Hi,

I have a ’94 Ford Aerostar 4.0. The poster “96_4wdr” says you need 11 quarts of transmission fluid to do a “full 11 qt gentle flush”. See here: https://www.ford-trucks.com/forums/6...neup-tips.html

Is this true? What is the easiest way to perform a transmission flush at home or is it not practical to do this at home? I bought 5 liters of Mobil 1 Synthetic ATF. <O</O

The poster “b2trausch” says you need three gallons. See here: https://www.ford-trucks.com/forums/5...y-at-home.html

That’s a lot of Mobil 1 Synthetic ATF!

Which end of the ATF cooler do I disconnect to bleed?
Do I need to install a filter?
Do I need to drop the pan?
Do I need a new modulator? (it has 70,000 miles)

Much thanks!

 

Ok, first, you do need to disconnect the return line from the cooler.

Secondly, you need to replace the filter. Use a quality brand such as Purolator or Wix, no Fram.

Yes, you need to drop the pan. The way I prefer is to drop it before flushing it, replace the filter, remove all the gunk from the pan and judge by the amounts and type of material in the pan, the likely condition of the tranny. Should be mostly wear materials, maybe some metallic dust. Any shavings of metal means the tranny is starting to wear out and fail.

The modulator does not have to be replaced, however, it is not a bad move to prevent its failure. The 4.0L has an extra heat shield to prevent excessive heat from damaging it.

Now lastly, I have never done this myself, though I am familiar with what needs to be done. I have a shop I trust, that does exactly what I ask them regarding the matter. I will probably have it serviced this comming week, been about 20,000 miles since its last flush. It will get an inspection of the materials in the pan and replaced the ATF with Royal Purple full synthetic.

 

https://www.ford-trucks.com/forums/5...y-at-home.html

#7

 

Thanks guys!

 

I just did my 96 a few weeks ago. I disconnected one of the lines from the cooler and fluid squirted out of both the line and the hose I disconnected from it. So... I ran clear tubing from both and ran them into a clear gallon jug.

The clear tubing was great because I could see what/when it was flowing. Also, the clear just let me know how much was purged.

I shoved the lines into the jug and started the motor. When it purged about a half gallon I stopped and added a half gallon. I repeated until nice clean fluid was coming back out.

Next, I dropped the pan, and changed the filter and gasket (Yes, that wastes some of your new fluid but oh well). Then I topped off the fluid again.

All together I swapped out exactly 3 gallons. When the clear jug was full i would pour it into one of the black 1 gallon ATF fluid jugs.

It was a very messy process, I had a giant pan under the cooler to catch drips and I had the jugs sitting in another large pan because crap gets everywhere!

For pans I used some of those low profile plastic totes, about 4" tall 2'x1.5', worked great.

Now I know that my van has clean blood in the tranny. Also, by purging before changing the filter I feel like I didn't push crappy fluid through my new filter.

I wanted to install a drain plug in my tranny pan for next time but I couldn't find one.

I used the regular autozone buy-it-by-the-gallon stuff. Also, I laid out my new gasket on a flat surface about a week in advance so when the time came it was nice and flat.

 

use a neoprene gasket, comes with the premium filter kits
far easier to put on than a cork, no breakage and can be reused

make sure both O rings are on neck spouts of filter before inserting into tranny and that both old O rings came out when old filter removed

scrap and wash perfectly clean the pan gasket and tranny gasket surfaces, use toulene or acetone, wear gloves and goggles
then a light coating of Permatex Super 300 Tack

there are 2 different mount types of auto tranny filters for Aero, 1 for RWD and 1 for AWD...make sure to get correct type
screen filter is the best for max ATF lube flow

doesn't matter whether filter is changed first or after flush....not all ATF put out by pump goes to front cooler directly....some goes from pump thru tranny clutches and servos and then dumps directly into pan

put an inline micron filter in cooler lines up front

 

What can I say, you guys are great, thanks so much!

 

I think this gentle flush business done at dealerships is nothing but a rip off I think.It was designed to reduce the labor involved in the traditional fluid and filter change and to reduce the warranty payout as part of the free maintenence schedules promoted by the car companies. I just replace the pan filter and add semi synthetic Coastal trans fluid from Autozone that meets MerconV specs. I also have disconnected the factory trans cooler/rad setup. I now use a heavy duty trans cooler mounted in front of the rad. The shearing and continual heating cycles certainly degrade any oil but the semi and full synthetics offer better stability over the operating temp ranges.

 

I am not sure what you mean by “gentle flush”, does that method not use the flushing machine as found at the transmission lube shops?

How exactly do you do the transmission fluid change?

 

the gentle flush means that the transmission flushes itself. The power flush that transmission shops advertise uses a machine to flush it out. These machines may damage some transmissions, especially the A4LD, since they can disturb the friction material and cause it to be picked up by the torque converter and other components.

 

Since I have a 1994 2WD Aerostar 4.0 are you recommending against the power flush as done at the transmissions shops and that I should do a gentle flush at home?

 

As stated earlier and with other follow ups from the other posters here, flushing relies on the cleanliness of the lube shop.Many people do flushes when trans problems arise thinking what is a $100 or so if it keeps the trans going. This introduces burnt and contaminated fluids into the machine system. Yes they are supposed to clean the lines etc. after every use (really)!!! before the next vehicle. Trans filter and 4qts fluid is all you need. I have 225k on 97 Aero and this is its 4th trans service. Use Coastal semi syn at Autozone $3 and change a qt.

 

Change all 11 quarts. Some people on this forum have been able to keep their originl trannies going for over 400,000 miles. You need to flush the cooler lines, and torque converter. You need a new filter and 12 quarts of fluid. Doing a 4 quart flush does not remove any of the old fluid from the torque converter of the cooler lines. Changing 4 quarts at a time is better than nothing, but you can gentle flush it yourself. What the transmission shops do is not a gentle flush. The gentle flush does not require any special tools. I don't think you understand the difference between a power flush and a gentle flush. A power flush is where they use a machine to pump new fluid in and the old fluid out. These machines have probably killed more trannies than they saved. If they are properly maintained that may work well for some trannies, but they cause pressure where it was not meant to be and will kick up friction material and gunk and force it into the torque converter and the small passages in the valve body, plugging or restricting the passages. A gentle flush however does not reuse any old fluid and does not cause any pressure build up where it was not meant to be. Follow the links given above for the procedure.

To summarize: A simple fluid change will not adequatly protect the transmission. Doing this is like draining your oil through the filter without ever removing the drain plug. It will leave a lot of old fluid in there and your new fluid is immediately contaminated. A gentle flush performed as shown in the above links is the proper way to do it. Perform the flush, then drop the pan and replace the filter.

 

Thanks so much for the superb clarifications, a full 11 quart gentle flush it will be!

 

ChumlyChumly,

The only thing that I can add to the procedure that the above posters have already stated is that I get someone to help me to start and stop the engine while I do all of the "dirty work". I have a five gallon jug that my old fluid drains into which keeps the mess to a minimum. The clear hose is very helpful to observe the color of the fluid coming out.

The 3 gallons that I spoke of is because I flush a little longer after I see the fluid color change just because I want to make sure I get as much of the old fluid that I can. I haven't used synthetic fluid in my tranny, and I've got 265K on the original.

Yes change the filter. I change mine before I flush. I'm not worried if any of the old fluid passes through a new filter. It's been getting filtered all the time anyway, so it is essentially clean fluid. The chances of any "gunk" contaminating the new fluid is minimal.

Sorry I didn't respond to your request sooner, I've been at work between 11-16 hours this week, and haven't been on my home computer much.

Let us know how it goes.