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Old 03-26-2005, 12:06 AM   #1
skier
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Default Metallic rattle from the engine?

I was hoping you guys would be able to help the noobish noob (me, that is). I've got some weird problem (is it really a problem or I am just a paranoid?...). Sounds like kind of metalic rattle coming from the engine. Not dependant on gas (87-89-91, all the same so it's not knock I guess), depends on revs though, only noticeable through the 1.5k - 2.5k range. Never heard it when tach is higher then 2.5k. Does not depend on engine temp, never really heard it right after the cold start (so it's not a timing belt?)...Apparently, also depends on something else which I have no clue about since sometimes it can hear it and sometimes I can't. Does not depend on oil at all (mineral-synthetic). Loud enough to hear it with the windows up. Clicks rate is very fast, can't tell one from another so can't tell if it changes with rpm change. Nothing else is noticeable wrong, the car itself does not shake or anything like that...

Searched but did not find anything with the same set of symptoms. Any ideas what the heck it might be? Worries me a bit...
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Old 03-26-2005, 12:17 AM   #2
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detonation?
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Old 03-26-2005, 12:37 AM   #3
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Quote:
Originally Posted by garie
detonation?
I guess it should have been taken care of with the higher octane? It haven't though...
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Old 03-26-2005, 12:44 AM   #4
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you sure the sound comes from the engine bay and not some where under your car? As you said, the sound goes away when you rev above 2.5k rpm, does that apply to both during driving and idel? Could it be when over 2.5k rpm the engine sound just covers the rattling sound?

Try have some one rev for your while car is in idle, and try locate the sound yourself. Does the sound comes on all the time or only during bumpy surface?
If you recently worked in the engine bay, try check around that you didn't forget or drop anything in there.
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Old 03-26-2005, 12:45 AM   #5
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heat shield?
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Old 03-26-2005, 04:30 PM   #6
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i hear the same noise to on my 02rs and 97 legacy gt...im guessing its the heat sheild, or im hoping it is
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Old 03-26-2005, 04:42 PM   #7
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crappy throw-out bearing? I know mine does this from time to time and I can only hear it under 2.5K rpms. Is the pitch more of a high squeal rattling or a lower more bassy rattle?
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Old 03-26-2005, 06:05 PM   #8
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my legacy is an automatic and i still hear it....my rs is 5spd and i still hear it on that car too
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Old 03-26-2005, 07:36 PM   #9
The Undead Subaru
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my car clicks/rattles too, and i'm pretty sure i've got some bad lifters, don't know how bad the problem is though or if i should bother replacing anything
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Old 03-26-2005, 09:16 PM   #10
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Quote:
Originally Posted by silvscorp
you sure the sound comes from the engine bay and not some where under your car? As you said, the sound goes away when you rev above 2.5k rpm, does that apply to both during driving and idel? Could it be when over 2.5k rpm the engine sound just covers the rattling sound?

Try have some one rev for your while car is in idle, and try locate the sound yourself. Does the sound comes on all the time or only during bumpy surface?
If you recently worked in the engine bay, try check around that you didn't forget or drop anything in there.
just tried to reproduce the problem when idling. Nothing. No rattles, no cli(a)cks through the problematic rpm range (1.5k - 2.5k). So I guess it only appears when in gear (does it mean that the engine itself is fine?). It's relatively loud, so I am sure I'd hear it if it appeared after 2.5k. All is fine there. Not bump-related, might easily appear on nice and smooth pavement.

Quote:
Originally Posted by atmosphere
crappy throw-out bearing? I know mine does this from time to time and I can only hear it under 2.5K rpms. Is the pitch more of a high squeal rattling or a lower more bassy rattle?
Hard to describe really. I'd say it's more high-pitch then bassy...kinda like little metallic chirr...

Thanks for the replies guys, hopefully I'll be able to find it with your help...
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Old 03-27-2005, 12:38 AM   #11
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yea i hate those little problems like this, you experience it everyday and yet can't figure out what's wrong. So if you don't hear any sound during idle and if you think it's gear/trans related, here are couple more qs for ya: what gear do you usually hear the sound? 1st? 2nd? if so try replated in higher gears, see if it happens at every gear during low rpm..

well this is off topic, my friend's talon tsi is also having wired problem at around 2k rpm. while keeping foot steady the rev automatically bounce up and down at 2k rpm. Everything is normal if revs above that.. anyone got a quick idea about that? sorry, don't mean to hijack the thread... -_-
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Old 03-27-2005, 03:12 AM   #12
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my heat sheild seems to be rattling (crappy winter did it in :P) and it only rattles off throttle (rev, shift, rattles till it gas it again)
What can be done? Cant you just cut it off?
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Old 03-27-2005, 11:00 AM   #13
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find out which part and why is rattling. do you have aftermarket dp? If the heatshield itself is not physically damnaged then just tighten up all the bolts should do the job.
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Old 03-27-2005, 11:12 AM   #14
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If you had an older vehicle I would think about loose baffles in the muffler or some similar issue. Check for dented or loose exhaust pieces underneath and bump the exhaust with your fist to try to duplicate the noise while not running.
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Old 03-27-2005, 12:37 PM   #15
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I've got very similar symptoms on my 05, goes away around 3k. I pretty much only hear it in 2nd and 3rd though. It went away for a few weeks and now its back. When I go over a bridge with the windows down, you can really hear it. I'll check the exhaust tonight.
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Old 03-31-2005, 12:42 AM   #16
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I just don't get it. It completely dissapeared yesterday I didn't even touch the heatshield...nothing has changed. Oh well, let's wait till it starts rattling again...
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Old 05-03-2005, 05:20 PM   #17
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Just got back from the dealer. He diagnosed my rattle as engine knock. I looked in the manual and noticed that it says not to be concerned about occasional pinging, especially going uphill, but this is pretty frequent. I've been using shell 87 or 89 all the time from the same station. Oil consumption also seems high at ~2 quarts in 3300 miles. I'm going to try switching to BP 89 from now on.


I don't remember this occuring before I switched to synthetic at 4500 miles, should I switch back to dino when I change the oil this weekend?

Blake
05 RS wagon
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Old 05-03-2005, 06:46 PM   #18
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timing belt tensioner
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Old 05-03-2005, 07:02 PM   #19
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I'm pretty sure someone would have mentioned this already, but I can almost guarentee that it's the Y-pipe heat shield. I bottomed out in Boston one time and for about a year I couldn't figure out why I heard a metal-on-metal rattling. Then one day I was under my car and noticed the heat shield got OWNED. Fortunately the exhaust pipe and all surrounding parts made it out alright.
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Old 05-04-2005, 12:17 AM   #20
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I would stay with synthetic oil for many reasons. If its not physically leaking it, oil consumtion shouldnt be an issue with a new motor. It absorbs crud, moisture and heat better than mineral base with less internal friction thus giving better mileage and performance. Preignition is produced by incorrect fuel mixture and or too much timing. When the oil gets too much color drop it and replace regardless of the miles on it and you can beat it all you want.
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Old 05-04-2005, 03:31 AM   #21
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your '05 car should not be detonating. Did the dealer offer any possible problems that could cause this?
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Old 05-04-2005, 10:10 AM   #22
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The dealer said bad gas, which in my limited experience means they don't want to really investigate the problem. It has done it on at least 6 tanks of gas, either 87 or 89. I put in some octane booster, so I'll see if that helps. Here is the thread that made me think about switching oil:

t=704520&highlight=knock
(sorry for the format, I can't post urls yet apparently)

It's hard for me to imagine that rings don't seal after 4500 miles, but this problem started shortly after I changed to mobil 1 10w30. I've checked the exhaust a few times and can't get anything to move at all, much less rattle. Is there an easy procedure to check the tensioner? Thanks.

Blake
05 RS wagon
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Old 05-04-2005, 11:04 AM   #23
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What weight oil are you using? 2 quarts in 3300 miles is rediculous. The detonation tells me that you are getting excessive oil in your combustion chamber. Let the engine warm up and pull your plugs. If they are oily then you have issues. Pull your air box and check for oil where the pcv hose comes in. A little is ok/normal.


I suppose it could be a gas issue, but with that much consumption I doubt it. Go back to a good dyno oil and see if it helps.

Update please.
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Old 05-04-2005, 11:11 AM   #24
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Same prob here.....05 RS. Started around 2,500 miles. I have 89 octane in now to see if it stops. It definetly sounds like detonation. I havent changed the oil from factory, so its not that. I am going to mobile 1 synt 5w30 soon to see if that helps, but I doubt it will.

Edit: I checked the oil and it was down to "add", but the engine had just been shut off. I added a little (half quart). Will check today when cold.
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Old 05-04-2005, 11:35 AM   #25
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Sometimes cast rings do take time to bed in but usually no more than 3000 miles you would think. Read your plugs if its eating that much through the combustion chamber it will be noticable. Hopefully its not plugging up the cat in the process. Ive also heard that synthetics wont let the rings seat due to not enough friction. I have people run at least the first 2 oil changes with mineral base before switching over. MD if you feel that you switched too early it wont hurt a thing to go back, too bad the dealer isnt being more helpful.
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