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Old 12-31-2019, 07:11 PM   #1
WhiteZombie
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Join Date: Nov 2012
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PSM 05 WRX WGN 5MT
95 Caprice 6spd Track Rat

Default *SOLVED-PLUGS* Who wants to play GUESS THAT ENGINE NOISE?

*CHECK THE LAST POST IN THE THREAD FOR SOLUTION - NOT ROD KNOCK!*


Super intermittent!

I first noticed it maybe 5 days ago, but will go full days of driving with no noise, and typically appear/go away only once a drive cycle, if at all. Only really noticeable between 1500-3000rpm and when the car is fully warmed up. Usually goes away before I can stop, pop the hood and listen, but the one time I did, it sounded like passenger side front of motor.

Did a full timing belt kit last winter, and has been driving fine. No driveability issues I've noticed but also trying not to beat on it when the noise presents itself. Any guesses? 106k mile 2005 Subaru WRX Wagon, Cobb Stage 2.

Anything I can look at on my AP to try and figure it out?

https://youtube.com/watch?feature=yo...&v=9e7Kv980AY4

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Last edited by WhiteZombie; 01-10-2020 at 12:26 PM.
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Old 01-01-2020, 10:47 PM   #2
subaru_gc8
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im guessing the ac idler pulley
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Old 01-02-2020, 12:23 AM   #3
WhiteZombie
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Quote:
Originally Posted by subaru_gc8 View Post
im guessing the ac idler pulley

I'm hoping you're right. I'm gonna grab my stethoscope and give it a listen tomorrow, then maybe pull the belts and pulley to feel the bearing after work. I've replaced a few of them, but I don't recall them making quite that type of noise. Good starting point though!
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Old 01-02-2020, 09:54 AM   #4
WhiteZombie
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Seems like the noise changed for the worse, and is now consistent and pretty terrible sounding. Made sure the plugs were snug, didn't feel any tapping and roughness against the timing cover or valve cover. Sounds like something physically hitting together in the valve train, or maybe some super wacky exhaust leak? Going to have to drive the other car to work and investigate further tonight.



Last edited by WhiteZombie; 01-02-2020 at 11:36 AM.
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Old 01-02-2020, 10:13 AM   #5
supermarkus
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pull the timing belt covers and get eyes on the belt. I had a misaligned timing belt guide on the passenger side that made this kinda noise until the car was fully warmed up but it was close enough to the belt to eventually shred it up.
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Old 01-02-2020, 12:09 PM   #6
subaru_gc8
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Quote:
Originally Posted by WhiteZombie View Post
I'm hoping you're right. I'm gonna grab my stethoscope and give it a listen tomorrow, then maybe pull the belts and pulley to feel the bearing after work. I've replaced a few of them, but I don't recall them making quite that type of noise. Good starting point though!
all you have to do is use a long screw driver
'
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Old 01-02-2020, 12:21 PM   #7
WhiteZombie
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Quote:
Originally Posted by supermarkus View Post
pull the timing belt covers and get eyes on the belt. I had a misaligned timing belt guide on the passenger side that made this kinda noise until the car was fully warmed up but it was close enough to the belt to eventually shred it up.

Thanks!
Will do, as well as a few other checks tonight to see what else could be going on.

I did the timing belt on my old OBS EJ22 and forgot to use the belt gap tool and had belt rub but no noise. I eventually noticed when I had the timing cover off like 6 months later. I've done a few Subaru timing belts since then, including this noisy car last February, and ABSOLUTELY use the belt gap tool. I suppose I could see those lil belt guide bolts loosen, however unlikely.

I have a pretty experienced Subaru engine builder buddy that's coming over soon to give it a listen as well.
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Old 01-06-2020, 11:11 AM   #8
WhiteZombie
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95 Caprice 6spd Track Rat

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Long story short - it was a faulty "blown out" spark plug!

1 month old NGK Iridium plug on cylinder 3 developed play/looseness between the porcelain part with the electrode and the metal threaded portion, allowing the combustion air to forces its way out through the small gap, causing a loud knocking with a little 'exhaust poof' noise as well. Plug on Cylinder 1 was also heading down the same path with just a touch of play/clicking when wiggled.

Photos of the two compromised plugs on left vs. at least 2 year old NGK R plug that was in the car when I bought it 2 years ago.


I'm hoping the heat discoloration was just due to the very hot combustion air forcing its way through the plug repeatedly?

Any guesses as to why this would happen to 1 month old plugs? Hoping I don't have some other issue causing them to blow out.....

Video of when we pulled plugs to do a compression/leak down test and found our culprit:
Close up of plug play:

Video of today's drive - no noise, all is well!

Before finding the plug issue I did the following:
Went through and pulled timing cover to check that all was still in time, all the pulleys felt and sounded fine, as well as the tensioner. Crank pulley was tight, no keyway or crank damage. All belt guides tight, gapped correctly.
All buckets spun freely and valve lash measured within spec, no visible debris or damage to any cam lobes or buckets, cam caps tight and cams tight in caps, so we kinda ruled out valvetrain damage.

Tonight I'm going to change the oil, check for any metallic debris and sent the oil out to get analyzed, just to be safe.

Thanks for playing!

Last edited by WhiteZombie; 01-06-2020 at 01:25 PM.
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Old 01-07-2020, 11:34 AM   #9
WhiteZombie
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PSM 05 WRX WGN 5MT
95 Caprice 6spd Track Rat

Default Counterfeit Plugs!!!

I DID call NGK after some buddies reached out to me about VERY convincing counterfeit NGK iridium plugs that they've seen and read about. Sounds like they were mostly sold through Amazon, which is exactly where these came from. The seller no longer sells them but is still active, so I reached out to them and Amazon as well, and in the meantime ordered some freshies from Summit, as NGK guaranteed me Summit will have the real deal. He said Jegs and most other major online car parts places, as well as any reputable brick and mortar parts store should have the genuine articles.

In short, NGK admitted that even they sometimes have a hard time telling the knockoffs apart from the real deal, and the only way they could truly verify is if I sent them in, which I probably will. They're so similar that even the manufacturer can't tell them apart through photos!

BEWARE COUNTERFEIT PLUGS THAT ARE EVEN JUST A FEW BUCKS CHEAPER ANYWHERE ONLINE
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Old 01-16-2020, 09:21 PM   #10
pazzoduc
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Wow. What the hell has the world come to? Glad you figured it out before plug disintegration caused major damage.
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Old 01-20-2020, 11:35 AM   #11
WhiteZombie
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PSM 05 WRX WGN 5MT
95 Caprice 6spd Track Rat

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Quote:
Originally Posted by pazzoduc View Post
Wow. What the hell has the world come to? Glad you figured it out before plug disintegration caused major damage.
You and me both! There's always " I wish I would have checked that first" thought after spending hours checking all kinds of other stuff, haha.

There is a chance they may not be counterfeit, and I just under-tightened them in the head, leading to very poor heat transfer from the plug to head, causing them to overheat, as I did not use a torque wrench the first time around. Definitely made sure they were torqued to spec on the 2nd time around!
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