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Old 07-20-2005, 03:39 PM   #1
Scooby Newbie
Member#: 91702
Join Date: Jul 2005
Default 2000 Impreza 2.5RS Rod bearing failure HELP!

Hi very first post on this website so hopefully some you suby savvy people can help me out. It came to us first with a bad engine noise wich sounded like a rod bearing. The owners explained that he was bombing down the highway with the peddle to the mat and all of a sudden started hearing a knocking noise. Low and behold, #2 & #3 rod bearings were badly scored as was the crank. Everything was spec'ed out; crank bearings were spec'ed and ground, new rod bearings from subaru aslo spec'ed before install, erverything was cleaned and double checked and new gaskets. I should also mention that he has cat-back exaust, performance chip, iridium plugs/wires. About two weeks later 1500 kms, he comes back with again bad engine noise wich of course sounds like a rod bearing and again #2 & #3 crank bearing are done. Now before he recieved his car, oil pressure was checked a found to be ok. There are no signs of detonation on the pistons, no heat discoloration on the crank journals or rods. What gives!!! Ive been reading alot lately and have seen this issue resolved with a short block, but to go and buy a short block without knowing for sure the reason for this mess is kinda stupid. Any help is apreciated.
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Old 07-21-2005, 12:47 AM   #2
Scooby Guru
Member#: 5218
Join Date: Mar 2001
Chapter/Region: MWSOC
Location: SAUL'S Motorsports
96L Most Over-
Developed Beater


There is some mention deep in the archives of different (size) oil passages on the outer 2 rods which may (and have) cause(d) bearing failure on the inner rods at sustained high RPM. It was also attributed with sustained high lateral g loading such as seen in roadracing. More details from your customer may shed more light on the subject.

PM "zzyzx" and ask about what type of bearing failure he ended up with a couple years back. TWE ended up doing the rebuild iirc.....

Jay Storm
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Old 09-13-2005, 10:20 AM   #3
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Member#: 88106
Join Date: May 2005
Location: Buffalo, NY
2010 2010 legacy GT
Black mica


hey, i dont know if im having the same prob but since you guys have then maybe you can diagnose mine, i posted it on here but i ll repeat it again.....
In the morning when its cool out my engine makes a knocking sound that seems to be coming from the center of the engine somewhere...the sound virtually dissappears when the engine is up to OT.. I also dont get the sound at a constant rpm unless the engine is under a load.. I can produce the sound just by blipping the throttle in the morning or when the engine is cool but at a normal idle there is really no sound... Its definately a knocking sound..... Does this sound like the symtoms of a bad rod bearing to you guys?

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Old 09-27-2005, 05:05 PM   #4
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Member#: 1140
Join Date: Mar 2000
Chapter/Region: SCIC
Location: San Diego
2000 S201 #78, '95 L
'13 F150 Ecoboost


Sounds like oil starvation. You may have some debris in an oil passage. Replace the block.
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Old 09-28-2005, 02:04 PM   #5
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Member#: 96154
Join Date: Sep 2005
Chapter/Region: MWSOC
Location: Beecher, IL
98 2.5RS


For both of the above situations, I would replace the block. You never know if you are going to have problems in other parts of the block later down the road that are related to this issue. Replace the block and never have to worry about it again. You'll save the hassle of having to do it AGAIN if you replace. (at least in my opinion)
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Old 09-28-2005, 04:16 PM   #6
Scooby Specialist
Member#: 11808
Join Date: Oct 2001
Location: Cape Coral,FL

You might also want to check the crankshaft for jounal taper. Another thing to check is rod straightness I.E. wrist pin to jounal but, you really need a surface table, dial indicators and Jo-blocks for this. A new/different block may not solve this problem and I suggest you find the problem before going ahead blind. JMHO. ed
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