Toasted thrust bearing..need advise

[Black Demon]

Found some glittering bearing material in oil last week. Uh-Oh..decide to pull oil pan this morning and found my thrust bearing is down to copper on both sides. Looks like some heat build up has occured also from the looks of the discolored bearing. Bearing does not look good..scratches and pitting in the material. Crankshaft is not bad..Polishing will probably clean it up.

First thought was lousy machine work. Engine has 7000 miles since it was rebuilt ( wiped lobe on cam after wrong valve springs were put in by a "well-known" mechanic). Crank was turned and the rotating assembly was balanced.

Any thoughts anyone? With both sides of the thrust bearing down to copper I am thinking the clearances were never right to start with. Car has not been roughed up with only two trips to the track in 2 years. Mainly used as a pleasure ride.

Mike

 

[KWIKR 1]

Mike do a search on that topic . Lots of info to get you started . I'm just had the same thing happen . Only mine lasted 15 mins . There is a list member (Sean) who owns a GN and is involved with Federal Mogul bearing engineering division . Who has a ton of very useful info in his head . It maybe a good idea for Sean to post his info on this topic . This topic seems to be coming up more often than not lately .

 

[Black Demon]

Thanks for the reply KWIKR 1. After taking a long look at the bearing it looks as if the crank was pushed foward and ate into the sides of the bearing. Got to hook up a pressure guage to the tranny after the short block is rebuilt. This will give me a chance to rebuild the engine the way it should have been built to start with!

Mike

 

[turbojimmy]

Originally posted by Black Demon
Thanks for the reply KWIKR 1. After taking a long look at the bearing it looks as if the crank was pushed foward and ate into the sides of the bearing. Got to hook up a pressure guage to the tranny after the short block is rebuilt. This will give me a chance to rebuild the engine the way it should have been built to start with!

Mike

Welcome to the club!!! My 2,500-mile engine is coming out this week because of the same problem. I didn't have (or notice anyway) metal in the oil. Instead, it started knocking and I could SEE the crank pulley moving back and forth as it idled.

The guy that did the engine has been doing it for a long time and most of his experience is with these V6s. I don't think it was something he did. I posted some questions a week or two ago on the gnttype mailing list. There was A LOT of discussion/debate over what causes this. Bottom line is that there is no cut and dry answer, but a lot of it points back to the only thing that can be applying pressure to the back of the crank - the torque converter. There are plenty of well-known, well-respected experts that say the TC couldn't really cause this kind of damage. Who knows?

The machine shop that has my engine (the whole car actually) is doing their own investigation. I'll post back if they find anything interesting.

Jim

 

[KWIKR 1]

I got my TC checked out right after . And it checked out 100% . Mine looked like it could of been a combination of crankshaft thrust face finish and a thrust cap issue . turbojimmy , did you have billet caps on the block ?

 

[turbojimmy]

Originally posted by KWIKR 1
I got my TC checked out right after . And it checked out 100% . Mine looked like it could of been a combination of crankshaft thrust face finish and a thrust cap issue . turbojimmy , did you have billet caps on the block ?

Yes, billet caps on the new engine. And, I had my TC cut apart, rebuilt and the run-out checked out after the original engine failed thrust and #3 and #5 mains were toast. I didn't realize until later on that it was a lateral motion that wiped them out. Check out my bearings here: http://jimmyz.tzo.com:231/GN_Engine_Pull/042702-05.JPG. See the sides of the bearings torn off.

Anyhow, back to this new engine. Based on the motion of the balancer, the engine guy said I'd at least need a new crank. I'll probably find out what the damage is - and what caused it - later this week when he gets the engine out of the car.

Jim

 

[KWIKR 1]

IMO , I say these engines are VERY VERY line bore/billet cap sensitive . you have to make sure that the person doing the machine work is on top of his game .

 

[turbojimmy]

Originally posted by KWIKR 1
IMO , I say these engines are VERY VERY line bore/billet cap sensitive . you have to make sure that the person doing the machine work is on top of his game .

This guy is good. He's done A LOT of them and has been doing them nearly as long as I've been alive. I talked to some folks that have his engines, all seem happy. I really got burned on my trans so I didn't want to make the same mistake with the engine. It's not totally out of the realm of possibility that he did something wrong - no one is infallible - but I trust him enough to make good on it if that's the case. I think things may be pointing back to the converter - it all went downhill after my Level10 trans rebuild.

Jim

 

[Black Demon]

Jim,

Know what you mean about the machinist. The shop that did this engine has done quite a few in the Ga/Carolina area with no problems. When I bought the car it was in the hands of an Atlanta mechanic that could not supply me with any paperwork that I asked for (he shall remain nameless-unless I get a PM). Anyway the engine will be coming out this weekend and I have a few things to look for. Also I will be taking it to the machine shop and asking how it happened. Chuck Leeper gave me some good ideas on the phone today about this. I'll post what I find out.

Mike

 

[turbojimmy]

Originally posted by Black Demon
Jim,

Know what you mean about the machinist. The shop that did this engine has done quite a few in the Ga/Carolina area with no problems. When I bought the car it was in the hands of an Atlanta mechanic that could not supply me with any paperwork that I asked for (he shall remain nameless-unless I get a PM). Anyway the engine will be coming out this weekend and I have a few things to look for. Also I will be taking it to the machine shop and asking how it happened. Chuck Leeper gave me some good ideas on the phone today about this. I'll post what I find out.

Mike

This guy wanted me to bring him the whole thing. He was really cool about it. He's going to do the autopsy and fix it up again. I drove it down there last week. He says it'll be done in a few weeks. I'll post as much of a post-mortem as I can get.

Jim

 

[BobbyBuick]

you can buy an oversized thrust surface bearing in 10-20- and40 over
Im getting too good at it

 

[KWIKR 1]

Bob , getting new thrust bearings is the easy part . trying to figure out what caused the failure and the remedie is the hard part .

 

[BobbyBuick]

You Are preaching to the chour there.Im on my third one in 2 years.I just checked it after about 20 passes though and it is @ 6 thousands

 

[azgn]

yeah, if anybody has a fix, ideas, anything(!), please chime in...it seems once a certain power level is reached, thrust bearings become a maintenance item.........I have 2 yrs and prolly 150 passes on mine, but my crank moves a bunch...so out it comes

 

[KWIKR 1]

I'm going to try a thrust bearing with a contoured thrust flange on the next one (Federal Mogul #7144M main bearing set) . And even thinking of drilling a small hole into the bearing thrust face threw to the oil passage that feeds the bearing .

 

[BobbyBuick]

And even thinking of drilling a small hole into the bearing thrust face threw to the oil passage that feeds the bearing .

Ive done that with a 1/16 hole into the ceter and counter sink it.
Also filing the surface where the halves go togather helps the releive the oil to the back side of the bearing.I also had the tranny pump modified and dropped my line pressure from 210 to 150.also check the clearance on the convertor into the tranny pump when you bolt it up shouldnt be more the .060 if it is use washers (CHECK FOR WIDTH) on all 3 to be the same and space the convertor into the tranny.Ill lat you know

 

[KWIKR 1]

Bob did you drill the 1/16" hole on the one side only ? I'm thinking that it may have to be done on both sides as not to cause the crank wanting to go one way due to the addional oil on one side only .

file the bearings " are you refering to chamfering the "outside" bearing parting edges on both bearing halfs ? or the mod where you file a smalll chamfer on the one side opposite of the tang on the rear upper flange parting edge for addional oiling on the rear flange ?

 

[Black Demon]

Kwikr,

Are the Federal Mogul bearings fully grooved? The one in my engine now is only grooved 180 deg. The idea to feed the side of the bearing may prove to have some merit. I dont think the guy that designs bearings has gotten in on this discussion. It would be interesting to hear his thoughts.

Mike

 

[KWIKR 1]

Mike I dropped Sean (FM guy) a email about the idea of the oil hole mod on the bearing flange . I've been picking Seans brain pretty hard with a few emails . he maybe a little worn down on the thrust bearing subject . good guy always willing to answer ANY question with sound info.The FM #7144 as far as I know are refered to as a 3/4 groove bearing .I'll report back with any info .

 

[darkfa8]

articles to read...

The first link is what is considered industry standard. The second link
was a site I found and to be honest some of the info is questionable but
interesting to say the least. Let me know if this helps

http://www.atra-gears.com/crankshaft/

http://www.gnttype.org/techarea/transmission/trantsb.html

Joe@ProTorque.com
Joe Rivera
PROTORQUE <http://www.protorque.com/>
1440 Church St.
Bohemia, NY
11716
631.218.8700

This was an email to Eric Schertz (Dynotech Performance) from the owner of Protorque (makers of torque converters). Eric then forwarded it to me to read. Very informative and should give you all some ideas on what to look for as potential causes of thrust bearing failures.