 1999
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From: Norcross GA
Re: Spun Bearing question? (BrianCunningham)
Did you pull the Vcover to have a look?
No sure what you are looking for. Either way you are looking at a rebuild. If you continue to drive it w/ a spun bearing or a broken wrist pin, you will eventually grenade the whole thing. If you break it down now, you can save many of the pieces.
No sure what you are looking for. Either way you are looking at a rebuild. If you continue to drive it w/ a spun bearing or a broken wrist pin, you will eventually grenade the whole thing. If you break it down now, you can save many of the pieces.
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 7,410
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From: Little Elm TX
Re: Spun Bearing question? (ZylaRace)
Trust me, as soon as it started, I stopped driving it. It will sit till I have the money to fix it. I just thought it was strange that I didn't loose oil pressure. I start it about once a month, just to keep the battery charged. (apartment, no garage) It sounds fine at idle, just a little knock, but under any load, it sounds just like a diesel. :cry Since it's high mileage, I won't chance it anymore than I have to and like it was said, either way it would have to be rebuilt. Only reason I haven't gone through the trouble to pull the pan.
Safety Car
Joined: Mar 2000
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From: Hillsboro OR
Re: Spun Bearing question? (R94 LT 1)
Bad Rod bearings usually make noise when you are declerating. Bad Main bearings make noise when you under load. A wrist pins could have come loose but I doubt you broke one. They are pretty beefy. Loose wrist pins make a double knock sound.
Drain your oil. You'll find lots of metal in it if you've spun something.
Drain your oil. You'll find lots of metal in it if you've spun something.
Safety Car
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From: South Carolina
Re: Spun Bearing question? (AquaMetallic94LT1)
Bad Rod bearings usually make noise when you are declerating.
Drain your oil. You'll find lots of metal in it if you've spun something.
Drain your oil. You'll find lots of metal in it if you've spun something.
Exactly right, that is where I had the most noise on rapid deceleration, I had to snap the throttle and let off quick to get the GM techs to catch what I heard so clearly, The click associated with the deceleration is what had me thinking is was a heatriser. It also clicked actually ticked is a better description...at idle and all other speeds but was more pronounced on decel and at a certain RPM range.
Edit: And yes my oil was filthy.
[Modified by 96VegasVette, 9:11 PM 11/28/2001]
Pro
Joined: Nov 1999
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From: Woodland Ca
Re: Spun Bearing question? (AquaMetallic94LT1)
When you drop the oil pan, what are you looking for other than a lot of metal flakes? If you open the valve covers what would I be looking for?
I understand that if you find a spun main that would help me know which valve cover to open to look for damage on the top of the motor.
Would you do one of the tests above or would you first check each cylinder at a time by unpluging a spark plug at a time while the engine is running to see if the noise stops?
Would this cause more damage to the motor?
Yes ,I finally got the time and the money in place to fix my car and am try to figure out the best way to go about it.
Thanks
I understand that if you find a spun main that would help me know which valve cover to open to look for damage on the top of the motor.
Would you do one of the tests above or would you first check each cylinder at a time by unpluging a spark plug at a time while the engine is running to see if the noise stops?
Would this cause more damage to the motor?
Yes ,I finally got the time and the money in place to fix my car and am try to figure out the best way to go about it.
Thanks
Burning Brakes
Joined: Nov 2000
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Re: Spun Bearing question? (BIG K)
Pulling the plug wires while running can help determine if its a spun rod bearing, but if its spun then everytime you start the car you risk further damaging the engine. I pulled the oil pan on mine when I thought I spun a rod bearing, as it turned out it was two bearings (7 & 8 ), I was lucky and was able to have the crank turned, but had I continued to run the engine I'm sure I would have bought a new crank. Then again if the crank is ruined you can justify a stroker crank (383 or 396). :yesnod:
