What is a thrust bearing and how do you tell if it's bad?

[kna4977]

I'm looking at buying a TR, and the seller mentioned something about a thrust bearing. I'm not familiar with this. I've been trying to find pictures on the web of a thrust bearing, but I'm not really turning up anything that is beneficial. If someone has a diagram or picture that shows where it is, that would be great. Also, is there a way to tell if one is bad? What are the symptoms? What is involved as far as labor and dollars to replace one? I can't really find any specifics on this either. thanks

 

[puddinpower]

The thrust bearing is the middle main bearing on the crank. Need less to say the motor would have to come out and rebuilt.One way to check it would to be to see how much end play you have in the crank.That means see how much the crank will move back and forth from front to back.If it is alot which you will be able to see then it is gone. Most people have there crank end play set at 6 to 9 thousanths.And that is an average. When the car is running,have some one rev the motor up while you are looking at the balancer.See if you can see the balancer move out towards the radiator. If it is bad you would here a knock in the motor.It is a deeper knock sound then what a rod bearing knock would be.

HTH

Puddin

 

[kna4977]

Where is the thrust bearing located in the turbo regal. Is it in the front, middle or rear of the engine, and is there a way to inspect it to see if that's what the problem is?

 

[SouthernCal GN]

As stated above- the center main bearing is the thrust. You hve to pull the pan to see it.

What problem does the seller mention (specifically)?

 

[carlsbadGN]

As I recall, the thrust bearing was replaced in my first GN without pulling the engine. We were doing the rear main seal and the bearing was knocking at the time.

 

[Jerryl]

The $1,00,00 question is;
"What made it go bad"?

 

[fc227]

As I recall, the thrust bearing was replaced in my first GN without pulling the engine. We were doing the rear main seal and the bearing was knocking at the time.

How did you do this? Did you loosen all the main caps? And then slide the upper part of the thrust bearing out?
How did you get the new one in?

 

[SouthernCal GN]

As I recall, the thrust bearing was replaced in my first GN without pulling the engine. We were doing the rear main seal and the bearing was knocking at the time.

Bearings don't knock...........they spin. Rods knock. Not trying to bust yer balls, but good info, not sympathetic info, keeps all of us ahead of the curve.....

 

[bison]

The #2 main (2nd one rearward of the 4) is the thrust main. If it failed simply replacing it wont usually solve the problem and it will fail again. It will send metal shavings throughout the engine and usually ruin the thrust surface on the crank if run long enough. If the torque converter pressure is over 40 psi (some say up to 60 psi is ok) then the converter will be thrust excessively hard toward the bearing and it will overheat and fail. The root cause must be found to prevent further failures. Plan on $1000 minimum to find the problem and fix all the damage it caused. It cant be fixed correctly in the car since the metal shavings cant be removed from the engine. It needs a complete tear down.

 

[carlsbadGN]

Sorry for the dorky post, I should have typed what I was thinking. When I had my first GN in the early 90's, Mike Doyle (Mike Doyle Transmission Service, Cucamonga, CA) did some of the mechanical repairs. I took the car to him in 1993 to fix a few problems, among which was a knock in the engine.

Mike diagnosed the knock as a bad thrust bearing. I don't remember if he fixed it that day or if he had to order the bearing. Anyway, he did eventually lift the car and fixed it from under neath. As a note of interest, he charged $90.00 to do the job, plus $14.20 for the thrust bearing, $15.64 for the pan gasket, and $12.00 for the oil.

I do vaguely recall looking at the old bearing but he didn't want customers in the shop area so I didn't get to see what he was doing. At the time, he did good work and I had no doubt he knew what he was doing.

I kept the car for two more years as a daily driver and had no more problems with the engine knocking.

 

[JayC]

If the thrust has been damaged for a while, the crank may need to be replaced/fixed.

 

[my1stgn]

Bearings don't knock...........they spin. Rods knock. Not trying to bust yer balls, but good info, not sympathetic info, keeps all of us ahead of the curve.....

I dont think that the bearing on the crankshaft is supposed to spin,..... correct me if Im wrong but this would be a "spun bearing" if that happened then you would hear a whole lot of noise coming from that part of the engine:biggrin: "Not trying to bust yer balls, but good info, not sympathetic info, keeps all of us ahead of the curve"

 

[SouthernCal GN]

I dont think that the bearing on the crankshaft is supposed to spin,..... correct me if Im wrong but this would be a "spun bearing" if that happened then you would hear a whole lot of noise coming from that part of the engine:biggrin: "Not trying to bust yer balls, but good info, not sympathetic info, keeps all of us ahead of the curve"

Yeah, I is a dork! Meant to type "bad bearings don't knock- they spin"

go ahead, bust 'em, I deserve it:biggrin:

 

[puddinpower]

Yeah, I is a dork! Meant to type "bad bearings don't knock- they spin"

go ahead, bust 'em, I deserve it:biggrin:

After the bearing spins then what happens??? you hear KNOCK !!!!!!
If not you would not know that the thrust bearing or any bearing for that matter was bad.
I'm i wrong?

 

[SouthernCal GN]

After the bearing spins then what happens??? you hear KNOCK !!!!!!
If not you would not know that the thrust bearing or any bearing for that matter was bad.
I'm i wrong?

Puddin, if you read the reference posts, you'll see where it was mentioned that a bearing was knocking........bearings don't knock.

#1 main spun on my last engine, and there was no knock....

 

[turbofabricator]

I heard the knock, and answered my front door...........No bearing was there?

What are you guys talking about?

You CAN replace the crank and bearings with the engine in the car. HOWEVER!!!!! the debris (as stated previously) are probably still in there. If the bearing is toast, then you will also NEED to replace the oil cooler in the radiator, or run with out the oil cooler. If you skip this step, your will soon need to redo the bearings. Time to pull the engine and do the job right. Pay close attention to the oil cooler suggestion, too.

 

[puddinpower]

Puddin, if you read the reference posts, you'll see where it was mentioned that a bearing was knocking........bearings don't knock.

#1 main spun on my last engine, and there was no knock....

I know that the bearing it self does not knock thats a no brainer.his question was where and how to tell if it is bad and what IS the thrust bearing.
Out of all of the motors that i have messed with in the turbo buicks that has had thrust bearing problems ( been working on these motors since 1985 ) all have had a knock after the thrust bearing wears out on the front and rear sides of the bearing.If the the question was how can you tell that #1#3,or the rear main was bad i would have had a different answer like does it have some oil press problems etc.etc.I miss spoke on the rod BEARING knock in my first post.I should have said just a deeper knocking sound not like a rod knock!!
Sorry for the confusion.carry on

 

[fc227]

If the thrust has been damaged for a while, the crank may need to be replaced/fixed.

That’s why I was asking about replacing it in the car. It would be hard to get a real accurate measurement of the cranks thrust-bearing surface. Other than a visual and checking for grooves on the thrust surface.

 

[kna4977]

Okay, I thought I would get an e-mail each time someone posted on this thread, but that hasn't happened. I have the car in my garage. I pulled the oilpan to see what was up. I don't see any thing out of the ordinary, but I don't really know what I am looking for. There are a few gold shavings on the surface of the oilpan and a few on the screen of the oil pump. I've done a few fluid changes, and that doesn't seem to be out of the ordinary, but I don't know. At this point the car knocks slightly at idle when at operating temp, but if you rev it slightly it goes away and does not do it if it is in gear at any temperature. If you turn the idle up slightly, you hear no more knock, but I'm sure that is probably only a temporary solution. The question at this point is if I have pulled the pan, what am I looking for to diagnose a bad thrust bearing, and is there really any way to tell? Also, I should add that when listening underneath the car the knock seems sort of shallow and localized to the transmission/engine connection area, and the 3 bolts that connect the 2 together seem fine.

 

[bison]

At this point i would remove the number #2 main cap and inspect the thrust bearing. Shavings are bad. You need to find the cause off the shavings. The low rpm knock could be piston slap and not a rod knock. Rod knocks usually get worse with more rpm.