A FEW ??'s Before I Flush!!

[Luis]

I'm getting ready to Flush the Allison and replace fluid with AMSOIL Torque-Drive synthetic transmission fluid. I've read several post that explain the flushing process and they are quite detailed. However, I have a few more questions; After I drain/drop/clean/replace/re-fill the pan, disconnect the "From Cooler" line start truck and pump out six quarts of trans fluid, Will this six quarts SET any codes for low fluid in the trans? When I start the truck to pump out the fluid do I put the truck in NEUTRAL or leave in PARK?

Thanks in advance.....

[DmaxMaverick]

Leave it in Park. The only difference, functionally, between P and N is the engagement of the parking pawl. Don't get the engine RPM's above idle.

It may throw a code if/when the pump cavitates (sucks air). No big deal. After all is done, it will purge the air and the code will go away after a couple start cycles. No problems will result from it.

[Luis]

Thanks DMAX Maveric! I tend to worry about setting codes etc. Tranny is over warranty mileage plus I wasn't sure if cavitaion would hurt the pump etc. I know (according to other post) it only take approx 30 seconds to pump out the remaing fluid but wanted to make sure. Thanks once again!....Luis

[Lone Eagle]

There is absolutely no reason to pump the pan dry. Drain the pan and refill. I used a clear 2 1/2 gallon container marked at the one gallon level. I had my wife start the truck. I had her stop it when it hit my mark. I ended up using 13 quarts. Good luck. Later! Frank

[Inspector]

One more thing, use Transynd instead of Amsoil.
Denny

[DmaxMaverick]

Inspector

Because????

[Inspector]

Nothing against Amsoil but I am of the opinion that if Allison has done all the testing on Transynd and recommends it for there real big transmissions then I'll go with that. Just my personal opinion. I use Amsoil in my 03 and in the old 93 and like it very much. I believe that the Transynd is tiny bit cheaper as well.
Don't want to ruffle any feathers its just my opinion.
Denny

[DaveRuane]

Approximately how long did it take to pump the 13 quarts? Last time I did this it took less than a minute. Is that about right?

I am changing back to Transynd after running Mobil 1 Synthetic ATF for a year. No problems but I got my hands on a 5-gallon bucket of Transynd. I was going to:

*Drain, drop and clean pan
*Refill with about 1.75 gallons
*Pump out of the "From Cooler" line
*Refill displaced amount
*Check fluid level for a week.

*Run for a couple of weeks
*Then drain, and refill pan with more Transynd

Does this sound like a good plan to transition back to Transynd? I know I might have to do the last two steps multiple times.

[DmaxMaverick]

DaveRuane

With your procedure, you might as well just do a drain and fill without pulling the return line. Unless you do a complete flush, you will be mixing old with new forever. You will be wasting a lot of Transynd. Although, each time the fluid will have more Transynd, it will be much less than a complete flush. It would take a long time to reach 90% + replacement. Even then, you would have old Transynd mixing with new Transynd.

If you intend to "replace" the existing fluid, a complete flush is the only option.

[DaveRuane]

OK,what is a "Complete Flush" then? I thought by flushing from the "from Cooler" line I was getting as close to a complete flush as possible. Is there a procedure for a "complete Flush"?

[DmaxMaverick]

Perhaps I misunderstood you.

By your steps, it sounds like you are only replacing 1.75 gals, and moving on until you do it again in a couple weeks. If this step is repeated (in one session) until the old fluid is out, my apologies, and please disregard my previous statement. When you "pump" out the old fluid and replace it with the new, be sure that you get a clean stream of new fluid out of the return line before you stop the process. Elsewise, you will still have a considerable amount of old fluid left.

Also, it is not necessary to drop the pan. My brother did this after about 15K on his '02, and we found that what was left after the drain wasn't worth worrying about. It is also not necessary to replace the internal filter, as Allison states only at overhaul. It won't hurt to do it, but it's probably wasted time and effort.

[DaveRuane]

OK, I drained & dropped the pan, cleaned it all up, cleaned the magnet & installed a new spin-on filter, reinstalled pan, filled with about 2gals of Transynd, pumped about 1.5 gals out of the "From Cooler" line, reinstalled line, refilled to the cold level with Transynd, drove around and topped it off. My objective is to further dilute the previous ATF that was in there before I started since I know the above process didn't replace 100% of it. How much driving is required before I have a homogenous mix of old & new in the pan again? Is it a couple of hours of driving? or days? I would like to finish off the rest of my new Transynd to the best benefit by draining the pan, and refilling with more fresh.

[DmaxMaverick]

OK

Guess I didn't misunderstand you.

At the rate you are going now, you will never achieve a complete replacement.

You are replacing less than 50% of the fluid at each session. Do the math.

The only way to replace all of the fluid (all meaning as much as you possibly can without dissassembling the tranny) is to do the complete flush as described on the forum. It has to be done in one session to be effective. Any other way is wasting fluid and time, and it will not be completely replaced.

Don't get me wrong here. I am not trying to talk you into doing something you apparently don't understand. My response is intended to prevent another person considering this to take the more practical route.

It's your truck. Do as you please.

[Luis]

UPDATE!!!! Sorry I haven't been following this follow up closley, I've been very busy....With that last week I had a day off last week so I was going to flush the trans the next morning...That evening I received a call from my friend who owns two AAMCO shops. He had received the fitting to fit my trans lines. Since it was raining and calling for rain the next day I decided to have him do the flush. Took the truck to the shop and was done 35 minutes later. Returned home with approximately six quarts of Torque-Drive ATF left over. His machine did all the measuring and separated the new from old fluid. after flush replaced the spin on filter. Machine connected to cooler line at top of radiator and was passive, meaning he had to start the truck to pump old fluid out. I haven't (knock on wood) noticed any leaks or problems from the flush. After this towing season I will drain/remove-clean/replace pan and spin on filter and refill with left over ATF plus any additional qts. needed. Overall: satisfied wit using AAMCO flush system to replace fluid. BTW it cost me one hour labor, which as it turned out was worth it because the weather and helper had to go to workthat morning and wasn't available. Thanks to all once again for all the great advice and opinions etc.