thrust bearing failure

[Red Regal T]

Broke my thrust bearing cap at 60,000 miles and had to use a different motor. I freshened an 80,000 mile stock turbo shortblock I purchased and installed it in my car. I had no machine work done. I used Clevite bearings. 4000 miles in, while doing some power braking while tuning, I noticed my oil pressure was off by 10-15 lbs at cruise speed. Thought maybe I broke another main cap. Pulled my pan to find the bottom shell of the thrust bearing was down to bare steel. The babbit and copper was almost totally gone. Crank appeared OK. I read information about the torque convertor or trans possibly being the cause. I checked my cooling line pressures and the were normal....30 at idle and maybe up to 45 under load. I also visually inspected my D5 convertor and found no sign of ballooning. I also disconnected it from the flexplate and it slid back and forth freely. Trans doesn't seem to be the problem, but who knows.

Upon installing new main bearings I drilled out the oiling holes in the main bearing shells to 1/4" and chamfered them. I had never done this before. Seems like a good modification for any bearing replacement. My oil pressure is very good and wouldn't think making oiling holes larger would have any adverse effect. I also did the modification of filing the edge of the upper thrust bearing as described in the ATRA bulletin. I'm hoping this will help. Damage seems to occur under hard load.

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

I'd like any other suggestions to help me find the answer to my problem. I'll just be babying it around until I get more info. TIA

 

[Intercooler]

John,

So is this what you are saying:


You broke the thrust main cap and just put another one in its place without a line bore or hone? Or having it checked? .... and now there is a problem? If so I think there could be your problem. Something could have gotten tweaked ever so slightly or isn't lining up right. I have seen first hand the terrible alignment of caps from one block trying to fit its caps on another one. I had a nice standard bore 109 which had gotten the center two main caps hot (blackened them so they are trash!) but didn't spin the bearings. I had a junk 140 NA block sitting there that I took the caps off of to use on the 109..... they wouldn't line up to save their ass!

 

[Steve Wood]

I believe he said he freshened a block he bought.

He did not say if he indexed the thrust cap when he installed the new bearings or measured the thrust clearance.

 

[Razor]

Nah, He swapped motors cuase his first one broke the cap.

Dunno..it typically smells like tranny when these issues come up.

BTW, what was the clearnace between the TQ and the flywheel when you pulled it away. Maybe contact Bruce at PTS and ask what the spacing should be when you pull it away. IOs it 1/4 or 1/2 or ??? If the TQ ballooned a bit, then this number will be reduced.

My .02

Julio

 

[86underboost]

red,
thrust wear can be caused by a number of things. most of the high milers i've seen have some thrust play regardless of of how they were driven, or what shape the converter's in. the only proper way to check a converter for ballooning is to measure it's case front to back plate. once a converter balloons it'll stay pushed out. i can't really remember what a stocker measures, but i'm sure someone can chime in and get you the info you need. sometimes you can't see it with your eyes, sometimes you can't see any discoloration or anything, but measuring it is a precise way to tell. for insurance and maybe a little performance, i'd recomend a good performance converter with an anti-balloon plate. those d5's are notorious for getting fat.

well i hope this new (to you) engine doesn't have any problems and all is well.

hth

 

[Red Regal T]

I replaced the shortblock from the one with the broken cap. When I installed the new mains yesterday, after I installed the thrust beaing, I tried to move the crank forward before tightening the bearing cap. It didn't seem to move. I know it's supposed to be .004 to .007, so I figured that movement is not that noticeable visually. I also noticed on the damaged thrust bearing that the copper sides of the bearings were somewhat "polished" by contact. Noticed I had old ones laying around that did not seem "polished". Don't know if that means anything. Remember, this was a running shortblock that I just simply replaced the bearings.

My plan is to drive it 500 to 1000 miles and then pull down the pan for a look. I also have another trans and convertor to install to see if that eliminates the problem. If that doesn't help, my only other thought is to try a different crankshaft.

More help is invited. Thanks for helping.

 

[Steve Wood]

If the crank will not move back and forth, why run the engine?

 

[Red Regal T]

Why would just replacing the main bearings cause the crank to not move? It may have moved but I couldn't see it. Could you elaborate?

I had to move the crank one way or the other to insert the thrust bearing. After I put it in, the movement was not descernable.

 

[Steve Wood]

Then you need to find out what happened to the crank endplay.

Maybe you should verify that the right thrust bearing was installed. Drop Cal a line and ask him about thrust bearings.

 

[Chuck Leeper]

Checkin the clearance

The cap is to be installed and the bolts/studs pulled up snug, but NOT tight. You then bar the crank forward, tap the cap on it's sides to seat the brg against the crank. You then torque the fasteners down, and check the clearance.. BTW, this is done w/ a dial indicator, not the "eyeball". [.004 to .007 is ok]
Given the last brg failure was on one half of the brg.. it's a good bet you were running w/ 50% brg capacity.. Caused by not installing the crank/brg cap correctly.
Also, the end play on the converter should be 1/8 to 3/16". Any over that, and the pump drive tangs are too far out of the slot in the converter nose. If it's excessive, then shim it back. Pay close attention to the clearances at each drive lug.. I've seen ALOT of converters that have varying amts at the lugs. Bolting a verter down w/ unequal clearances will bend the flex plate, cause starter problems, and side load the ft pump bushing....

My story, and I'm stickin w/ it!!!

 

[Red Regal T]

Thanks for your help. Bearing material gone was across the entire bottom thrust bearing. I must admit, I'm no expert but in all the motors I ever put together, I didn't take care to install the thrust bearing in this proper manner, however, I never had a thrust bearing problem. Either this isn't the cause, or I've just been lucky all my life. Maybe my luck ran out.

I do have dial indicator but why would my endplay be different just because I replaced bearings. This motor was never freshened and no machine work was done. Bearings I used were clevite MS960-P which ARE the correct bearings.

 

[KWIKR 1]

I've been to hell and back because of a thrust bearing problem . what I did on the last assembly before I drop the crank in is the following . I stood the crank upright on a table with a light coating of oil on the thrust journal/face . I then take the half shell of a brand new thrust bearing out of the box . I place it into the thrust journal and make sure it's seated up nice against one side of the thrust face on the crank . Then I take a set of feeler guages and see what measurement I get between the other side of the "thrust bearing face" and "crank thrust face" (eg: .004"-.007") . this measurement should be what you should get (+/ - .0005) when the crank is installed and thrust is "set" . this method worked for me and I got the exact same measurement with the crank installed and thrust "set" using a dial indicator on the end of the crank snout .

 

[Red Regal T]

Thanks for your input. I pretty much used the method as described by Chuck, when I replaced the main bearings yesterday, but I didn't measure the endplay after I installed the bearing. Not having any machine work done, I didn't think I would have any issues.

The engine is in the car. If I have to pull it, you can be assured I'll make sure these measurements are addressed. Because I never had this problem before, I was unaware of it. This isn't much discussed here on the board and if it was, probably would've went over my head.

 

[Intercooler]

I have the correct converter dimensions to see if yours is ballooned and also have the GM stab depth for converter to flywheel if you want them.

I use a dial indicator mounted on the fron of the motor to check end-play. So far I have NEVER had one out of spec.

 

[Red Regal T]

Hey Jesse, I think that would be good information to put on this thread, for me and those who are unfortunate enough to have this problem in the future. TIA

 

[Intercooler]

The converter dimensions is the easy one:

http://www.tciauto.com/tech_info/converter_dims.htm


Bear with me for a little bit...I have scanner problems I am trying to fix so I can put the sheet DelTrans gave me when I picked up my 200 going over GM stab-depth.

 

[Intercooler]

I got the scanner working and now I can't find the paper I had it posted here before and it got deleted. I found almost the same specs here for stab-depth:


http://www.protorque.com/techi/ti_it.htm



So basically .065"- .180". Most spacer washers are .030". I think when I set mine I used .150" measured with stacked feeler gauges. If I find the sheet I will put up those numbers but it was real close to this one.