Big Dave

I'll bring my compression test kit to the bar on Thursday. Tonight will be just a hunt for the source of the noise.

jetrainor

Got my fingers crossed.....my problems started with a knocking, which later turned out to be crank on bloock journal because of thrust bearing failure which as we know results from flex plate issues.

camboinc

well, Big Dave came over for a listen. he doesnt believe we are having a TB issue. engine runs smoothly enough so probably not a jumped TB. i climbed under the car after he left and pulled the oil filter and drained the oil. the belly pan plug had no unsual amounts of metal bits and no copper for sure. the oil filter had literally just a few tiny flakes of copper- not enough to equal a grain. got a second opinion from another friend who is a super wrench. he thought the metal in the filter was not at all unusual. so i refilled with mobil 15w 50 synthetic and put on a new oil filter. with the scope, the tapping sound is most pronounced from the bottom of the motor- the belly pan on the passenger side in that front quadrant of the pan if you will, just an inch or two from the edges. i also heard some odd tumbling sound from the driver side and lower center of the bell housing. almost sounds like bolts rattling around in there but not quite. maybe just a loose metal sound.

i cant quite get under the car the way it sits now on the jack stands. i may try again later tonight. again, my suspicion is still a lower motor issue like rod or main bearing. can work be done on the bottom of the motor while in the car or does it have to come out?
i will check the flex plate before doing anything else, just wanted to post an update. thanks again big dave for stopping by.

Big Dave

No problem, Brian.

The sound is a dull thumping, a lot like the noise your fingers make when you drum them on a table. At first I suspected a misfire or exhause leak at the manifolds. Almost a popping noise. The car seems to be running normally...idle is good.

The stethoscope reveals a faint ticking under the thump, so I can't rule out metal-metal contact. It's certainly not lifters, injectors or the chain tensioners. The sound is louder under the car.

Does anyone have access to a sound clip of bearing knock noise? I'll try to stop by again on Friday with a video camera and post something for all the Rennlist doctors.

WICruiser

Sounds like the flex plate / thrust bearing is a good place to go next. That will help clear up if there might be an internal thrust bearing related issue and you might also find out that the problem is related to the flext plate given the rattling sound you are describing. Could it be that the high rpm excursion that started this noise resulted in a flex plate mounting failure?

Big Dave

We talked about that. Brian is going to pull the bottom bellhousing cover next.

Bill Ball

The rattling from the bellhousing could be a loose flexplate to flywheel bolt(s) or flexplate the TT clamp flange bolt(s) or the TT clamp itself or even a fractured flexplate arm. Who knows, it may the source of the knock-like noise, transmitted down the crank. So, check the torque on all the bolts and don't forget the flywheel cheesehead bolts, for that matter.

Flywheel 66 ft lbs
TT clamp 58-66 ft lbs
Flexplate to flywheel 23-28 ft lbs
TT clamp flange to flexplate 39-46 ft lbs