Possible spun bearing...
Cruising
Joined: Dec 2004
Posts: 14
Likes: 0
From: Edmond Oklahoma
Originally Posted by 89 Paul in Cal
Does the sound speed up or slow down along with the RPM's?
Crankshaft speed or camshaft speed?
(the crank revs twice as fast as the cam)
Crankshaft speed or camshaft speed?
(the crank revs twice as fast as the cam)
Safety Car
Joined: Sep 2004
Posts: 4,824
Likes: 0
From: Port Orange Florida
Well seems that your oil pressure gauge works so I will go with bad bearings seeing that it hits zero at idle warm.That's bad.I bet the motor makes some rattling noise also when the oil preassure drops.
It doesn't sound like you spun a bearing.Sounds like they are outta limits.If you spun a bearing it wouold have terrible oil pressure all the time.
I wouldn't even start it anymore.Those mains need to be looked at first.
It doesn't sound like you spun a bearing.Sounds like they are outta limits.If you spun a bearing it wouold have terrible oil pressure all the time.
I wouldn't even start it anymore.Those mains need to be looked at first.
Advanced
Joined: Jul 2004
Posts: 80
Likes: 0
I agree with kittmaster: A worn throwout bearing will sometimes make noise with the clutch pedal out, but can quiet down when it's pressed against the pressure plate (pedal in). I'm no expert, but a spun bearing (either rod or crank) should make some terrible noise under all conditions and will eventually sieze. You could retain oil pressure if the bearing has spun itself over the oil holes, but then there will be no oil to the journals -> heat -> failure -> quick! Bet it's not a spun bearing.
Cruising
Joined: Dec 2004
Posts: 14
Likes: 0
From: Edmond Oklahoma
Originally Posted by Shoregasm
Well seems that your oil pressure gauge works so I will go with bad bearings seeing that it hits zero at idle warm.That's bad.I bet the motor makes some rattling noise also when the oil preassure drops.
It doesn't sound like you spun a bearing.Sounds like they are outta limits.If you spun a bearing it wouold have terrible oil pressure all the time.
I wouldn't even start it anymore.Those mains need to be looked at first.
It doesn't sound like you spun a bearing.Sounds like they are outta limits.If you spun a bearing it wouold have terrible oil pressure all the time.
I wouldn't even start it anymore.Those mains need to be looked at first.
If so, will this require a rebuild?
Pro
Joined: Aug 2000
Posts: 700
Likes: 1
From: Florida
Sorry to say but it sounds like a spun bearing. Drop the oil pan and see if you see metal fragments. When my # 1 bearing spun my oil pressure dropped. Classic indicator. If you do rebuild, put in a new oil pump and weld the pickup unit. Not sure what it is with these LT1's. Perhaps it's an oil starvation issue or inadequate bearing clearance that occurs with age. Make sure you use ARP bolts
Hank
Hank
Burning Brakes
Joined: Aug 2000
Posts: 984
Likes: 1
From: Cincinnati OH
Originally Posted by phxscooby101
About 20 min later I start her up and it whines intermidately not a constant, and the idle is iradic with some knock I THINK.
Also it sounds like it's coming from the passenger side more.
Car: 1992 with 29k 6 speed
Also it sounds like it's coming from the passenger side more.
Car: 1992 with 29k 6 speed
1992's had a problem with "fuel line hammer", which sounds like a knocking sound coming from the passenger side of the engine compartment. You can hear the knocking from inside the car while idling. If you have a stethoscope (or hose or whatever), check if the knock is coming from the fuel line accumulator, a silver disk shaped canister on the fuel line on the passenger side of the engine compartment. That may be what you are hearing. I believe GM's fix was to isolate the fuel lines better, but I do not know the details.
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Advanced
Joined: Jul 2004
Posts: 80
Likes: 0
I rebuilt the 327 in my 67 Chevy II awhile ago and had extemely low oil pressure (but no knock) after startup (<5 psi). After weeks of searching and testing, I took the engine apart and found nothing visibly wrong - until I started to reassemble it. I then found I had stretched the main bearing bolts significantly and couldn't make the required torque. If you find that you didin't spin a bearing after all, you might check whether the rebuilder used new bolts on the bottom end - good luck.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 108
Likes: 0
Alright I started her up one more time when it was cold, The whine noise is gone but kinck and klanck is there off and on not constant.
So I am thinking I
1.bent a rod
2.lost a valve and it is getting smashed on the cylinder
3.something in the head let go
I have very good oil pressure 75 on start up and stayed there.
So how hard is it to pull the heads on these LT1's?
If there are know signs of damage to the heads I know it will be a spun bearing then I will pull the motor. I have the GM books on the car, so pulling the motor doesn't look too difficult.
What are my options?
1.Rebuild current setup but all forged internals.
2.Crate engine with forged internals( not sure what is available).
3.The car has to be able to pass AZ emissions.
4.The current block has me worried because previous owner had the rebuild done because of spun bearing, so maybe the block is warped??
Money keep it around 6k
I would like hear everyone's opinion on the matter.
Thanks Chad
So I am thinking I
1.bent a rod
2.lost a valve and it is getting smashed on the cylinder
3.something in the head let go
I have very good oil pressure 75 on start up and stayed there.
So how hard is it to pull the heads on these LT1's?
If there are know signs of damage to the heads I know it will be a spun bearing then I will pull the motor. I have the GM books on the car, so pulling the motor doesn't look too difficult.
What are my options?
1.Rebuild current setup but all forged internals.
2.Crate engine with forged internals( not sure what is available).
3.The car has to be able to pass AZ emissions.
4.The current block has me worried because previous owner had the rebuild done because of spun bearing, so maybe the block is warped??
Money keep it around 6k
I would like hear everyone's opinion on the matter.
Thanks Chad
Instructor
Joined: Jan 2003
Posts: 182
Likes: 0
From: Newberry SC
what you are describing is throwout bearing noise.
1. bent rod.....rods just don't bend for no apparent reason, most common reason is hydro lock....so no
2. if lost a valve in the cylinder you would have MUCH worse problems....so no
3. what would you be suggesting let go? a spring could break and i have seen if before where it would make noise, but the engine would also skip and run like crap, and more than likely drop a valve.
your oil pressure is good, the engine apparently performs ok, have you tried pressing the clutch in and observing what happens?
honestly, i have been around engines a good bit, cars in general for that matter. what you are describing does not sound like a spun bearing.....take it for what its worth, but i think you are making a big deal out of nothing really...
good luck
1. bent rod.....rods just don't bend for no apparent reason, most common reason is hydro lock....so no
2. if lost a valve in the cylinder you would have MUCH worse problems....so no
3. what would you be suggesting let go? a spring could break and i have seen if before where it would make noise, but the engine would also skip and run like crap, and more than likely drop a valve.
your oil pressure is good, the engine apparently performs ok, have you tried pressing the clutch in and observing what happens?
honestly, i have been around engines a good bit, cars in general for that matter. what you are describing does not sound like a spun bearing.....take it for what its worth, but i think you are making a big deal out of nothing really...
good luck
Last edited by clemsonvette; Dec 30, 2004 at 12:23 AM.
Drifting
Joined: Feb 2004
Posts: 1,485
Likes: 2
From: Champaign, IL
St. Jude Donor '05
After having my engine spin a bearing twice in the last six months I have to say that it sounds like that is what has happened to your engine.
When the motor is cold it won't be as bad, but as soon as it warms up it's terrible. Don't run the motor anymore get the car to a machine shop or a good mechanic. Pretty soon the metal from the bearing will be all over the place inside your motor and you'll have metal on metal squealing noises if you don't already.
I had good oil pressure on my engine both times - the first time it happened (rod bearing) it was with 1 mile on the engine after a full top end rebuild. The second time it happened (main bearing?) was with 400 miles on my fresh 355.
When the motor is cold it won't be as bad, but as soon as it warms up it's terrible. Don't run the motor anymore get the car to a machine shop or a good mechanic. Pretty soon the metal from the bearing will be all over the place inside your motor and you'll have metal on metal squealing noises if you don't already.
I had good oil pressure on my engine both times - the first time it happened (rod bearing) it was with 1 mile on the engine after a full top end rebuild. The second time it happened (main bearing?) was with 400 miles on my fresh 355.
Drifting
Joined: Feb 2004
Posts: 1,485
Likes: 2
From: Champaign, IL
St. Jude Donor '05
Stopped by the shop today. .. they got my motor pulled apart this morning and it was a rod bearing again this time.. sucks but I guess that's better than a main bearing.
Keep us posted on your car Chad!
Keep us posted on your car Chad!
Pro
Joined: Aug 2000
Posts: 700
Likes: 1
From: Florida
Originally Posted by ToyC4
Stopped by the shop today. .. they got my motor pulled apart this morning and it was a rod bearing again this time.. sucks but I guess that's better than a main bearing.
Keep us posted on your car Chad!
Keep us posted on your car Chad!
Who's working on your engine? What's with the spun bearings?
Drifting
Joined: Feb 2004
Posts: 1,485
Likes: 2
From: Champaign, IL
St. Jude Donor '05
Originally Posted by 93LT1
Toy04
Who's working on your engine? What's with the spun bearings?
Who's working on your engine? What's with the spun bearings?
Thread Starter
Instructor
Joined: Dec 2004
Posts: 108
Likes: 0
Well I pulled the valve covers and nothing visably wrong springs, roller rockers and rods look great, so now I am going to record the sound and post it on here for everyone to hear.
Please give your opinions.
Thanks, Chad
Please give your opinions.
Thanks, Chad
