Moving my Transmission cooler

ramdough

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So, I need to relocate my transmission cooler. I am looking at putting it right behind my rear axle (where my frame has been extended). This will mean longer hoses.

I have a few questions:

Once I disconnect the line, I assume a bunch of oil will drain out. I can put a bucket to catch the oil. Once I put on the new longer hoses…. Is there any issue when the slug of air gets pushed back to the tranny? Do I need prefill the cooler and hoses?

What pressure rating and temperature are the hoses?

Thanks!


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simp5782

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Hoses are 2500psi hydraulic. Hydraulic hose is generally rated for 260+ degrees.

You don't need to prefill hoses there are no air bubble issues on non pressure system
 

ramdough

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Hoses are 2500psi hydraulic. Hydraulic hose is generally rated for 260+ degrees.

You don't need to prefill hoses there are no air bubble issues on non pressure system
Thanks Wes!

Do you happen to know the size of those hoses off the top of your head? I am looking at upsizing them a little since I am going almost twice as far back. I need to see if my local hydraulic shop can go larger on that size JIC fitting.


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simp5782

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Thanks Wes!

Do you happen to know the size of those hoses off the top of your head? I am looking at upsizing them a little since I am going almost twice as far back. I need to see if my local hydraulic shop can go larger on that size JIC fitting.


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The cooler won't have fittings bigger than 3/4" if they are even that big so the hoses being that is all that would matter. No sense is going bigger hoses when the hole is only so big what it's going thru. You really don't even need that cooler. The heat exchanger will do its job.
 

Awesomeness

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The cooler won't have fittings bigger than 3/4" if they are even that big so the hoses being that is all that would matter. No sense is going bigger hoses when the hole is only so big what it's going thru. You really don't even need that cooler. The heat exchanger will do its job.
I agree that the truck would probably do ok without the cooler. It's fun to keep the original overkill capabilities of these trucks, though.

There is actually science behind upsizing hoses, even if the fittings are the same. (Yes, it matters... drastically sometimes.) Similar to the resistance of an electrical wire, there is a pressure drop across a length of hose. The longer the hose, the greater the pressure drop, and thus flow rate drop. By switching to a larger hose it drops less pressure per foot, so you can overcome the pressure/flow drop of the added length.

This is also why almost all the stock fluid lines on these military trucks have a custom oversized line on a fitting one size down (e.g. 1" JIC fitting with a 1-1/8" line and the fitting is also drilled out to a larger aperture than a standard 1" JIC has). So ideally you'll upsize the fitting hole too.
 

simp5782

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You would actually benefit more by using a diverter valve to run the transmission fluid away from the heat exchanger in the summer time and only letting the air to air cool it. Take some stress off the motor. And then open the plumbing for winter time to use both etc.

You would notice a drastic change in the fan clutch cycles.
 

ramdough

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I agree that the truck would probably do ok without the cooler. It's fun to keep the original overkill capabilities of these trucks, though.

There is actually science behind upsizing hoses, even if the fittings are the same. (Yes, it matters... drastically sometimes.) Similar to the resistance of an electrical wire, there is a pressure drop across a length of hose. The longer the hose, the greater the pressure drop, and thus flow rate drop. By switching to a larger hose it drops less pressure per foot, so you can overcome the pressure/flow drop of the added length.

This is also why almost all the stock fluid lines on these military trucks have a custom oversized line on a fitting one size down (e.g. 1" JIC fitting with a 1-1/8" line and the fitting is also drilled out to a larger aperture than a standard 1" JIC has). So ideally you'll upsize the fitting hole too.
I doubt I would go through the trouble of drilling out a stock JIC fitting if the claim is that the cooler is not even required. I do want to get a larger hose if I can.

If anyone knew off hand the size of the fitting and hose, I could shop around and see what I can find. Does anyone know?

Once I pull my hoses, I am going to want them replaced pretty quick. I don’t like making my truck immovable.


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Awesomeness

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I doubt I would go through the trouble of drilling out a stock JIC fitting if the claim is that the cooler is not even required. I do want to get a larger hose if I can.

If anyone knew off hand the size of the fitting and hose, I could shop around and see what I can find. Does anyone know?

Once I pull my hoses, I am going to want them replaced pretty quick. I don’t like making my truck immovable.


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Drilling them out isn't hard. You could probably even do it by hand. When I've had custom hoses made for the LMTV, the shops just chucked it up in a lathe and drilled it out... seemed like it wasn't their first rodeo, even though most of the time they didn't notice the difference without me pointing it out.

Not sure if your cooler uses the same hoses as the exchanger on the LMTV, but if so the hose part numbers are in my parts spreadsheet in my signature. A Parker store can make them from those numbers. (The part number obviously references various parts of the hose, like -06 is one of the fittings, but I don't know the order of the sections of the part number, such as which is the first fitting, which is the hose, etc.)
 

B-Dog

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I JUST looked into all of this recently to replace my hoses. I haven't installed new hoses so I can't say the following with any authority but in the next couple weeks I'd hope to tell you exactly what to order - or at least what not to order.

Stock hoses (on my truck) are MIL 13444. Temp 300° and working pressure 300-375lbs (depending on the size).
The female fittings on the hoses are a -16 JIC 37°. The male fittings are a variation of the same with an o-ring on the nose, I'm told that's called a 'flare-o'. I'm guessing a flare-o fitting is going to be difficult to find, should you need to replace one of the male fittings but if that's the case, just change it to a standard JIC. [really this shouldn't be a problem]

Like Awesomeness mentioned, the hose to and from the cooler are upsized to 1 1/8". The line from the tranny to the exchanger is 1".
If you want to retain the oil sample port you can get a male to female JIC fitting with a port. I think the sampling ports are dumb but I want to add a tranny temp sensor since I'm ditching the cooler so I'll use one of these.

1624580558411.png

I think if I was going to make the already ridiculously long lines, even longer, I'd consider doing some hard tubing but I'm not sure how difficult that would be...
 

Ronmar

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I was thinking the same thing, mounted hard-lines with jumpers at either end as that is a long run back to the tail end of the frame. I am going to do the same thing with that sample port, fit a temp sensor:)

is this to accommodate a box/habitat? I have seen some install it right behind the transfer case between the frame rails…
 

Mullaney

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I was thinking the same thing, mounted hard-lines with jumpers at either end as that is a long run back to the tail end of the frame. I am going to do the same thing with that sample port, fit a temp sensor:)

is this to accommodate a box/habitat? I have seen some install it right behind the transfer case between the frame rails…
.
Seems too that a metal line would fade the heat more quickly than rubber hose.
With a metal line properly anchored to the frame, heat would radiate through that connection too.

The M1089 has steel lines that feed and return hydraulic fluid.
Those hard lines run almost half the length of the truck (rubber hose JIC fittings on each end).
 

ramdough

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Drilling them out isn't hard. You could probably even do it by hand. When I've had custom hoses made for the LMTV, the shops just chucked it up in a lathe and drilled it out... seemed like it wasn't their first rodeo, even though most of the time they didn't notice the difference without me pointing it out.

Not sure if your cooler uses the same hoses as the exchanger on the LMTV, but if so the hose part numbers are in my parts spreadsheet in my signature. A Parker store can make them from those numbers. (The part number obviously references various parts of the hose, like -06 is one of the fittings, but I don't know the order of the sections of the part number, such as which is the first fitting, which is the hose, etc.)
Are the hoses you listed just for the water-oil cooler or the rear cooler?
Thanks!
 

ramdough

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I was thinking the same thing, mounted hard-lines with jumpers at either end as that is a long run back to the tail end of the frame. I am going to do the same thing with that sample port, fit a temp sensor:)

is this to accommodate a box/habitat? I have seen some install it right behind the transfer case between the frame rails…
To answer your question.


Yes, this is for a box. I thought about shortening the lines and having it behind the transfer case, but my vertical space is very limited, so I am not sure I will get very good air flow.

I think I would have to fab the hard lines myself and that may get expensive. Soft lines would be ideal.

Is there a major concern of creating back-pressure if I have longer lines?

Also, what is the manifold looking thing right behind the transfer case? Some sort of thermostat body?

Thanks in advance!


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Ronmar

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To answer your question.


Yes, this is for a box. I thought about shortening the lines and having it behind the transfer case, but my vertical space is very limited, so I am not sure I will get very good air flow.

I think I would have to fab the hard lines myself and that may get expensive. Soft lines would be ideal.

Is there a major concern of creating back-pressure if I have longer lines?

Also, what is the manifold looking thing right behind the transfer case? Some sort of thermostat body?

Thanks in advance!


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There have been a few I have seen who found the room pretty close Behind the transfer case. The fans move all the air anyway, so you don’t really need much room.

I don’t think the back pressure created by longer lines will be terrible, but I think you will find long 1-1/8” hoses not so cheap either:)

I am not sure what manifold you are referring to as I am not intimately familiar with the aux cooler circuit. Got any pics? Where do the lines connect? A thermal diverter might make sense to keep the temps up in really cold conditions…
 

ramdough

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There have been a few I have seen who found the room pretty close Behind the transfer case. The fans move all the air anyway, so you don’t really need much room.

I don’t think the back pressure created by longer lines will be terrible, but I think you will find long 1-1/8” hoses not so cheap either:)

I am not sure what manifold you are referring to as I am not intimately familiar with the aux cooler circuit. Got any pics? Where do the lines connect? A thermal diverter might make sense to keep the temps up in really cold conditions…
it looks like one line goes from the water cooler and the other to the transmission.

this must be a temperature regulated bypass.
 

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ramdough

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Austin, Texas
I took the cooler free…. Man that thing does not look as heavy as it really is. I pictured it weighing like a car radiator. Not so.

8294D1C5-60DF-4076-ADBA-16005A28B100.jpeg
So far I drained about a gallon out of the hoses and radiator. Next step is to mount the cooler so I can measure for hoses.

One thing I noticed is the cotton jacket burnt off where the muffler is. I could read the text on the hose and thought I would share.

0741B254-13D9-4F39-B942-9B2697C79E23.jpeg
 

Third From Texas

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I picked up this big bastard last month. BAE contracted it and I don't know what it was out of, but I think I may stuff it in my frame. It's NOS and cost me $50 but the bungs for the lines are 1.25" so I'll have to step down a hair, heh. It's 36" x 20" x 9" (with a 3" core).


bae6b0a9-e8d6-4729-b7de-a072e5b968e3.jpg
 
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