This question is for my GEMS P38, but same engine and similar transmission. There’s a very noticeable vibration while idling at a stop in gear. It still seems apparent in Park or Neutral as well, but not nearly as noticeable. When driving at speed with the torque converter in lock-up it seems to be very smooth. When kicked down a gear without the converter locked up the vibration is very apparent, but as soon as it locks up it’s smooth. I am suspicious of the torque converter, but I really have no experience with this to have a good idea. Any suggestions or advice from you all is welcome.

 

Maybe check motor and transmission mounts? I had a harmonic dampener go bad once, but vibrations got worse at high speed.

 

Thank John. I put a floor jack under the engine and lifted it a bit. As far as I can tell the engine mounts seem fine. Maybe I should remove one at a time to check them better?

 

A complete failure would have been obvious. If actually removing, better to replace with new. New D1 mounts are not expensive.

Make sure the exhaust is not rattling too.

 

Thanks. I hope it’s just mounts but I really don’t think so at this point.

 

I recently developed a knock on my 94 that I was sure was mechanical. Turns out the exhaust gasket on #2 had blown out.

How are your plugs and wires? Maybe time for a compression check? The HV coil terminals on my GEMs 96 have gotten very corroded in the past. Check those with a mirror. White powder is bad, shiny brass or aluminum is good.

 

Thanks again. Plugs and wires are new. It seems to run smoothly when cruising with the torque converter in lock up.

 

And I guess I should do a compression check. I replaced the HG’s less than 2 years ago and everything looked good inside.

 

Honestly I'd check the flex plate. When they crack or are just barely hanging on you will get all sorts of vibrations.

I had a good customer with a D2 which I worked on for a good bit. It always had a little vibration to it but besides that she was a great D2 (Non SAI which was really rare for 03). Well I hadn't heard from the owner in a good bit and then he called me saying his transmission was INOP. I had done a filter/trans fluid change as maintenance about a year earlier and the fluid was in good shape with no burnt smell or anything. Knowing the HP24 is a strong unit I went over to check it out, and it would barely more or nothing at all. I had it towed to my house, found him a replacement transmission, tore into it and when I was removing the transmission I heard this awful sound and metal flew out from the bell housing. His flex plate was completely in 1,000,000 pieces and just the converter sitting against it was holding it together until I pulled the transmission back. A 40.00 part was the cause to all his issues. I told him about it, and he was like well you've got it all apart so just swap the transmission out anyways. I slapped it all back together with a new flex plate, and that vibration it had since day 1 of me working on it was gone. Which means all that time it was already cracked and causing the vibration. It had this one little notch on the old flex plate and basically when it would slip it would sometimes catch the lip of the bent piece and engage and cause it to drive. Then when you shut the D2 off and started it up again it wouldn't catch aka = no drive. Crazy how that part is so cheap but so critical!

 

Thanks Best. I do have a spare transmission/ transfer case assembly that’s supposedly good. On my next day’s off I plan to take a look at a couple of the items John mentions. A simpler fix would be nice but I don’t think it will be. I replaced the plugs and wires for the vibration but it’s still there. Also not throwing any codes.