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9,792 Posts
Discussion Starter · #1 ·
There are two lines on the passenger's side of the transmission up front near
the converter; the lower one is the "To Cooler" line and the upper one is the
"From Cooler" line. If you disconnect the "From Cooler" line from the transmission
you can put it in a bucket and flush to your heart's content.

In case you haven't seen the Jiffy-Tite style connector before: Slide back the
plastic cover over the c-clip-shaped spring, then use a small screwdriver to
pop the spring out of its groove.
because those springs just love to go flying off into some dark hole where
you'll never find it. Once the spring is out,just pull and wiggle on the line
until it comes out of the fitting. As soon as you have the line out you can put
the spring back into its groove so you don't lose it - the line will snap right
back into place when you're done, even with the spring there.
Be careful not to damage the o-rings when re-installing.

A few other tips for your pan swap...
When you're removing the old suction filter: if the seal stays in the bore, don't use a screwdriver
to pry it out. Just wipe off the neck of the filter, wipe out the seal, and reinstall the filter.
Cock it sideways a bit and pull down again - the seal should come out with it.>

Your refill quantity will be 10.5 quarts or roughly 2.5 gallons. This
is with the deep pan, and does not include the cooler lines. The torque
converter holds roughly 4.5 quarts in addition to the 10.5 quarts. Obviously
this means you will have a mixture of TranSynd and Dexron. The two fluids
are compatible.

I bought a 5 gal pail of Transynd ($125) and poured two quarts in clean
containers just in case I needed to add any in the future. The remaining
4.5 gal went through the tranny - start the engine, run a few quarts out,
shut off the engine, add more Transynd and repeat until it was all in.
Lucked out that my final check was right on the correct fill level
(checked HOT as per the manuals).

If you refill with Transynd as I did, you will have about 58% Transynd.
After the second fluid change using Transynd, you will have about 80%
and over 90% at the third change. If you plan on switching to TranSynd I
recommend you buy 3 Gallons and pull the "From Cooler" line loose from
the transmission (install a short hose into a bucket) and start the truck
up to flush (the majority) the Dexron 2 out... I over fill the pan by 2-3
quarts when I'm doing this...

You "feed and bleed" , *DO NOT* pump your tranny dry!! You install
your filters, pans and whatnots, fill her up to the "cold" mark with new
fluid. Then hook up your flush hose and also feed new fluid down the
dipstick hole while you are pumping. After pumping about 2-1/2 to 3 gallons,
stop, reconnect the flush line, fill back up to the cold mark with new
fluid. Then start it up and work your way through all the gears
(holding the brakes), pausing for a few seconds in each selection.
Take her out for a spin around the block and drive for about 15-3O minutes.
Then come back and do the through-the-gears routine again before winding up
in Park and while still idling check for fluid at the "Hot" level. Adjust
as necessary and you are set!

No.. What I'm saying is after you have drained the fluid and replaced
the spin-on filter you can remove the "From Cooler" line and install
a short piece of hose into a bucket... From that point I hope you measured
about how much fluid you took out of the trans including the filter...
Now install the same amount +2-3 more quarts and start the truck up
(it may take a few seconds for the fluid to start coming out so don't
be alarmed if it does this) You should be able to tell when the Dexron III
stops and the TranSynd starts. At that point cut the
truck off and reinstall the Cooler Line.. Now crank the truck back up
(check for leaks) and place it in Drive-Neutral-Reverse then back to PARK..
Do this a few times then check the Fluid level.. It should be on the "COLD FULL"
line if not add Fluid until.. Then as idle chatter said, drive it around
to get the trans temp up then check to see if it's at the HOT FULL mark
if not add fluid..

Pan bolt torque - 18-21 ft-lbs.
Drain plug torque - 25 ft-lbs.

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22 Posts
Talked to a mechanic at an Allison service center today who said they were taught to drain, put new spin-on on, fill, run for a few minutes (shift), drain again, refill. This was what they did whenever someone came in for a trans fluid change on a 1000. He said they have a flush unit but this was the procedure they were taught in Allison school.

Good enough?

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13 Posts
I followed this procedure to a T last weekend when changing from Dex3 to Transynd. I was a little nervous. I am very mechanically capable, but have never flushed a tranny before. Doing major work on soemthing 20 years old and worth a couple grand is one thing. Screwing with something worth $40k and less than a year old is another story as far as comfort goes!

Anyway, worked great. Really took my time cleaning everything real good and took me about 2 hours. I got a 5 gallon drum of Transynd. One thing that added time was setting up containers into which to transfer the fluid. I used some OLD Sunny D OJ containers. Measured out and marked exactly 1 qt and 2 qts on the containers. Transferred the fluid from the 5 gallong container to these to pour into the dipstick. This helped me know exactly what was going in. I then used some old Rotella T gallon containers to measure what had been removed and emptied into my drain pain.

I did not replace my tranny pan. The guy at the allison dealership said that he did not believe the extra capacity (as little as it is) was worth the money. According to him, if you want to reduce the heat in the tranny, you would be better off adding a second cooler with a bypass valve for winter time than getting the deeper pan. If you are NOT replacing the pan, it is still imperative to drop it. Due to the indention of the drain plug, there is quite a bit of fluid that gets trapped in the pan that will never drain. In addition, for a true flush, you must change the internal filter.

As far as how fast the fluid drains, that can vary. It would REALLY be better to get someone to start it up for you, even if it is a neighbor or soemone. Won't take more than 5 minutes of their time. If you r truck has been sitting for a while, it could take a bit. I started my project of draining and dropping the pan. But I had to stop to go to my setpson's basketball game before I had the chance to reassemble and start the flush procedure. Truck had been sitting ivernight in the driveway. Fluid had been drained from the pan for about 4 hours. When the engine was first started, it took 20 seconds or so before it started flowing out of the cooler line. Once it did, it came at a pretty good clip. Also note that AFTER the engine is STOPPED, fluid will continue to drain for a couple of seconds. So if you are getting close to the top of your container, stop with a decent cushion.

Other than that, it was a simple process. Be sure to cycle the gears when doing the final cold check to fill up all the hydraulics of the tranny. I failed to do this and was a lot lower than I should have been when doing a warm check. Luckily I got it much closer and was able to just top it off during the hot check.

Oh yeah, it was nice having the extra Transynd to go ahead and replace the fluid in the tcase (very easy) and have 2 qts left over for pre-filling the spin on filter at later changes.

I also took the opportunity to swap in Mobil 1 75W-90 in both pumpkins. Its nice to know I don't have to touch a fluid other than motor oil in this rig for a LONG, LONG time!

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69 Posts
ok, being a newb to this forum AND to the Dmax/Ally club, im looking at almost 20K in mileage on my 03 2500. Is it time for a trans. fluid/filter change, and what is this transynd stuff???

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13 Posts
TClark said:
ok, being a newb to this forum AND to the Dmax/Ally club, im looking at almost 20K in mileage on my 03 2500. Is it time for a trans. fluid/filter change, and what is this transynd stuff???

First off, it is recommended by GM and Allison that you change the internal filter and fluid in the tranny at or around 25k miles. The GM fluid is Dexron 3, the latest version of the same tranny fluid GM has been using for decades.

Transynd is a synthetic fluid that is recommended by Allison. As a matter of fact, with "normal" use, you can go for 100k miles on Transynd without another fluid change. The fluid is compatible with Dex3, so you can mic them, but the 100k deal isn't valid until you have at least 90% saturation of Transynd. Your tranny pan holds around 7.5 qts, yet the entire system holds around 12.5 qts (cooler, lines, torque converter). So simply draining the pain and refilling with Transynd will not get you to the 90% level. It will take several fluid changes before this occurs.

Hence, many use the flush methid described above to "completely" flush the old Dex3 out of the transmission's hydraulic system. It is a fast way to achieve the 90% level. From talking with the Allison rep, he also states I should see about a 15-20* temp drop by using Transynd over Dex3.

Transynd is usually only available from your Allison dealer and runs around $30 or so a gallon.

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69 Posts
Thanks Brian.

Thats the kind of info i was looking for. Now i guess i need to find an Allison dealer in the Conyers/Atlanta area so i can buy some.

Anyone out there have any connections on how i can find a dealer?

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10,850 Posts
Sparky, side note on your comment on the deep pan...
I have to agree your likely not gonna notice anything when switching to it, but I feel that the extra capacity is peace of mind... More oil the better in my opinion. Since your already buying a filter anyways, the only additional cost is the pan it self and you already will have the old pan off....

Tclark, you can do a search on Allisons website for dealers or you can have it shipped to your door from here

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13 Posts
dmaxalliTech said:
Sparky, side note on your comment on the deep pan...
I have to agree your likely not gonna notice anything when switching to it, but I feel that the extra capacity is peace of mind... More oil the better in my opinion. Since your already buying a filter anyways, the only additional cost is the pan it self and you already will have the old pan off....

I do agree with you. I have always run deep, finned pans on my 700s. I just didn't want anyone to think that (a) you had to get the deeper pan for use with Transynd or that (b) you would see any major difference in the deep versus stock pans regarding performance.

But, note to everyone, if you do get the deeper pan DON'T FORGET THE DEEPER FILTER/PICKUP. Had a friend one time that ran a deep pan on his 700 with a stock filter. Needless to say he thought he had plenty of fluid still in the pan when he was runnign low one time, and actually he did. But he wasn't sucking any into the tranny!!

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2,897 Posts
Changed my trans fluid to Transynd yesterday in my new Level 3 Suncoast tranny and all went well with the help of Steeltech and Hoot's instructions.

I drained 2 gallons from the pan and filter, and another 2 gallons from the upper cooler return line.

I installed a Mag-Hytec deep finned pan, new filters and put 5 gallons back in to bring it up to the right level.

I'll see in the warmer days ahead if the tranny stays any cooler. But just having and extra gallon of fluid circulating can't do any harm.

Thx again to all for these how-to articles and the pictures that go along with them, they sure make the jobs a LOT easier.

Bye Diesel Dragon
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