Has anyone tried to drain their torqe converter on a fluid change on these allison transmissions?

chucky

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Was wondering the procedure to drain the converter when i switch over to transynd fluid and to fill the transmission with the 12 gallons before i start the engine and if so will that mess the converter up if its empty when it starts . Any ideas ?
 

simp5782

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Was wondering the procedure to drain the converter when i switch over to transynd fluid and to fill the transmission with the 12 gallons before i start the engine and if so will that mess the converter up if its empty when it starts . Any ideas ?

You wont be able to put but so much in the transmission, the pump will have to push it to the torque converter then add to the drain pan as it gets pumped into the converter. Won't hurt it at idle since there is no pressure in neutral.


Better to use a drill pump and hook to the transmission lines. Use the drill pump to pump the transyn in to the transmission. Use the other flow line hooked to a bucket to drain the old. Let the transmission pump do the work getting it out. Stop pumping transyn into the transmission when the fluid turns the bright red color. No different than doing a transmission flush. Just without the machine

Drill pumps are found at home depot very cheaply

Lines are usually removed at the heat exchanger and flush it with cooler cleaner while its disconnected
 
Last edited:

chucky

Active member
221
145
43
Location
TN.
You wont be able to put but so much in the transmission, the pump will have to push it to the torque converter then add to the drain pan as it gets pumped into the converter. Won't hurt it at idle since there is no pressure in neutral.


Better to use a drill pump and hook to the transmission lines. Use the drill pump to pump the transyn in to the transmission. Use the other flow line hooked to a bucket to drain the old. Let the transmission pump do the work getting it out. Stop pumping transyn into the transmission when the fluid turns the bright red color. No different than doing a transmission flush. Just without the machine

Drill pumps are found at home depot very cheaply

Lines are usually removed at the heat exchanger and flush it with cooler cleaner while its disconnected
What are you calling the heat exchanger in laymens term the black round resivour under the fan shrould? and how do i know which way im pushing the fluid/
 

chucky

Active member
221
145
43
Location
TN.
You wont be able to put but so much in the transmission, the pump will have to push it to the torque converter then add to the drain pan as it gets pumped into the converter. Won't hurt it at idle since there is no pressure in neutral.


Better to use a drill pump and hook to the transmission lines. Use the drill pump to pump the transyn in to the transmission. Use the other flow line hooked to a bucket to drain the old. Let the transmission pump do the work getting it out. Stop pumping transyn into the transmission when the fluid turns the bright red color. No different than doing a transmission flush. Just without the machine

Drill pumps are found at home depot very cheaply

Lines are usually removed at the heat exchanger and flush it with cooler cleaner while its disconnected
Oh and another question when do i swap the filters in the pan after the flush i assume? im not thinking the pan is empty when you drop the filters i cant remeber if they just droped the bolts over the filter and you just lost the fluid around the filters i should have paid more attension when my bus was in the air getting serviced its been a few years
 

simp5782

Feo, Fuerte y Formal
Supporting Vendor
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113
Location
Memphis, TN
Yes. Its a transmission cooler. or heat exchanger being that it is not an air to air cooler.

5 ton FMTVs have the air to air cooler to supplement the heat exchanger to the engine coolant doesn't have to work so hard to keep the coolant temp in check. If it was a 5 ton truck you could simply hook in on the air to air unit to flush everything

If you can chase the hose route easy enough the lowest line on the transmission is always the pressure out line with the top line being the return

Or if you can't chase hoses. Then remove both at the exhanger and place in a bucket. Start the truck for a second and shut down and see which bucket has fluid vs none.

I always flush then change the filter in the pan. Drain the pan of the fresh fluid and Filter what was drained from the pan thru a t-shirt or other small media. Or thru a supplement spin on system.

I have filter housing with a hose I can attach to the drill pump end if needed to filter fuel or fluid i am pumping from A to B.
 

chucky

Active member
221
145
43
Location
TN.
Yes. Its a transmission cooler. or heat exchanger being that it is not an air to air cooler.

5 ton FMTVs have the air to air cooler to supplement the heat exchanger to the engine coolant doesn't have to work so hard to keep the coolant temp in check. If it was a 5 ton truck you could simply hook in on the air to air unit to flush everything

If you can chase the hose route easy enough the lowest line on the transmission is always the pressure out line with the top line being the return

Or if you can't chase hoses. Then remove both at the exhanger and place in a bucket. Start the truck for a second and shut down and see which bucket has fluid vs none.

I always flush then change the filter in the pan. Drain the pan of the fresh fluid and Filter what was drained from the pan thru a t-shirt or other small media. Or thru a supplement spin on system.

I have filter housing with a hose I can attach to the drill pump end if needed to filter fuel or fluid i am pumping from A to B.
That make more sence to me ! when i would flush a ford car i would just break the line at the radiator with it running and be pouring fluid in as it would pump the old sludge into a bucket we never had a machine i never tried it on a chevy but the same princeable .Ive got a source for all the transyn used i was thinking of just pumping it thru a 10 micron filter and use it and save 600 bucks thanks for the knowledge soon as i get to memphis im going to come by and check your place out hopefully soon Thanks again
 
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