99 XJ Automatic
stock suspension
190k miles
I have a faint popping/knocking sound that can only be heard from inside the cabin. It seems to be coming from under the driver seat floorboard. You can hear it popping erratically (like popcorn) when sitting still, and it is definitely worse in gear then in neutral or park. I can also hear it when rolling with no foot on brake. It can be felt in the steering wheel and brakes. It's driving me crazy.
As soon as I accelerate it goes away. Car drives great otherwise and is very smooth as long as I have my foot on the gas or am going faster than ~10 mph.
I first checked flexplate to TC bolts, and 2 were loose so I removed, cleaned, and then reinstalled just those 2 with loctite (I know, dumb). The sound seemed to go away for a few weeks then it returned very quickly. I went back under and did the same for the other 2. The sound did not get any better (vibes did). There were no cracks that I could see. Transmission shifts no worse than it has for many years.
I've done motor and trans mounts within past year so doubt it is that. I did replace my exhaust header with an APN, and had to loosen exhaust hangers to make it line up with downpipe/donut. However, hangers are very tight again so don't think it is that either.
I bought a mechanics stethoscope to try and track down the source. The only place I can hear the knock, is by putting the stethoscope directly on the unibody. Then it has a very faint and hollow sound, but I can clearly distinguish it.
I've put it all over the exhaust pipe (testing hangers), engine/head (stuck lifter/tick), motor/trans mounts, transmission/bell housing, belt drive stuff, flexplate area, etc and I can't hear shit. All I hear is a smooth running engine.
Put it on the unibody near driver's side and you can hear it clear as day.
Any ideas as to what the fkkk would be causing this? Other places to stick my stethoscope?
Thanks for the help. This is driving me crazy :confused1
stock suspension
190k miles
I have a faint popping/knocking sound that can only be heard from inside the cabin. It seems to be coming from under the driver seat floorboard. You can hear it popping erratically (like popcorn) when sitting still, and it is definitely worse in gear then in neutral or park. I can also hear it when rolling with no foot on brake. It can be felt in the steering wheel and brakes. It's driving me crazy.
As soon as I accelerate it goes away. Car drives great otherwise and is very smooth as long as I have my foot on the gas or am going faster than ~10 mph.
I first checked flexplate to TC bolts, and 2 were loose so I removed, cleaned, and then reinstalled just those 2 with loctite (I know, dumb). The sound seemed to go away for a few weeks then it returned very quickly. I went back under and did the same for the other 2. The sound did not get any better (vibes did). There were no cracks that I could see. Transmission shifts no worse than it has for many years.
I've done motor and trans mounts within past year so doubt it is that. I did replace my exhaust header with an APN, and had to loosen exhaust hangers to make it line up with downpipe/donut. However, hangers are very tight again so don't think it is that either.
I bought a mechanics stethoscope to try and track down the source. The only place I can hear the knock, is by putting the stethoscope directly on the unibody. Then it has a very faint and hollow sound, but I can clearly distinguish it.
I've put it all over the exhaust pipe (testing hangers), engine/head (stuck lifter/tick), motor/trans mounts, transmission/bell housing, belt drive stuff, flexplate area, etc and I can't hear shit. All I hear is a smooth running engine.
Put it on the unibody near driver's side and you can hear it clear as day.
Any ideas as to what the fkkk would be causing this? Other places to stick my stethoscope?
Thanks for the help. This is driving me crazy :confused1