Hello Evo fam,

This is officially my first post and reaching out to you all for advise. Long story short I bought an Evo 9 earlier this year with low compression in cylinder #1. I now have time to dive into it and disassemble the engine and to my surprise I also found what I think is an issue with crankwalk. The crank end play was for sure out of spec. My problem is that the crankwalk was bad enough to not only “mushroom” one side of the thrust bearing surface on the crank, but also made a groove on the block and girdle. I think the crank is junk, but my question is if the damaged part of the block is repairable. Or would I need to source another block?

I suspect that the block is also junk, but wanted to see if there are different opinions. Specially, from people who had similar situation and what course fo action you took.

Please see pictures for your reference and thank you in advance for any advise.


Arrow pointing to “mushroomed” surface. Other side is perfectly flat.


Groove made by the crank to the gridle.


For comparison this is the other side of the same journal on the girdle.


This is the groove the crank made on the block which is very close to the ridge in which the thrust bearing sits.


For comparison this is the other side which looks perfect.


You can see that the damage made like a “chamfer” on one side where as the other side is perfectly square (green arrow).

 

Strange this would happen on a evo 9, crankwalk is a very uncommon problem on later 4g63's. Maintenance must have been slacked at some point. How many miles on the engine? I would also assume the block is no good but maybe someone has another alternative.

 

Well the current engine is not the original engine as the previous owner blew it. However, the engine it had when I bought it only had "2,000 miles" on it. This looked consistent with the conditions of piston/rods (looked new). The coating on the wiseco pistons is basically intact.

 

Probably built to spec incorrectly..I cant think of any other legitimate reason for crankwalk on such a new build. The damage to the actual block looks minimal but I don't want to say its salvageable. Will be watching this thread I am very interested in someone elses input who has experience with this issue.

 

Yes, my thoughts exactly. If the face in which the thrust bearing is somehow warped or mushroomed out I would think that the block is junk. Machining this spot looks to be complicated, but then again I am no expert in machining parts.

 

I would doubt it was crankwalk. The early 7 bolts in the 95 7 bolts in the dsms did that but to me that looks like improper seating of the bearing or it wasn't sitting in there all the way and they just threw it together and ran it.

 

Any thoughts on the block being repairable?

 

I would honestly talk to a machine shop or someone who does motor work to see if that is repairable. Looking at it again what kind of bearings were in the block? Were they tri metal or were they something different? I think that it can be maybe repaired and worked back to normal but I am not someone who can repair that. It just seems odd to me that the bearing would make those kinda grooves in the crank journal if they were the right bearing and or a material not tri metal.

 

It looks to be King bearings when I run the part numbers. They are supposed to be tri-metal.

 

I wouldnt run that block.

You're welcome to ask your machinist, but the reduced ledge for the thrust sit on is no bueno.

 

Yep. I hear ya. I was able to break a piece with my finger nail; its that thin. I guess time to look for another block. Anyone selling one? preferably local to me? :P

 

This changes things then. If that is the case yeah that thing is toast.

I know some places will weld and reshape stuff like that and it is good to go why I even suggested it but if he can pick at it and it falls apart yeah totally different story.

 

Yeah that's why I said ask his machinist. But if it's falling apart that easy, I'd trash it or make a table out of it at this point.. New block is cheaper than another rebuild that will also need a new block.

 

Yep I am agreeing with you again. I think it would make a sweet *** table.

 

I've heard of a similar issue before.
If a machinist can clean up the thrust face on the crankshaft, then it may be reuseable.
The other issue is the thrust bearing clearance. You can't buy oversized thrust bearings.
So you may need to "build up" a thrust washer using a spray-welding method or something similar.
But that will only work if the bearing can be held in the block OK without it falling out.
That ledge you've highlighted may be an issue.