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Old 04-15-2013, 06:33 PM   #1
RallyB
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Default Bad timing belt tensioner???

i have a 2007 impreza 2.5i. Recently i just noticed a "slapping" sound on cold starts going along with the cams. When i start the car cold the rpms jump up to 2,000rpm, after a few seconds it drops back down to 1500rpm and thats when the "slapping" sound comes in. It literally sounds like a belt is slapping up against something but i am confusing it for piston slap at the same time. Also once i start driving the car and it warms up the sound goes away. The sound really isnt all that loud and im pretty positive it isnt piston slap but think it may be the timing belt tensioner.

I just had a mechanic check it out (in a lazy manner) and he said there are no internal problems with my ej25 and that if the tensioner were bad the car would run like s**t.

Any help would be appreciated! The same mechanic is going to check all timing and accessory pullies for me tomorrow.
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Old 04-15-2013, 06:58 PM   #2
MikeC5
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I bought a car with a bad tensioner recently and it made a very obvious slapping noise that sounded like something hitting the plastic belt cover. It would only occur at idle speed or slightly above, when above that rpm it seemed to run fine and it didn't appear to have jumped any teeth on gears. So I wouldn't assume it would necessarily run bad.
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Old 04-15-2013, 09:19 PM   #3
cal_look_zero
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Quote:
Originally Posted by MikeC5 View Post
I bought a car with a bad tensioner recently and it made a very obvious slapping noise that sounded like something hitting the plastic belt cover. It would only occur at idle speed or slightly above, when above that rpm it seemed to run fine and it didn't appear to have jumped any teeth on gears. So I wouldn't assume it would necessarily run bad.
Well that's disconcerting. I just did a premium t belt kit on my 05 2.5i and it makes the sound that something is slapping the belt cover. I pulled the timing covers off and checked my belt tension and tightness of the bolts thinking that's what it was. Thinking I should replace the tensioner now.
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Old 04-15-2013, 10:51 PM   #4
RallyB
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Yeah I will be getting mine checked out by someone again tomorrow, I just have that gut feeling its the tensioner. Just started her up after letting it sit for an hour and now its knocking and slapping at the same time and sure seems to be coming from that cover. Ive put $350 in repairs into this thing within a week already and now this -__-
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Old 04-16-2013, 01:03 PM   #5
kero
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Did you consider piston slap??
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Old 04-16-2013, 04:20 PM   #6
RallyB
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Yep and I've basically confirmed it isnt piston slap. Im just starting to wonder if it may be new car time. This impreza needs front struts, I still dont know what my slapping sound is for sure, the rear diff sings, and theres an oil leak (for the 3rd time in a row). Im not the type to just give up on a car but my wallet is empty and I dont have anymore patience
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Old 04-16-2013, 04:45 PM   #7
yarrgh
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Have you removed the inspection cover and actually witnessed the tensioner? that's the easiest way to diagnose it. And if you have no money to repair, how do you have money for a different car?
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Old 04-16-2013, 05:41 PM   #8
RallyB
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Im having my mechanic do just that this week, and I have money for a new car because I can sell this one and another vehicle that I have or trade them both in and whala a new car can be mine
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Old 04-16-2013, 07:35 PM   #9
RallyB
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Or I sell the other car and dump more money into the impreza, not sure how to go about it
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Old 04-16-2013, 11:31 PM   #10
BruceD_500
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Sounds very much like the noises my OutBack was making with it's bad (e-bay) tensioner.
It ran just fine. I also found that the bolt holding the tensioner on was over tightened and striped the threaded mounting hole.
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Old 04-17-2013, 08:16 AM   #11
RallyB
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Ouch, just had the mechanic tell me there was some slack on the tensioner, guess it was just enough to alarm me
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Old 04-17-2013, 05:55 PM   #12
yarrgh
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I recently had a similar sound on cold startups. Just for the hell of it, I removed the timing belt to listen to the idler pulleys. The tensioner had a little hydraulic fluid leaking, but according the manual this can be normal. The fix was to compress the tensioner (slowly, of course) a couple of times and then reinstall it. So far, so good.
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Old 04-18-2013, 03:09 PM   #13
RallyB
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Well turns out the tensioner had some slack, and 2 pullies had bad bearings which were causing the pullies to not rotate correctly and create a wear spot on my timing belt a.k.a my good hearing and persistance saved my engine. Same guy that did the timing belt last also changed my head gaskets...........uh oh
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Old 04-29-2013, 01:35 PM   #14
RallyB
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Well now the belt is STILL slapping and I can hear the brand new pullies moving
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Old 04-14-2014, 02:26 PM   #15
SixSpeed5
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Hey guys, new to these Subaru engines, whats the best way to tell if a tensioner is bad? Have a friend with a 2002 Outback (2.5) and it makes a knocking/slapping sound around 1500-2000rpm. Only makes the noise when its GOOD and warmed up, like 30 minutes of driving. Kind of sounds like piston slap, but since it doesn't do it when cold and it takes so long after it warms up for the noise to start I am thinking it might be tensioner problems.

The noise is kind of hard to pinpoint. Her timing belt/tensioner were replaced about 15000 miles ago. Sounds like it isn't too hard to mess up the installation a bit.
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Old 04-14-2014, 04:21 PM   #16
SixSpeed5
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Here is a video of the problem

http://youtu.be/IUmJmRII-GY (Should be available in HD soon, easier to see whats going on)

Timing belt seems to vibrate a lot when the noise is the worst.
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Old 04-16-2014, 12:32 AM   #17
C_Austin
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Quote:
Originally Posted by SixSpeed5 View Post
Here is a video of the problem http://youtu.be/IUmJmRII-GY (Should be available in HD soon, easier to see whats going on) Timing belt seems to vibrate a lot when the noise is the worst.
Yes, it looks the hydraulic tensioner has gone. Make sure you replace the other timing belt pulleys when you have the belt and tensioner done. They can also go bad and can cause serious engine damage if they fail completely.
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