What is it, or why is it bad to get your transmission serviced with a Power Flush???I have been told that it is very bad for a transmission, but, Why? T.I.A.

I was talked into it on my car & wish I had not. In my opinion it stirs up any dirt & such but is done through the dipstick so the shop doesn't have to do any real work like changing the filter or removing & replacing the transmission pan & gasket & resealing properly. Your pan could be full of chips & you'd never know it. They can't adjust the bands.IMHO, this allows oil change type places to charge for another service... without really getting their hands dirty. If you are going to bother, I'd suggest going to a qualified transmission shop & at least get proper service.

Over time, if the trans fluid isn't serviced regularly, then the fluid tends to 'varnish'. New fluid is generally high in detergents, and break down the varnish.. then there's chunks now floating through the passages.. This can cause major issues. Not always, but enough to consider.

Here is a good write up on changing your trans fluid. Simply dropping the pan only nets around 4 quarts, doing it like described in the write up will get you closer to double. On top of that, I allowed it to drip over night and netted another 2 quarts or so for a total of approximately 10 quarts. It's a bit time consuming, but IMO getting as much drained as you possibly can is important. http://www.genosgarage.com/faq.asp Scroll down until you see the link for changing the trans fluid. It is in pdf and I couldn't link it directly.

Here is a good write up on changing your trans fluid. Simply dropping the pan only nets around 4 quarts, doing it like described in the write up will get you closer to double. On top of that, I allowed it to drip over night and netted another 2 quarts or so for a total of approximately 10 quarts. It's a bit time consuming, but IMO getting as much drained as you possibly can is important. http://www.genosgarage.com/faq.asp Scroll down until you see the link for changing the trans fluid. It is in pdf and I couldn't link it directly.

Thank you, for the link and the information, I will be servicing my transmission this afternoon!!!

I recently opened up a high mile 47RE that I got for a core to rebuild. No varnish, no junk. Personally, I think that doing a proper flush (using the trans cooler lines) & then changing out the filter/adjusting the bands will be just fine. I did it in my 96 Tahoe (Everyone told me not to) & it did another 68,000 miles without incident.IF you do the flush & not the filter/bands, you are just wasting time.Ed

Personally i have seen trannies go out after getting their first flush with high miles. If you do them since new then they are less likely to go out. I have been doing trans filter, adjust bands, and replacing govenor pressure sensor and solenoids

Personally i have seen trannies go out after getting their first flush with high miles. If you do them since new then they are less likely to go out. I have been doing trans filter, adjust bands, and replacing govenor pressure sensor and solenoids

The reason for that is small particles of dirt/bands/metal get put into a place that the fluid goes but due to the flow it 'falls out' of the flow and collects. When a power flush is used the flow is not the same and it dislodges the built up crap in the lines. That crap goes a little farther down stream and plugs things like the check ball in the cooler lines ans starves the transmission for oil even though it was full.

OK, time to debunk some myths...When properly flushing a transmission, there is a clear 6" round tube. It is about 4' long. It is filled from the top with new trans fluid. The top end is connected to the trans cooler input. Bottom end is connected to the transmission line. At the bottom, there is a sliding piston.You start the truck & the pressure from the transmission pump pushes old trans fluid into the cylinder. That in turn moves the piston. In turn, the piston pushes the new ATF into your trans through the cooler input.THAT'S IT !!!!!Now, you have cycled all of your transmission fluid with new through the cooler lines.Now, you remove the pan, replace filter & adjust bands properly.My Tahoe was underwater for about 40 minutes in the swamps of Floriduhh. Strawberry milkshake came out.I abused the snot out of it for 4 more years without ever touching the trans again. I went through 3 engines, but the trans was fine.Ed

I think that is key to the trans flushing is getting the pan off and changing the filter and adjusting the bands.

I drop pan and filter, adjust bands every time and then take the front cooler line off the tranny and use compressed air and blow out the cooler line circuit and then put small amounts of air back into the converter and it pushes out about 2 more quarts, I have always gotten about 2.5 gallons out using that method which is pretty much a complete flush. While the pan is off It gets a heavy shower with brake cleaner to wash off all the residue from inside the case around the valve body as well. I have never lost a tranny yet in my 5 Dodge rams and putting roughly 1/2 million miles and counting between them over the last 18 years and all fairly hard use.