My Thrust Bearing has Failed
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From: Anaheim California
The thrust bearing shoulders are about 2 mm thick as I recall so with the allowable end play of .10-.4 mm 16 valve engine but only .008-.24 for 32 valve .... that is interesting did not know that the specs changed until I just looked. I wish you well with this latest challenge.
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From: Buckeye, AZ
The spec changed with 32 valve?! Ew...
Brent: That machining looks like the factory machining to me and not from TBF. Hard to tell from just one shot. You may have dodged the bullet.
Brent: That machining looks like the factory machining to me and not from TBF. Hard to tell from just one shot. You may have dodged the bullet.
They Smashed My Truck!
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Ok at the risk of sounding like an idiot, I need to know. What is the thrust bearing? Is it a porsche name for main bearing? the pics above look like crank walk to me. Am I right?
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From: Buckeye, AZ
Crank walK? I need to ask what that is! 
No, seriously, read more about TBF here:
OOPS! Theo's page seems to be down. Here's the link anyway.
http://jenniskens.internet-land.nl/T...s/TechTips.htm
No, seriously, read more about TBF here:
OOPS! Theo's page seems to be down. Here's the link anyway.
http://jenniskens.internet-land.nl/T...s/TechTips.htm
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From: Buckeye, AZ
Try this as well:
http://members.rennlist.com/v1uhoh/9...earticleTH.pdf
Edit: I had a hard time getting the pdf from Tony's site, so I am re-hosting it here:
http://www.billsworkshop.com/P928S4/...earticleTH.pdf
http://members.rennlist.com/v1uhoh/9...earticleTH.pdf
Edit: I had a hard time getting the pdf from Tony's site, so I am re-hosting it here:
http://www.billsworkshop.com/P928S4/...earticleTH.pdf
Last edited by Bill Ball; Mar 3, 2006 at 12:22 AM.
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Originally Posted by FeedNfrenZ
Well finally got the oil pan off and confirmed it! TBF! However the good news is the block may be good. I think that I caught it in time.
I agree w/ Bill B., those marks on the block look like machine marks done at the factory and not your crank, but its hard to tell from the photo's.
Take a look at these shots from the Koenig motor (its an 88 block). Its got similar machining marks on the block and cradle, and I discovered a very worn thrust bearing also. My end play was 0.22mm .
My TB bearing measured 2.36mm (front side), & 2.29mm (back side). So there's a little bit of 'meat' on the TB ends. If your end play is .050" (1.27mm), its outside the wear limit, but I think there's enough there to still protect your block. (I hope so at least...) See pics below.
Did your magnetic tip in the oil drain plug pick anything up? I had constant "silt" on the Koenig motor plug at each oil change (much more than the S4 ever had), figured out it was the main/rod bearing when I tore it all apart. Perhaps cut open the oil filter and look for aluminum pieces (if you suspect the block).
Hope indeed your block is ok, just trying to share a similar experience with my rebuild. Good luck.
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From: Buckeye, AZ
Hey, Bill:
That thrust bearing is worn through to the copper, but is mostly there compared to Brent's. Your endplay was within spec, but the bearing was technically worn out. I really need to re-check my endplay. I had been using the incorrect spec of 0.4MM, while Jim pointed out it is 0.24MM for 32 valve cars. Eeek!
When I did my oil pan gasket I saw the block machining and got nervous, but Marc Thomas reassured me that it was factory machining. Here's a picture of real TBF damage from Rich Andrade's review:
The thrust bearing in the picture is new.
That thrust bearing is worn through to the copper, but is mostly there compared to Brent's. Your endplay was within spec, but the bearing was technically worn out. I really need to re-check my endplay. I had been using the incorrect spec of 0.4MM, while Jim pointed out it is 0.24MM for 32 valve cars. Eeek!
When I did my oil pan gasket I saw the block machining and got nervous, but Marc Thomas reassured me that it was factory machining. Here's a picture of real TBF damage from Rich Andrade's review:
The thrust bearing in the picture is new.
Last edited by Bill Ball; Mar 3, 2006 at 03:55 AM.
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Originally Posted by Bill Ball
Hey, Bill:
That thrust bearing is worn through to the copper, but is mostly there compared to Brent's. Your erndplay was within spec, but the bearing was technically worn out. I really need to re-check my endplay. I had been using the incorrect spec of 0.4MM, while Jim pointed out it is 0.24MM for 32 valve cars. Eeek!
When I did my oil pan gasket I saw the block machining and got nervous, but Marc Thomas reassured me that it was factory machining. Here's a picture of real TBF damage from Rich Andrade's review:
That thrust bearing is worn through to the copper, but is mostly there compared to Brent's. Your erndplay was within spec, but the bearing was technically worn out. I really need to re-check my endplay. I had been using the incorrect spec of 0.4MM, while Jim pointed out it is 0.24MM for 32 valve cars. Eeek!
When I did my oil pan gasket I saw the block machining and got nervous, but Marc Thomas reassured me that it was factory machining. Here's a picture of real TBF damage from Rich Andrade's review:
Was kind of surprised to find my TB's worn into the copper on disassembly. Odd thing is, the front side is worn the worst. (it's usually the back side that's worse, from what I've read.) Have no idea why, perhaps from the S/C belt...
I was trying to point out to Brent that even though he's got a worn-out TB (which sucks BTW), I think his block's ok still (but I could be wrong because I'm not there to see it...). From measuring my block / cradle sitting on the floor here, I figure the crank has to wear away about ~2.0mm of thrust bearing material before it starts contacting the block, plus the crank counterweights have a slight offset too on the main TB journal. But that's only my observations with one motor.
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From: Boulder Creek, CA
Originally Posted by jarroyo
Ok at the risk of sounding like an idiot, I need to know. What is the thrust bearing? Is it a porsche name for main bearing? the pics above look like crank walk to me. Am I right?
Brent, I'm really glad to hear you got to it in time. Looks pretty likely you've saved it.
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I have seen similar wear on the 944 motor I had just overhauled. The block looks ok and the bearings definitely took it for the most part. There is another strip of metal under the copper. When that goes, so does your block. You should be able to rebuild it.