87' Transmission Rattle

[rsammel]

I have a mean rattle from the transmission (I think) in my 87' 2.5L 4WD. Sounds like a couple of screws in a blender. The sound is present at all times, but if I let the truck idle, then rev up the motor, the sound dissapears just before it returns to idle...then comes back. Replaced the entire clutch assembly a couple years ago, including the throwout bearing, and did the internal slave earlier this summer (for the third time). Truck shifts and drives great, except there is a heavy hum/vibration in the dash when decelerating - not sure if that is related. Tranny fluid was almost a quart low when I checked/ refilled today. I have basically ruled out exhaust rattle. Help me Obi Wan Kenobi...

 

[HOrnbrod]

Check both the motor and transmission mounts. They are probably the originals and the rubber's rotten and you're getting resonant vibes.

[glundblad]

Check both the motor and transmission mounts. They are probably the originals and the rubber's rotten and you're getting resonant vibes.

My '87 does the same thing.  The transmission mounts need replaced.

[cruiser54]

Yup.

 

[Comavalanche]

Just had the same issue. Turns out it was my exhaust hitting against the crossmember. Loosened it at the flange, moved it away and then tightened it up and it was good to go.

[rsammel]

Thanks guys, I checked the transmission mount, and while it looks like the rubber is separating a bit, the noise doesn't seem to be coming from there. I combed over the entire exhaust while the truck was running and again found nothing. Next I'll check the motor mounts - where exactly are they located?