Hello.I have a 96 Grand Marquis LS with 160,000kms on it. The car has a bit of a vibration when it shifts into o/d.I am told it is likely what is referred to as a torque converter lockup shudder and I need to change the transmission fluid.I have read conflicting accounts with respect to a flush. Some say don't do it as it could move debris around the system and cause problems while others say that's the only way to go. Totally confused. Thanks
Hold the gas pedal steady when cruising at highway speed, then tap the brake pedal. The torque converter should unlock, then relock in a few seconds, and you should feel the shudder again. If you don't, it's not a torque converter problem.
The wrong fluid can cause that shudder when the clutch locks up. You don't need to flush the system. Normally a fluid and filter change is sufficient. As for that debris, there had better not be debris circulating with the fluid. That will chew up seals real fast and it means the filter isn't doing its job.
I drag a tandem axle enclosed trailer with my '88 Grand Caravan that's bigger than the van, and after 237,000 miles, it has had one filter and fluid change in its lifetime only because I had to replace a rusted $3.50 side cover. Of course that is the last of the really tough non-computer-controlled transmissions. I'm not sold on transmission flushes as a fix for an existing problem, but a fluid change can't hurt. It's good maintenance if nothing else. Don't do as I did with my van.