Transmission Flush?

[QIKSILVR]

Who's right?  Time to change the tanny fluid in my 99 Silverado. Called the dealer.  They recomended power flush, drop the pan and replace the filter.  Called a couple of tranny shops and they said that a power flush is a bad idea?  They recommend drop the pan and just change the filter.  No powerflush.  They said that the cleaner in the power flush will hurt things.(seals)  Who's right?  I know I've read that alot of people are having thier tranny power flushed.  What's the deal.  What's your take?  Maybe there's a transmission expert out there who can clear this up.  Thanks!

[americanmuscleman]

I've had my tranny flushed every 20k since my truck was new (112k on it now).  I've never had any trouble with it, and my transmission shifts like it was new.  

[BlueRado]

Who's right?  Time to change the tanny fluid in my 99 Silverado. Called the dealer.  They recomended power flush, drop the pan and replace the filter.  Called a couple of tranny shops and they said that a power flush is a bad idea?  They recommend drop the pan and just change the filter.  No powerflush.  They said that the cleaner in the power flush will hurt things.(seals)  Who's right?  I know I've read that alot of people are having thier tranny power flushed.  What's the deal.  What's your take?  Maybe there's a transmission expert out there who can clear this up.  Thanks!

I could be wrong here, but sounds like hogwash - the tranny shop probably didn't have a power flusher and didn't want to lose your business.  

 

BTW, welcome to the site and forum!! :thumb:

[robsawatsky]

From everything I've ever seen a power-flush on an auto tranny doesn't involve any chemicals or cleaners other than tranny fluid.  They just use a pump to force all of the old fluid out and replace it with new.

 

Just draining from the pan will leave a lot of fluid in the innards of the tranny.

[QIKSILVR]

Thanks for the info.  I found out that as long as they just flush the tanny with fluid and no cleaners I'll be fine.  While dropping the pan to change the filter of course.  Thanks again

[MarkD]

...just wanted to lend my support to the powerflush, then pan and filter method.

 

I would have to agree with bluerado on the reason behind the tranny shop recommendation. 's

[Black02Silverado]

From everything I've ever seen a power-flush on an auto tranny doesn't involve any chemicals or cleaners other than tranny fluid.  They just use a pump to force all of the old fluid out and replace it with new.

 

Just draining from the pan will leave a lot of fluid in the innards of the tranny.

Just wanted to let everyone know that it really isn't a powerflush. There is no power to it other than the actual transmittion doing all the work. If someone hooked up a machine that actually pumped, (FORCED) the fluid into the tranny I would stay clear of them.

 

What they do is hook up a machine that has a compartment in  it that holds the new fluid. They then hook it up to the oil cooler lines that come from the transmittion. The machine is in bypass while the vehicle is started and warming up the transmittion. This just acts like the cooler and no new fluid is transfered. After a couple of minutes they turn on the valve that allows the fresh fluid into the transmittion.

 

The old fluid is pumped out and into the baffle that is located in a seperate bladder on top of the fresh fluid. What this does is help push the fresh fluid out and into the transmittion but keeps the old from mixing with the new. The pump in the transmittion does all the work.

 

That way there isn't any excessive preasure anywhere in the system than wouldn't be normally.  Now you have to be aware that some shops will put a conditioner in before they do the flush and let it run during the warm up phase. It is up to you if you want it or not. Personally I don't see the need if you keep it changed on a regular basis. It is just a good thing to change the fluid out often and keep it fresh.

 

I look at it this way. If you change the filter and fluid every 15k then a flush is not really needed but if you let it go twice as long or even longer than you want to get the old fluid out and the fresh fluid in. Heavy use from hauling and towing really heats up the tranny and the maintenance schedule needs to be stepped up to help preserve the life of it.

 

One other way to help it live longer is to install a tranny cooler and to run synthetic. The charracteristics of synthetic keep it cleaner and resist breakdown under extreme heat as well as flow better in cold weather than its pretroleum counter part.

 

I used 16qts to flush my truck. That way I was sure it was completely swapped out old with the new. Just dropping the pan only gets 4 to 5 qts depending on the type of transmittion.

 

[robsawatsky]

Right of course.  It is just the tranny itself that draws the new fluid in and pumps the old stuff out.  I had this erroneous mental picture of what happened last time I had my tranny serviced.

 

I never let anyone put cleaners, chemicals, flushes, in my tranny, crankcase or rad when changing fluids.  You never know what kind of incompatible crap they are putting in there.

[dougmac]

I just did this last night at home without a power-flushing machine. This is the way that I have changed the fluid in automatics for years.

 

First I drained the pan, removed it and changed the filter. This was the hard part on my truck because the shift cable bracket and exhaust had to be removed.

 

I put all of the fluid that came out of the transmission in a bucket that was marked in quarts. I put the same amount of fluid back in plus four quarts. Basically overfilling it by four quarts.

 

Then I removed the grill so that I could get to the auxiliary cooler and removed the line that came from radiator. Place a hose over the line and put the other end of the hose in a gallon milk jug. Started the truck HOLDING IT WITH THE BRAKES and immediately put it in drive filling the milk jug with fluid. Shut it off when the jug was full.

 

Added another four quarts. Replaced the jug with an empty one. Started it and immediately put it in drive until that jug was full. Hooked the line back up to the cooler, put the grill back in, topped the fluid off and took her for a test drive.

 

You want to be careful if you use this method because the return fluid from the cooler goes to the lube circuit of the transmission. When you capture the fluid and have none returning, you have no fluid going to the lube circuit. This will not hurt the transmission if it is not turning. That is why it is essential that you place it in gear immediately after starting it and do not allow it to run out of gear with the cooler line disconnected. When it is in gear and the truck is not moving, essentially the only thing that is turning is the converter and pump. They both have plenty of oil going through them.

:thumb:

 

Doug