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Discussion Starter · #1 · (Edited)
Hello,

This forum has been very helpful in providing all the details to add a tranny cooler so I thought I would post back some feedback.

First of all, many thanks to all who answered my many questions, in particular Bill and Gabriel.

I've been having problems w/ the temp on my tranny when towing a 7500lbs trailer. It went to 225-230 at times towing and it was as high as 180-190 in town in day-to-day driving.

The first thing I did was to install a PML pan w/ 9 qts of AMSOIL.
I cannot honestly say that this very expensive mod made a significant difference in the overall temp of the transmission. Lesson learn: try the cheap solution first (cooler).

Next, I purchase a Hayden 679? and ran it in series with the other coolers. That made a difference in town. I have not tried to tow w/ the cooler yet. In 90 degree weather, my highest temp after 1 hr driving stop and go in town was 150 degrees. Tranny Temps in the morning (75 degrees) were 125-130 in 15 miles or so stop and go driving to work. So, I can cautiously say that the Hayden is making a difference.

My next step is to bypass the radiator and I am planning to do that tonight. I think that the in-town 150 temp may be due to the radiator. I am happy w/ 150, however, it gets really hot here in Arizona during the summer so I want max cooling to climb the mountains comfortably.

The tranny needled at the end of today's drive ended up where it usually sat before the cooler and PML additions, however the actual tranny temp as measured by BDGT was 25-30 degrees cooler. I am not sure if there is any relationship with the radiator temp, but that temp went down a little too (5 degree), not much and it may be insignificant and not related.

One other thing I noticed is that it takes longer to cool the tranny fluid off once it heats up and after I shift the tranny down to 3rd gear to get more fluid flowing. This may have to do w/ more fluid being hot due to the PML extra capacity. I am not sure.

I will post temp results tomorrow and after I tow the trailer up the hills. I am cautiously optimistic that the cooler is going to deal with it effectively.

Mike
 

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Discussion Starter · #2 ·
Bypassed done.
Test drove approx. 13 miles ($3.89)
It looks like the bypass is good for 7-10 degrees according to BDGT.
We'll see what it does tomorrow in my way to work.


Mike
 

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This whole time I thought I was going to have to install a second external cooler to get the bypass to safely work.. This might change my whole perception, let's see what tomorrow looks like!
 

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Discussion Starter · #4 ·
Why are you concerned that the bypass would not be safe?

I thought the radiator pass through was there only to warm thing up. It rans at 195 degrees so it isn't of much use in cooling after a few minutes. Does the pass through have any other function? In other words, do I have to line up a tow truck for tomorrow ;-) ?

Mike
 

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Discussion Starter · #5 ·
Here is what this morning's stop and go drive brought.
16 miles, 30 min or so driving, 72 degrees outside

Start, tranny temp, water temp
7:22am, 66, 70
7:30am, 80, 156

Left the house
7:33am 100, 192
8:00am 145, 194

My conclusion is that for at least in-town driving, bypassing the radiator may not be worth the trouble even though it took less than 10min to do the bypass.
It is probably a good idea to consider the bypass in case the radiator ever fails but for cooling purposes, the bypass doesn't seem to change overall temps that much in town.
Also, starting tranny temps after 10 min warming up the engine (too long) may be too low in cold weather.

I am going to leave the bypass on for now to see how the truck does when I tow.
Overall, the tranny is riding cooler now.

Mike
 
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