torque converter cover missing bolt

[burnwhatremain]

hey ya'll.

i recently figured out what the terrible vibration/rattle is that i get from my '94 rodeo (3.2L V6): i'm missing a bolt on my torque converter cover on the front end of my transmission (obviously, it's an automatic...)

does anyone happen to know what type of bolt i need? grade, head size/shape, threads, etc.
any and all suggestions would be great.

...along the same lines and merely out of curiosity, anyone know why it really only vibrates between 2k and 2.5k rpms? (my assumption is simply that that is approximately where the transmision is at it's peak before shifting)
and how bad have i been killing my transmission by taking a month to figure out what the problem is? do i have to worry about having lost a lot (or any) fluid from inside?

thanks a lot for any help you can offer.

[Ramblin Fever]

Is your undercarriage coated with ATF? Any drips on the ground?

There is always the possibility of ATF getting out of any hole - I just replaced a $6 seal - shift shaft seal specifically, that's been slowly weeping enough fluid over the course of the last few months to cost me to lose about a 1/2qt a week. If I'd have left alone without consistently checking and refilling the level, I surely would've cost a lot of damage.

These 4L30-E GM transmissions do not like to be low on fluid, so I would recheck the level ASAP - I doubt the missing bolt alone would cause a vibration, but it's possible if you're low on ATF. That little pan holds about a quart of ATF; but you'll have to double check your level.

Not sure if you have a dipstick or not on that particular year - if not, your refill hole is on the big transmission pan in the back corner, the highest bolt on the passanger side. Search through the archives on the correct way to check/fill this fill-plug, don't attempt it without reading up on it, or you may be swimming in a red bath.

Not exactly sure if your vibration has anything to do with the tranny or not; are you having any other symptoms?

[burnwhatremain]

the area hasn't seemed wet, but that certainly does not mean i haven't lost fluid. i'll be sure to check later tonite.

as for the vibration, i know that it's the torque converter cover as i literally crawled underneath while i had a friend rev the engine to the point where the vibration is happening, initially thinking it might just be a broken weld on a heat shield somewhere. i poked around until i saw/heard/felt the problem. when i put a finger and some pressure on the cover, the vibration stopped; at which point i realized i was missing a bolt.

i'm hoping that the cause is past tranny work that wasn't tighted to the appropriate ft lbs, not some greater issue (like stripped threads or something).

i'm going to try to figure out what i need to replace what's missing, and i'll certainly post again once i get it fixed...or at least once i try to get it fixed.

thanks for your suggestions.

[Canucklehead]

As far as figuring out what bolt you need, just remove another one of the cover bolts, check to make sure it will thread into the spot where the bolt was missing and provided they are the same go to your local parts monkeys or Home Depot for a replacement.

[burnwhatremain]

brilliant.

...shame i didn't think of that myself.

thanks.