Intermittent Knocking Noise
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Intermittent Knocking Noise
After the GM dealer stuck in a new tensioner pulley in my '93 SSE */C, I started getting kind of a hollow sounding knock at times when shifting into gear, accerlerating from a stop & when hitting bumps. The noise is coming from the back of the engine, underneath & to the mid right.
I took it back & they diagnosed it as a broken left front lower motor mount that was causing the RF motor mount to jump excessively. Replaced the broken mount & still had the knocking as before.
Took it back again, they checked for anything loose, & came up with with a bad RF endlink. I'd actually already had the LF endlink replaced with a K5255 (Moog) at Firestone after it had broke when banking on a right turn after the pulley work at the GM dealer, so I took it back to Firestone & had them replace the RF endlink with the same.
But I still have the knocking sound as before, except it now doesn't seem quite as loud & frequent - it'* mostly now when shifting into forward 1st thing in the morning & when hitting a series of bumps.
I'm sure it was something the GM guy did when he changed out the pulley. Afraid he somehow broke that mount & that damaged something else, &/or did something to the stabilizer bar. Is that possible for that job? Any ideas?
I took it back & they diagnosed it as a broken left front lower motor mount that was causing the RF motor mount to jump excessively. Replaced the broken mount & still had the knocking as before.
Took it back again, they checked for anything loose, & came up with with a bad RF endlink. I'd actually already had the LF endlink replaced with a K5255 (Moog) at Firestone after it had broke when banking on a right turn after the pulley work at the GM dealer, so I took it back to Firestone & had them replace the RF endlink with the same.
But I still have the knocking sound as before, except it now doesn't seem quite as loud & frequent - it'* mostly now when shifting into forward 1st thing in the morning & when hitting a series of bumps.
I'm sure it was something the GM guy did when he changed out the pulley. Afraid he somehow broke that mount & that damaged something else, &/or did something to the stabilizer bar. Is that possible for that job? Any ideas?
Last edited by boa12; 04-07-2009 at 09:16 PM.
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Sorry Dan, was just trying not to go into too much unnecessary detail. I've had a lot more done by that dealer including putting on a new (rebuilt) charger. Of course they couldn't just change the coupler.
This all started with the rattle noise, which they 1st tried to correct by putting on new belts, & when they got the part in a new tensioner pulley. It was after the pulley install, that I got the knock noise.
The charger sounds fine now. The tensioner pulley moves some w/ the engine running, which I think is normal.
It'* hard for me to locate the knock from the driver'* seat. But it seems to come from the back of the engine, underneath & more to the right.
This all started with the rattle noise, which they 1st tried to correct by putting on new belts, & when they got the part in a new tensioner pulley. It was after the pulley install, that I got the knock noise.
The charger sounds fine now. The tensioner pulley moves some w/ the engine running, which I think is normal.
It'* hard for me to locate the knock from the driver'* seat. But it seems to come from the back of the engine, underneath & more to the right.
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They replaced the water pump too in the 1st go 'round. I don't even know enough to take the belt off. This seems more like it'* from engine movement, since it happens when hitting bumps & putting in gear.
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Check all the pulleys. If you have a friend to help you. Have him put it in gear while you watch the engine. Watch for play and slop. Watch all the engine mounts.
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Thanks, Dan!
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In the meantime, anybody have any ideas on how a mechanic breaks an engine mount & what else he might have screwed up by just changing a tensioner pulley? It took him like 3 hours to do it, & then he releases it with a broken mount. Not to mention the LF endlink broke off right after.