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Old 09-04-2012, 03:27 PM   #7
BrandonDrums
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Member#: 118630
Join Date: Jun 2006
Chapter/Region: South East
Vehicle:
2005 Wrx wagon
Red

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Quote:
Originally Posted by UK-Wagon View Post
OP,
Did you install a new crankshaft with the second engine? or was it resurfaced?
Also what was the cause of the failure on that second engine??

*To add a note here,
Im a subaru certified tech, for warranty purposes we cant replace many of these parts like, oil pan, oil pump, oil cooler or any of the related lines. We are instructed to flush them and inspect the oil pump for damage. The oil pump can be completely stripped down, cleaned and inspected. If its scored or scratched in the pump housing then yes, it is to be replaced. Ive yet to ever have a engine come back with spun rod bearings for not replacing any of those parts. You just have to have the right parts cleaner and time to make sure it is 99% clean.

I have had 2 engine Ive built come back, but it was many miles later and in both cases they were on the track during the failure.

For built engines, oil clearances and other things cant be put to OE Spec tolerances or clearances for that matter or you will have failures. It takes lots of time and knowledge to get these things correct. I often have to have bran spakin new crankshafts sent out for machining! Yes even the Nitirde cranks are not good enough for me. Many get .005 thousandths removed to get my clearance right where i want it. I dont do this for warranty jobs, but I do for customers that want built engines.

Keep this in mind too, I NEVER trust machined crankshafts for over size bearings in a Performance application. They dont last!!!! New Nirtide cranks are only $325..... Turned/machined cranks after a bearing failure are just worthless and youre asking for it to happen again very soon. Ive got a pile of cranks here going to the scrap yard. Many are saveable for turning but I just dont risk it anymore.
Humm, that's an interesting take. The rod-bearing material on newer engines is so hard to mate with the nitride cranks, I'm surprised that what you described is still the dealer SOP for those types of repairs. Especcially when throwing all the additional oil passages of AVCS systems into the mix. I can understand the need to throw out the crank because polishing it means removing most if not all of the nitride coating in which case you'd need to use older, softer bearings with because the harder bearings need the nitride coating to prevent them from wiping out. Soft for Soft, Hard for Hard.

All the things you described should actually be replaced on newer, nitride coated engines. Subaru really needs to hop on that bandwagon because those new bearings designed for use on the nitrite cranks are so much more dangerous than the old lead filled bearings. A shard small enough to get past the pickup screen and through every oil passage in the car is still hard enough to seize a bearing now. Those old ones were more like foil and didn't pose a threat if they were small enough to get past the pickup tube every once in a while from what I understand.

To answer your question about my 2nd engine, I think the rods block and heads were original, the crank and the pistons were brand new. The block was bored due to scoring from the blown ringland by .002'' in each cylinder and .002'' cold-gap was used to fit weisco forged pistons and rings.

ACL bearings matched to OEM clearances for the rods and mains were used and the heads were checked for leaks, resurfaced and re-used.

Here's where it gets fuzzy, the oil cooler was used but I don't know if it came from the 2.5 w/ the ringland failure or from my 2.0 with the bearing failure. Judging by the picture, it's certainly used although I was never told explicitly if it was used or not.

You can tell, the oil cooler in this pic is used. By which engine, who knows.


The only thing I've been told by that shop was that "a couple of years ago we never replaced the oil coolers on rod bearing failed engines, we'd just clean them out like crazy but we kept getting those engines back with new failures over and over so now we just replace it" They did my build "a couple of years ago" in Nov of 2010.

That's not the point though, my engine was put through hell through it's relatively short life. The first tune on it was absolute crap and the street tune that replaced that first tune turned out to knock around 3200 rpm a whole lot when I bought a laptop and started to log and peek at learningview. For 4 months it had been knocking and learning view was a nice little hodgepodge of 5-10 degrees of learned timing retard, namely from .7-1.10 g/s of load at 2600-3400rpm. THAT'S when I decided to learn how to tune myself which lead to other abuses.
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Last edited by BrandonDrums; 09-04-2012 at 03:48 PM.
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