Weird drivetrain clunk

Flywheel, Clutch, Transmission, Axles, etc...

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DeusExMachina
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Weird drivetrain clunk

Post by DeusExMachina »

I have a problem with my 1991 Legacy Turbo Sedan. It mostly happens in 1st gear (5MT) and sometimes 2nd gear. When going straight and I go to WOT, the car makes a loud *CLUNK* noise, and the gear whine I have changes sound pitch. It becomes less loud and deeper. The same thing happens in 2nd gear sometimes, if I start in 2nd, or if I baby it so as not to clunk in 1st gear, and go to WOT it will do the same thing. Its less loud when it does it in 2nd gear, making a soft clunk like a rock hitting the undercarriage and changing the pitch of gear whine.

I don't want to jump to conclusions, but I think it could be clutch related, or the timing belt has possibly jumped/lost a tooth. Any ideas? Thanks.
mTk
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Post by mTk »

Does it happen when you shift only when accelerating fast? Sounds like it could be worn out mounts. engine tranny, diff etc.. Or just rear diff clunk, unless it just started doing it.

MK
Last edited by mTk on Mon Jun 14, 2004 9:11 pm, edited 1 time in total.
1992 BC672 AWD 5MT
BAC5.2
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Post by BAC5.2 »

Where is the noise coming from? Could be the rear end clunking, could be engine/tranny mount related. I doubt it's clutch related though.
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IronMonkeyL255
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Post by IronMonkeyL255 »

hehehe.....

One of my friends had an XT6 that was diong about the same thing from the rear of the car.

It turned out to be the rear diff. mounts.
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That being said, everything I post is accurate to the best of my knowledge.

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Brat4by4
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Post by Brat4by4 »

change your tranny mount to the STi group-N piece. then see if it still makes the same noise. also check to make sure an engine mount hasn't ripped in half.
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DeusExMachina
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Post by DeusExMachina »

It only makes the noise when accelerating in gear, not shifting.

It comes from pretty sure the front of the car, below the driver or forward of that.

Still sound like tranny mount? Tranny mount was inspected and they said "its fine" so I don't know. The engine doesn't make any odd movements that I can see from revving with the hood up. I'll have to crawl under and look at the mounts one day though.
DeusExMachina
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Post by DeusExMachina »

I may have isolated the problem. Looking through the service manual tonight, I check out the engine troubleshooting guide. They give all kinds of sounds, and next to "loud, dull metallic knocking sound" they have "If oil pressure is normal" which I believe it is, since the oil light isn't on, two problems: "Engine mounting failure" or "Loose flywheel attachment bolts". Hmm. Hopefully the new clutch/flywheel I'm getting done soon will fix my problems!
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