I 've got a 99 runner as well as a 2001 siverado pickup V6 automatic.

I've been lurking on a Chevy tech forum and many there claim a pressure trans flush can and has caused problems by circulating debris throughout the transmission.

There were more than a few people and techs who tell stories of perfectly good cars going to the dealer/lube joint for a trans flush and leaving...........never to drive the same way or needing expensive repairs.
Anyone here ever experience similar things with their Toyota??
Kenny S

 

I think it depends on how long it's been since you've last done a transmission flush. If you're at regular service intervals, you should be fine...

if you're at 200K and still using the same fluid you drove off the lot with, you should probably keep driving it until you need a new transmission.

 

Working at a dealership, I encounter this all the time. If you have gone an insane number of miles on the original tranny fluid(like 140k to 200k), then flushing would only make the problem arise sooner. When you drive an automatic transmission, the clutch plates inside naturally degrade over time. If you postpone the flush way too long, the car may drive ok before the flush but since the fluid contains all of the clutch debris, new fluid would only let the clutches slip against each other. Old fluid= gummed up fluid which can help with the friction of worn out clutch plates. New fluid= fresh fluid which if your clutch plates have degraded early from gummed up fluid, will make the slick clutch plates slide against each other resulting in transmission slippage and/or no engagement of any gear at all.

Basically change your fluid at the respcted service intervals, and this will help your fluid stay clear and smooth. Otherwise just keep running with the old and let the tranny go out all on its own.

 

I had my fluid flushed out at 99K and since I bought the truck used with 67K on it, I have no idea if the truck every had a tranny flush. I now have 136K and only have seen improvements in the way the truck shifts.

 

The way I understand it is that they don’t use an external pressure pump, they use the transmission pump on the vehicle so it has the same pressure when swapping the fluid as it does when you are driving. As long as the transmission is not already damaged you should be good.