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Premature thrust bearing wear, need opinions

MichaelSuch

10+ Year Contributor
932
37
Jun 30, 2008
Pinckneyville, Illinois
So lately my car has been dying/idling low when I push the clutch in, and last night it felt like either the clutch was slipping or like it was a missfire. When I got to town the clutch engagement started varying and when I did a little 3rd gear pull ECMLink picked up a little knock around 4k rpms (my CEL came on when it picks up knock). I just put in a new clutch a week ago (Fidanza 4.3) and my master cylinder was leaking a little so I thought it could've been that but I decided to check endplay anyway. I measured it a .020 and I believe that the service limit is .009. I just recently put all new bearings in this thing less than 3 months ago, it probably has a total of 5,000 miles on it. Yes it has seen some spirited driving, but it is also my DD so I don't get it on it all the time.

This will be the 3rd build this year for me. Thank god 2011 starts tomorrow, hopefully it will be better. I know the previous builds were my fault, but this is something I couldn't control.

What do I need to do to make this thing near bulletproof? Last time when I spun rod bearings I put in a used crank, it measured at around .005" endplay when I put it in 3 months ago. Now I'm considering going with a new forged crank, something with no miles and hopefully something that will last.

I'm also considering doing that and stroking it. I do currently have Wiseco 8.3:1 pistons and Manley rods with about 40,000 miles on them. I also had a head job done as well. I'm not sure what the compression is on the motor since I never really did one, it does pull very hard though. My vaccuum at idle with the FP2 cams was around 19 in hg. But I never had the engine bored out, it was just honed so I wonder if they were every completely seated.

What is all needed to stroke it? Stroker crank, and stroker pistons? I also have FP2 cams in it, will I have enough piston to valve clearance? If I stroke it I do plan to bore it out, have the block decked a little along with the head if the surface is not flat.

Or should I just throw in a new 2.0 crank and be done with it? This is a street driven car, it is my DD when it's running. It will see some track time. My goals are 400hp. Currently it is stock turbo but plan on moving up to a 20g or holset when the time is right and the car is perfect.
 

donniekak

DSM Wiseman
5,623
973
Mar 23, 2008
Surprise, Arizona
You need to get another block. If you measure the thrust surface on your block/girdle, it wont be perpendicular to the crank centerline. This causes an uneven clearance between the crank, and bearing, which leads to contact, and failure. This is why crankwalk blocks always walk again.
 

donniekak

DSM Wiseman
5,623
973
Mar 23, 2008
Surprise, Arizona
Ahhh I see... How does the thrust surface no longer come perpendicular? I pulled the thrust cap and it was not ate into the block or anything. But the crank was ate up a little.

It not being perfectly perpendicular from the factory is why the bearing wears unevenly, and eventually wears enough to cause problems. If you take a walking block apart before it is out of spec real far, the wear pattern is apparent on the bearing. Only part of it will be worn, while a major portion of it is in new condition. This is from a high spot caused by the misalignment of the thrust surface. There is no oversized thrust bearing for a 4g63, so re-machining the block thrust surface isn't an option.
 
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