I'm gonna get the fluid changed in my auto 1989. One place said they back flush with Dex 3 for $60. Another shop said their machine replaces the fluid as the old is pumped out. So I'm guessing that isn't back flushed but is $80. And a good local shop told me a flush there would be $100 with Dex 3, but said their Dex 3 as more conditioners or something. And they flush the usual way, but said it wouldn't change the fluid in the pan. I always thought a tranny flush also changed the fluid in the pan?

I've already changed the filter and replaced what fluid was in the pan a few weeks ago. Which way is better regular flush, or back flush for the 700r4 tranny? Mine has 155k miles and I've owned it for 10 years and I've had the tranny flushed porbably 4-5 times. I know some of those were back flushes. The fluid is real dark as it's been a few years.

 

I personally don't believe in tranny flushes, as it can stir up debris that is sitting in a safe place in the tranny and send it into the valve body and areas it can cause problems. How is the fluid dark if you've had it flushed 4-5 times? Is it burnt? If your tranny is starting to fail I would leave the fluid alone and just run it. I do believe in dropping the pan and changing the filter once in a while on a newer trans with clean fluid. I've heard a lot of stories of people buying a higher milage car and going and getting a tranny flush and having it end up causing tranny problems a few days later. Just my 2 cents.

 

The flush should replace all the fluid period. to back flush the transmission cooler both lines would need to be disconnected from the radiator and the radiator flushed backwards and forwards and obviously not flush the trans at all but just the transmission bubble tank that is connected to the radiator. The flush where all the oil is changed by disconnecting one cooler line and installing the flush machine in line letting the transmission pump pump the trans oil is a very effective method. Trans fluid is a detergent type of oil and will do that when replaced so I could see some debris circulating but not enough to do damage. Trannys that are still good like new oil, trannys that are not still good don't like new oil--- and I don't mean the cross dressing type.

 

Yeah, I've heard the same thing, but I figured what the hell since it has been changed 5 times in the past 10 years. I think for the most part when people have problems right after a flush is because the car has 150k miles on the original fluid. I also wonder if putting cold fluid in a hot high mileage tranny could cause problems as well. I bought the car with 70k miles on it and had all the fluids changed as soon as I got it.

I don't know, but ever since I've owned it the tranny fluid always gets dark and smells burnt at some point. Whenever I had it in for service and a shop tech would tell me and show me the fluid is dark and burnt smelling, I'd tell them to change the tranny fluid. That would be every couple of years or so.

Last time I had it flushed was 3 years ago. I only put 10k miles a year on it. One of the times when I had it serviced 4 or so years ago, a tech told me the tranny fluid smelled burnt and that it needed rebuilt. I had them just change it, and it's been 4 years since.

I went ahead to the cheap place and had them change it. All they really do is unhook the tranny lines and connect them to a machine and idle the engine. The machine collects the old fluid while the machine gives the tranny new fluid. I could do the same thing in my driveway, but it is cold out and needed to be done.

And I asked about the back flush. The tech said that it doesn't really back flush, but draws and replaces the fluid at what ever rate the tranny runs on and every so often pushes the fluid back in the opposite direction for a short time. It probably isn't any different than any other place. But I went ahead and had it done. I will report back if it blows up.

 

that tech should have contacted cleo-because his crystal ball was way off. 4 years is a long way from "REBUILD IT NOW OR ELSE!". I've heard all the tricks and think that most of the time the customer "you" probably knows his car/truck best and whipping out the crystal ball isn't a good formula to do business. PROPS ON DISSING THE MAN.