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Old 04-28-2012, 01:34 PM   #1
Ostrowrx
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Default Can A Cam bearing take out a rod bearing.

So I had a 2.5 non avcs wrx motor built with 04 sti heads, and sadly it devoured a rod last week after 3500 miles. So I went to take it apart and when I removed the cam cover on the passenger side I discovered that the rear cam bearings were not tightened down as seen in the pic. Now I'm no enine expert so I'm looking for an opinion on whether or not the cam bearings not being tightened could have created enough metal to take out the rod to crank bearings? Let me know wht you think! I know one bolt looks tightened but its not.

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Old 04-28-2012, 01:51 PM   #2
AREA1320
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Actually you don't have cam bearings.. But it's possible that with the cam caps not being tq'd to spec that material could have made its way to the rods.. But unlikely that that's the root cause. It was most likely something else... And judging by the over use of sealant on the valve cover contact points they most likely over used it somewhere else starving the motor
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Old 04-28-2012, 02:17 PM   #3
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Yeah, way too much silicone on that thing. All it takes is a tiny piece to break off and clog an oil passage.

Between the overuse of rtv and the loose cam cap, I'd be leaning toward something else being over looked, incorrectly installed, or improperly measured causing the issue.
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Old 04-28-2012, 04:37 PM   #4
john 1badSTI
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I would have to say that the rod brg failure was due to overuse of rtv,he has it globbed all over the upper end,can only guess how much was used assembling the bottom end.
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Old 04-28-2012, 06:28 PM   #5
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I even found some stuck to the cam shaft. Only a tiny piece but it ws def there
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Old 04-28-2012, 10:22 PM   #6
kellygnsd
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who assembled that motor?
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Old 04-28-2012, 11:18 PM   #7
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Quote:
Originally Posted by john 1badSTI View Post
I would have to say that the rod brg failure was due to overuse of rtv,he has it globbed all over the upper end,can only guess how much was used assembling the bottom end.
So what you are saying is that a piece of silicone dislodged, got past the screen of the oil pickup, then got past the 40 micron oil filter and then lodged itself into a crank bearing.


OP thanks for the clear photos. Most people take a crappy phone pics and think that is sufficient.
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Old 04-28-2012, 11:25 PM   #8
wrxsubiemod
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The builder obviously missed a few steps. Got crazy with silicon and probably didn't check the bearing clearances.

Engine build fail 101
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Old 04-29-2012, 12:11 AM   #9
jesterjames
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Quote:
Originally Posted by 2milehi View Post
So what you are saying is that a piece of silicone dislodged, got past the screen of the oil pickup, then got past the 40 micron oil filter and then lodged itself into a crank bearing.


OP thanks for the clear photos. Most people take a crappy phone pics and think that is sufficient.
I think he's saying that who ever assembled the motor went to ****in town with silicone. If. He used a ton on the case halves the excess could judd into the oil passages for the bearings
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Old 04-29-2012, 12:13 PM   #10
oldandslowjim
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you COULD have a lub. prob. as oil would flow from the loose caps droping flow and pressure to the other bearings plus the extra oil then has to drain back to the pan lowering the level in the pan
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Old 04-29-2012, 01:00 PM   #11
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which cylinder knocked a bearing ? if the cam was that loose -
a) you would of heard a problem in the head
b) the motor would probably had a misfire as those valves were never going to operate correctly
c) I am surprised it lasted 3500 miles like that

it musta sounded like a bucket of bolts

are you sure it knocked a bearing and its not just the loose cam journal you were hearing ?
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Old 04-29-2012, 05:28 PM   #12
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Not sure if it could cause a rod bearing failure, but that is completely un-friggin-acceptable. Whoever built that engine needs to be fired from life, or at least lay off the booze while building. I can't believe they put sealant around the spark plug hole gaskets. Complete and utter fail.
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Old 04-29-2012, 07:09 PM   #13
john 1badSTI
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Quote:
Originally Posted by 2milehi View Post
So what you are saying is that a piece of silicone dislodged, got past the screen of the oil pickup, then got past the 40 micron oil filter and then lodged itself into a crank bearing.


OP thanks for the clear photos. Most people take a crappy phone pics and think that is sufficient.
NO if too much was used on the case halves it could have squeezed out and got in an oil passage that feeds oil to the mains after the filter.
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Old 04-29-2012, 09:11 PM   #14
timeXlost
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Quote:
Originally Posted by john 1badSTI View Post
NO if too much was used on the case halves it could have squeezed out and got in an oil passage that feeds oil to the mains after the filter.
this.
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Old 04-29-2012, 10:27 PM   #15
2milehi
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A lot of assumptions - let us ask the OP.

So does it appear that there was excessive amount of sealant used around the block halves?

What makes you suspect a rod knock? Is there a bunch of bearing material in the engine oil (oil pan area)?
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