Auto Tranny Flush

As some here know Im a PERFECTIONIST (or a NUT more like it) when it come to preventive maintenance on my RV sooooooooooo I plan to replace the pan with one of those bigger (adds 3 quarts n has internal cooling tubes) cooler types and change to Synthetic Fluid. It already has a front aux radiator type cooler but Im headed West next summer to the mountains and heat is its worst enemy I figure.

Butttttttttt when I drop the pan to install the new one that wont flush n drain the fluid in the Torque Converter right??????? My buddy has one of those professional drain n flush n fill machines and he could flush n refill with synthetic but Id like to change the pan before I drive it over there.

Any way I could drain the torque converter here at home without too much trouble?? Im not into heavy under the RV work anymore Im gettin too dern old for that lol Its a 4L80E GM 4 speed auto overdrive tranny behind a 454.

Ol John T NOT a tranny kinda guy

So your going to drop the pan and then refill just to drive it to your friends shop to drain it all again and refill? why not just drop it off at your friends shop - tell him what you want done and spread some wealth around? I've always thought that people that drove those monsters didn't have to worry about the small things (like bills or gas)! Just kidding! please don't slam me back.

Forcing air through the cooler lines will push at least half of the mineral oil from the torque converter.

I dunno about the Chevy transmission. The Ford C-6 torque converters have a drain plug in them. Remove the plug and the converter drains. Interesting thing is that it somehow senses how big a drain pan you have under it, and always manages to drain 2 quarts more than the capacity of the pan.

When you fit the new pan-see if it has a drain plug option. Then when you do the engine oil change you can also change 1/2 the tranny fluid. This was common on commercial fleet vehicles, cabs, police cars, and my old postal Jeep DJ5 had one for its powerglide. Really extends transmission life in rough service. RN

When i changed the fluid to synthentic in my 01 duramax with the allison tranny i went to a local allison shop.They told me to change the filter,unhook the cooler return line at the tranny.Then start the engine and let a gallon pump out of the tranny.Then put a gallon of new oil into the tranny filler hole.Repeat this 3 times and all the oil will be changed.I could see the color change in the oil coming out when the synthentic started coming through.It changes the oil in the cooler and tranny lines also.

your plan sounds like a good plan to me,,, I like to flush then suck the fluid out of the pan and change the filter then put the fluid I sucked out back in,,, On the professional repair sites they recommend to first change the filter then flush,,, i don't understand it but that's the recommended practice.

The more fresh you run threw the trans the more likely you will get most of the old out,,, go for it .

Amsoil had and may still have a instructions on how to flush the system. I"ve done it several times. You need two people to do this. First remove the pan, put in a new filter, bolt the pan back up and refill the pan to full on the dipstick. Next go to the line that brings the fluid to the cooler or radiator and take that line off. Add a hose to it so you can catch the fluid that"ll come out when you start the engine. Then have more new fluid ready to pour in while the old oil is being pumped out. Once the old oil starts watch for the color change. When you see the new fluid come out stop the engine and top off the transmission to the full mark or if you have to much still in there just pump a little more out.

If the oil is slow coming out set the brakes and put the transmission in drive or reverse and it"ll come out faster. Can"t remember which models had to be in drive.

Amsoil use to have fittings just for this and you could take the return line off the radiator cooler and flush that too.

You may waste a quart but if the old oil is dark you can see the new oil easy and just stop the engine then. This also flushes out the convertor too.

Good idea on the synthetic fluid John T.Now does that rig have an external cooler for the tranny?If not that is a great option to help extend the life of an Automatic transmisson.Those overdrive rebuilds are not cheap by any means.Lots of truck supply sites carry external tranny coolers.

Used to work at a GM dealer. What the techs did on the cars and light trucks was to pull the pan and suction filter. Then you stick a hose up on where the filter goes. you may need to cut off and use part of the old filter stem ? Then stick this hose down into a jug of NEW fluid. Keep it up as short as you can. Then start the engine and watch it get sucked up. Old will run out and down everywhere. They had a 55 barrel cut in half lengthwise as a catch pan. That's how they flushed them.

I just completed this operation on my Ford F150. I got most of the old oil out went through 14 qts. I am getting go the point where it is real hard to lay on my back and work looking up. I guess at 67 some things will be more difficult. I will continue to do my own repairs, and maintenance as long as the good Lord lets me. stan

John just google flushing oil in auto transmission. Lots of good information

Bob

I would 2nd that AMSOIL is a very good transmission fluid and has very good synthetic oils (the best actually). However, It may be a bit expensive to use to flush with though. Maybe do a flush like others have mentioned with a good/cheaper fluid and then drain and put AMSOIL in. You may as well go synthetic in the engine too. It will run cooler and the synthetics won't break down under the heat.

Good luck. enjoy your trip.