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Discussion Starter #1
Has anyone ever heard of a Chevy Dealership Not being able to flush out the Allison transmission? I have 46,000 miles on my truck and I wanted to have the entire system flushed out. They told me that they do not have a unit that will withstand the pressures in the Allison. It would destroy their machine. I don't want to just drop the pan and change the filter, I want the whole system flushed out with new fluids. Anyone have any suggestions on how/where to have this done? If I did drop the pan and change the internal filter how much fluid would be needed to fill it back up compared to a complete flush? Would this void any warrenty issues?


Thanks, Jeff
 

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We have a machine from BG and the correct adapters from the Allison special tool kit. I do them almost daily with no trouble. Alot of it depends on the machine though. The BG machine uses the transmission pump to move the fluid, it has no pump of its own.
 

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FYI - in one of the other forums, the owner towed heavy loads with alot of wind resistance. He didn't use a machine to completely flush the fluid, but did change the remainder every 25k miles - transmission failed at around 120k miles (I think?)

Seems to me that any dealer that sells it to you should have the equipment necessary to properly service the truck.

Actually, I would be pissed that they are not set up to properly service the transmission. The fluid is supposed to be completely changed out at the service interval. My argument would be that since they are not properly set up to do the work that they should do what is necessary to "make it right".

Myself, if they didn't have a machine capable of flushing it, I would be insistent in asking that they change the fluid and filter twice to "get me there". I would drive the truck 500 miles between the fluid changes. I think they should pick up the incremental cost (over what it would cost to do it with the machine).


jeff

Edited by: dmax lover
 

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Discussion Starter #6
Maybe that is why they put a drain plug on the pan!!! I would personally like to have it completely changed and the only way to do that is to have it flushed. If you just drain and fill your slowly getting it done and it will cost a lot more.


dmaxalliTech, you mentioned having an Allison special tool kit. Do you have a part number or a way that I could get that information? I would like to bring this to the attention of our Chevy dealership/service department. I figure if I can bring them the information on how to get the equipment to service THEIR product, then maybe I can work it high enough in their management so they get it and start doing what THEIR manual says to do.



Jeff
 

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I guess this is sort of related. Above there was something about droping the pan and changing the internal filter? I didn't know there was an internal filter too. Is that right or did I just mis-understand? Edited by: Cruz_Man
 

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Discussion Starter #8
Cruz_Man, Yes, there is an internal filter as well. I have changed my external filter every 15,000 miles. And now I am at my next change and I wanted my tranny fluid changed and the only way I know how to do it completely is to flush it. Just draining it and filling it up again doesn't change all of it. What I was going to have them do is drop the pan and change the internal filter and then flush it while they were at it. Then as soon as I get home I would put another external filter on. I am capable of draining the pan and changing out the filters but the manual says to change the fluid as dmaxalliTech mentioned above and I don't have the machine to do it myself. I was hoping for a complete flush so every bit of fluid is changed out and not just 60% of it.
I guess I am stuck dropping the pan and doing it all myself. One good thing is I will save some $$$ for accessories later.



Now with my wifes Dodge Caravan, every spring I drop the pan and change the tranny filter and refill it with 5 quarts and it has 124,000 miles on it and still going strong. Ok, don't say anything, my wife is the one that wanted the dodge NOT me. She picked out the van and I picked out the motor since I was the one working on it. Now that she has her van, I got to pick MY truck.
 

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A machine is not needed to flush the Allison. All you have to do is disconnect the cooler return line and let the tranny pump out the old fluid per the Tranny Flush instructions on Hoot’s website which he posted above. I have used this method many times on previous trucks and on my Duramax. You have to be careful but it’s not hard.


More related info...


Allison Fluid Change


Edited by: jbplock
 

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Yes I have heard of a dealership saying they can't flush an Allison tranny. The GMC dealer I bought mine from (who also sells medium duty GMC trucks as well) said "their machine can't handle the capacity".
 

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I have heard that many times.. I think the trick is to use smaller adapters that will hook up to the lines, yet will be reduced small enough to slow the rate of exchange.


The allison special tool kit is J-44924


The flush adapters for the line are J-44835-1
 

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Discussion Starter #12
Thanks dmaxalliTech, are those parts only for the machine from BG? What kind of machine does the dealership normally have? Would they be compatable with their machine?


In the process posted on Hoot's page, I have a few questions. You mentioned not to run the tranny dry while pumping it out the "from cooler" line. How fast does this pump out? If I drop the pan and change the internal filter and bolt the pan back up and fill it up with Transynd + 2-3 quarts and start the motor. Will I have enough time to pour new transynd in the dipstick tube before it runs dry? How fast should I pour it in? I don't want to overfill the tranny while it is pumping. Also you said I would notice when the Dextron was done and the Transynd was coming out. What color is the Transynd? The Dextron that is in should be red right? Is the Transynd a synthetic fluid? How long can you run with this fluid? Where can I buy Transynd? And would I go through a complete 5 gallon bucket of Transynd? Sorry for all the questions, but I am new on the Allison and I don't want to destroy it.


Thanks, Jeff
 

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Discussion Starter #13
One more question. Is it better to change the fluid while the motor is warm or cold?


Thanks, Jeff
 

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these are the fittings i use, the black peice is actually part of the allison kit. the gold/chrome pieces are part of the BG flush machine. they use a quick connect to the machine hoses and work very good you can see in the female adapter how much restricted it gets and that keeps things under control. I am not sure of HOOT's procedure, but I have done them by unhooking the lines, start the truck until it starts spitting and sputtering the fluid. THis means the pan is getting low, add about 2 qts and run it out, then shut it down, remove pan and switch over filters. refill with clean Transynd. It is also a good time to install a deep sump pan if your interested. I think when the fluid has some heat in it, it would do a better job, but cold will work also. I am not sure the type of machine the dealer would have as they usually buy different. You can plan on using a full 5 gals for a complete flush. All the stuff you need is avail on my website. The fluid color change may only be apparent if your oem fluid has some miles on it, it may change to a slightly darker color, while the fresh Transynd will be bright red. Dont be alarmed when the Transynd turns orange with some miles on it, normal.
 

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You only need to run the engine about 1 minute to get the old fluid out and the new circulating. If you are going from Dex III to Transynd you can watch for the color change at the drain hose you put on the end of the line.


It's about 99% pure fluid purge using this method shown on Hoot's page. Several of us have done it. By the way, since you have the pan off, get the deep pan and the longer pickup screen while you are at it. Holds 2 extra qts. Only cost about $100-$125 for deep pan and long pickup screen, pretty cheap increase in capacity.


Good luck.


Edited by: Chevysrus
 

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I bought the deep pan kit from Dmaxallitech about a month ago. Good price and everything came quick.



The install went O K, but the flush is a two person job. The fluid comes out real fast. I wasted some of the transynd. I did not shut off the engine fast enough. All in all an easy job.
 

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Here is another option for the Allison from Mag-Hytec:


http://www.mag-hytec.com/


"We will have the Allison pan by mid December. It will sell for> $265.00 and will have a 10.5 capacity. I think we will come out about 3/4 of a qt. more than the Allison deep pan which is over a 3 qt. increase from the stock pan. Extra capacity does drop temps but the aluminum has a bigger effect on the temps. With the size of the pan I would expect to drop between 30 to 40 deg's."
 

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bigdog said:
I have a (stupid?) question about these deep pans. How does it affect the reading on the dipstick?




No matter how deep the pan the fluid is still the same depth from the valve body in the transmission, if you follow what I am saying
.


The fluid capacity is more the fill height is the same.


T
NY
 
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