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Old 10-14-2012, 12:42 PM
oldhickory oldhickory is offline
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T-400 intermittent squeak rattle in park and drive

hello everybody. i posted a question before on hotrodders, and got some awesome help. so thankful for this site.

i've got a new problem, this time with my transmission. (i think)

I have an '85 chevy 3/4 ton 4x4. engine is a 402. tranny is a th400 that works great aside from being a little slow to go into reverse, and a slight leak from the the pump o-ring. (i think)

Here's the problem: When i start my truck, after the temp sensor on the block hits 150 +-, i hear what can only be described as a squeak/rattle. (sounds like a spun bearing almost, but it is very 'chirpy'.) It is intermittent, and usually goes away a couple of minutes after the thermostat opens up. the sound occurs in park, while the engine is at a fast idle, and also occurs in drive while at any speed, but goes away when i increase rpm's. The sound is definitely coming from the front of the transmission as determined by the screwdriver to ear test.

i call it a squeak/rattle, because it seems squeak more when going over rough patches in the road. again, the transmission seems to work fine, but the sound is getting louder, and i am beginning to notice a vibration while accelerating uphill. (no vibration apparent upon release of gas pedal.)

also, the torque converter has a bit of a wobble to it, which it has had ever since i bought the truck two and a half years ago.

One more thing to add: the other day it rained, and i drove in the rain, thoroughly wetting my undercarriage. The sound went away, and did not occur again for a couple of days. This caused me to think it is something external, but perhaps the humidity did something? I live in the dry desert of southern new mexico.

Sorry for all the words, but i have been searching hi and lo on many forums, and am about to pull the tranny, but just thought i'd put my problem out there.

I have tightened the flexplate to converter bolts, which were a little loose. i did not see any cracks. i have a suspicion that my TC bolts may be loose, thus causing the wobble?
Any suggestions would be greatly appreciated.
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