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Guest Message by DevFuse
 

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Interference or not?


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38 replies to this topic

#26 Guest_Legacy777_*

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Posted 13 January 2003 - 12:16 PM

did you replace the belt tensioner when you did the t-belt?

honestly, I can't see how just the coolant alone would cause it to jump timing unless the belt was not properly tensioned.

#27 Guest_kickerz_*

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Posted 13 January 2003 - 12:59 PM

I did not replace the tensioner but did follow the exact instructions on how to compress the tensioner and the tension on the belt seemed to be good when I put the engine back together....

#28 Guest_TinyClark_*

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Posted 14 January 2003 - 03:38 AM

If it did indeed jump and cuase catosprophic failures, you can tell by doing a compression check. Are you sure it jumped at all? Are the timing marks actually off? Do the compression test before you jump to conclusions.

#29 Guest_kickerz_*

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Posted 14 January 2003 - 07:44 AM

Did the compression test last night and found at least 150 psi in each cylinder which is good! That was a huge load off my back. Still concerned to why it jumped time in the first place though. I did notice last night that the timing belt cover which is placed over the crank shaft pulley was not there. Its the cover that Subaru put on as a result of cars jumping time while being shipped from over seas. I know my particular car was built in IN. so not to sure if it would have even had one. Most of the area dealers said that it is highly unlikely that coolant made the belt jump, they suggested to check out the condition of the tensioner. When I took it off last night when re-timing the engine, I noticed some extremely thick black fluid on top of the seal where the plunger comes up. Possibly a leaky tensioner????? When I compressed the tensioner it felt normal and when I released it after putting the timing belt on it seem to tension the belt properly. Still not 100% confident of the engine not doing the same thing again.:(

#30 Guest_WAWalker_*

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Posted 14 January 2003 - 10:37 AM

If it is a '98-'99 it's prob. a bad tensioner. There were problems with some of those.

#31 Guest_Legacy777_*

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Posted 14 January 2003 - 12:26 PM

I'd replace the tensioner. That's most likely what caused it to jump.

Especially if you're seeing black goo from it.....

#32 Guest_ccrinc_*

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Posted 15 January 2003 - 07:36 PM

OK, updated info from some research...
the EJ20T is definitely interferential, both Japanese and American models. This info comes from a colleague who specializes in high performance Subaru stuff, and whose word I trust.
As for the EJ25 SOHC, do you guys want me to go to the trouble of posting photos of a couple of trashed heads we have? Trashed because the timing belt broke and the valves hit the pistons. The pistons are busted up and the valves are broken off completely. This particular engine is a 2001 model.
(Slipped timing at only 2 teeth may not cause a problem. Usually, the belt needs to be 3 or more teeth off for parts to connect. OR, revving over redline!)
Man, you were lucky!!
Interference can come from pistons and valves connecting OR valves hitting each other. Both are possible. The issue is that not enough room is left for either to clear each other. It's part of the price you pay for the added performance and efficiency.

Emily
www.ccrengines.com

#33 Guest_WAWalker_*

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Posted 15 January 2003 - 07:53 PM

<img src=http://www.ezboard.com/intl/aenglish/images/emoticons/ohwell.gif ALT=":\"> Wonder how many R's that '02 engine was turning to crash that hard? I'll bet they were "Just driving along";) Have heard that one before.

I read in a 2001 Impreza owners manual that the computer will cut fuel to prevent engine over rev. Didn't say at what RPM though. Said "in the red zone". Float the valves in an interferance engine and things could go to he!! in a hurry, cumputer may not be fast enough.

#34 Guest_Legacy777_*

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Posted 16 January 2003 - 09:21 AM

There should be engine rev protection in the ECU.....it should take away ignition......but yeah....like you said...may have not been quick enough......or if you have a chip or aftermarket ecu, they may have bypassed it.

#35 Guest_kickerz_*

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Posted 17 January 2003 - 01:51 PM

Update on my 2.5 that jumped time.... I took the timing belt off and turned each cam by hand back and forth at the pully to see if anything was tight. Low and behold the drivers side upper cam was stiff as hell! Tore into the head and found metal dust in the head cover once it was taken off the engine. The cam bearing cap closest to the driver or towards the rear of the engine was cooked! I took the cap bolts off and found the cam bearing surface destroyed!! Needless to say, a new head with new cams and valves will be on it by this coming Monday. I'll upload some pictures of the damage on Monday.
Still not 100% confident of why this happened in the first place. I have it at an area shop that works on Subys all the time and he was confident that he'll find the root cause of the problem when he removes the old head.

#36 Guest_WAWalker_*

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Posted 17 January 2003 - 06:31 PM

:( Sorry to hear that. Emily at ccrinc may know what happened if it is a common failure.

#37 Guest_ccrinc_*

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Posted 17 January 2003 - 08:45 PM

Actually, cams seizing in the head is way too common. It's an oiling problem: not enough oil getting to the cams.
There are a variety of reasons, starting with the fact that the oil passages in the heads are ridiculously small.
Probably the most likely reason is the plate on the back of the oil pump that backs off, lowering not necessarily oil pressure, but circulation, just enough to cause problems.
Subaru never did anything to keep the small screws holding it on from loosening up. The oil gets out the sides of the pump and circulates like crazy in that area of the block, but any distance away from the pump and the circulation can be dismal.
Eventually, premature bearing wear can result from this also.
Best advice, when you replace front seals and pump o-rings, put those screws back with a little bit of Locktite!

Emily
www.ccrengines.com

#38 Guest_Frag_*

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Posted 18 January 2003 - 03:28 PM

Emily,
you write "pump o ringS" .
I'm preparing to replace the belt on my 96 Brighton and was under the impression that there was one (1) oil pump o ring to replace.
Is there more than one.
The dealer where I buy my parts only sold me one.

#39 Guest_WAWalker_*

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Posted 18 January 2003 - 06:32 PM

Yes there is only one o-ring. Even if the screws are tight on the back of the pump I still take them all out and Loctite them.




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