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Old 04-14-2002, 06:42 PM   #1
RS2000
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Question burning oil and loud knocking sound coming from cyl. 3 ?

Anyone know what might cause this. I don't think its piston slap or a rod because the noise gets quieter as the engine warms up. If it was either of the 2 wouldn't I hear it more as the oil warmed and thinned out. Could it be a crack in the cyl. wall. I would like to hear as many opinions as possible. Thanks.
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Old 04-14-2002, 06:48 PM   #2
AaronB
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When I blew my motor, I had noise coming from the number 3 that got quieter as it warmed up. Not to scare you, but I would get a compression and leakdown test asap.

How did it happen? Did you just start it up one morning and hear it, driving hard, cruising, etc.?
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Old 04-14-2002, 07:37 PM   #3
RS2000
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I just noticed it one morning, then over the next week it got louder but it would always quiet down a bit after warming up. I got the valves adjusted and it has quieted it down some but it is still there. What was it exactly when you blew your motor? What was causing the noise?
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Old 04-14-2002, 08:36 PM   #4
Fitz
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A compression test wouldn't hurt. That would at least eliminate the blown motor theory... although like Aaron, both of my blown 2.5's had similiar symptoms. The other thing yuou may want to think about scondary to the compression test, is a timing belt tensioner. I know mine rattles when cold right now.

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Old 04-14-2002, 10:14 PM   #5
HndaTch627
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sounds like a spun bearing to me....be cautious before you lose a rod.

jeremy
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Old 04-15-2002, 02:09 PM   #6
bryanw
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Same problem here. Mine started bout 6 months ago and has gotten really bad in the past 2 months. Before the weather warmed up (it's 80 right now), even when it was a mild 30 degrees, it would take 15 miles on the highway before the tapping went away. This morning, with the temp around 60, it took only 2-3 miles before it went away. But it is definitely worrying me.

Which one is #3? Is there a diagram somewhere? Mine seems to be coming from the front-left (driver's POV) of the engine, around the A/C.

One strange thing I've noticed is that the longer the car sits without being driven, the longer it takes for the tapping to go away. The other day, the car sat for a day and a half. The next time I drove it (40 degrees), it took over 30 miles for the tapping to go away.

Oh, and no forced air on mine. Just N/A.
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Old 04-15-2002, 02:50 PM   #7
AaronB
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From standing in front of the car looking in the engine compartment:

3 4
1 2

So 1 is the passengerside closest to the front of the car.

It is also labeled on the coil pack right on top of the engine

Regards,

Aaron
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Old 04-15-2002, 02:57 PM   #8
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Would not be a spun bearing if load and revs makes the noise go away.
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Old 04-15-2002, 03:12 PM   #9
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I am getting the exact same sort of noise with my 2.5 as of last night. this is immediately following a hard day of autocross in the rain.

I have a compression tester, can anyone tell me what the numbers should be?

thanks.

jeff
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Old 04-15-2002, 03:50 PM   #10
waren
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Default comp test

I have a manual that gives the range for psi from a compression check but its at home. It is dependent on a lot of things so its hard to say what it should be [engine crank speed, cam timing, elevation etc]

make sure that the TB is wide open. And the batt has a good charge.

Most street engines will give around 150 psi. BUT the key is that no cylinder is less than 80% of the highest value. So If you get one cyl. with150 psi ... your cut off is 120 psi. If one cyl. is down on compression start looking for problems.

If the noise goes away it could be an oiling problem. Maybe your turbo is starving the block?

Also as an engine warms the psitons expand becoming tighter in the bores ... this is why my EJ25 sounds like a diesel when I start it and it quiets down after.

I always worry when I hear a new noise

Hope everything is OK.
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Old 04-15-2002, 03:51 PM   #11
RawCode
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Whenever I let the car sit all night or long ehough to get cold it makes a tapping sound. But it ONLY does it when I go above 2000-3000 rpm, and also only when cold. SO now I let it warm up for a bit in the morning, and then drive easy until I hear not tapping of anykind. It is just like the oil or the heards are not warm yet...

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Old 04-15-2002, 04:05 PM   #12
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Mine's just the opposite. It does sound like a diesel like somebody else said. The sound is strongest at around 1800-2000 RPM. And it goes away at about 2700 RPM.

I was thinking it was an oiling problem as well. But I don't know enough about oil circulation to draw any real conclusions.

Speaking of oil circulation, did you hear that Toyota has recalled a bunch of cars (including Lexus) because of oil gunking? It was only on two of the engines, the 2.4 and 3.0 I think. They claimed it was caused by owners not following the recommended maintenance schedule, but they've redesigned the system.
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Old 04-15-2002, 08:35 PM   #13
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the turbo isn't starving anything...at idle, the turbo barely moves, if at all, and in any event, he has a nice braided feed and return line, so not an issue
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Old 04-16-2002, 12:29 AM   #14
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Quote:
the turbo isn't starving anything...at idle, the turbo barely moves, if at all, and in any event, he has a nice braided feed and return line, so not an issue
Where does the WRX get it's oil supply for the turbo?
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Old 04-16-2002, 02:28 AM   #15
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my compression was at 185 (I think) all around . It is always good to see the same numbers.
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Old 04-16-2002, 03:07 AM   #16
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Quote:
Originally posted by waren


Where does the WRX get it's oil supply for the turbo?
backside of #3 on the cylinder head.

compresion should be between 165-185psi

jeremy
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