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  #1  
Old 05-02-2014, 01:47 AM
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Myth or Fact: tranny cooler inlet/outlet down

I have a pair of plate & fin transmission coolers that the previous owner mounted as shown below, with the inlet and outlet facing down. Myth or fact: air will trap in the top of these and never bleed out, reducing how effectively they cool.

I am remounting these and would like to keep them in this orientation for ease of mounting and tube routing, but not sure if I need to worry about trapped air.

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Last edited by TheBandit; 05-02-2014 at 02:03 AM.
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Old 05-02-2014, 08:51 AM
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Since the pressure of the trans should be able to force the air out I say you are OK. Never have I heard of bleeding trans cooler lines.
But, however you go, I would get rid of the tight bends and make them larger radius bends for better flow. Elbows ie tight 90 bends are a huge flow loss in piping.
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Old 05-02-2014, 11:30 AM
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The old lines were 5/16. I am doing 3/8 throughout this time. The hand bender I have for 3/8 is a 15/16 radius.
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Old 05-02-2014, 12:41 PM
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Originally Posted by TheBandit View Post
SNIP< is a 15/16 radius.
That is approaching a 90 fitting at that radius, I try for a 4" Rad. or larger when ever possible. That and I have a hell-of-a-time bending thin-wall lines like 3/8" in to a radius much smaller then about 2", like the jitterbug it plum eludes me

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Old 05-02-2014, 01:39 PM
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This is the type of bender I have and it's physically very easy to put a bend into 3/8" steel line. I have never put much thought into the pressure loss through this type of bend because I assumed I was dealing with reasonably high pressures where the loss of a psi or two isn't going to hurt, but after looking into things a bit more it seems typical pressures from TH400 to the cooler are rather low; in the 5-25psi range at 4-8gpm. I would think the cooler itself would have a more significant pressure drop than the tube bends, but maybe not given all the fins/flow paths.

Thinking through this I'm starting to question running these in series vs. in parallel. Most of the larger coolers of this design have the same width (~11"), but with longer end tubes and more plates stacked, so putting these in parallel would make them function like the larger coolers. The pressure drop would be lower, but other than that I haven't thought through the heat transfer aspects.

The transmission didn't melt into a puddle with the old setup, but I have never had a temp gauge on it so who knows if I have been slow-roasting it from day 1.

Do you know if the TH400 output to the cooler is flow controlled (i.e. fixed displacement) or pressure based? In other words, does the pressure drop make a significant difference in how much fluid makes it through?
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Old 05-02-2014, 02:25 PM
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As for mounting, that is how the factory mounts them on late model GM trucks that had your engine/trans combo.

I mounted mine the same way and never had an issue with my 4l60e...
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Old 05-02-2014, 02:47 PM
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I've never worried about pressure drop (maybe I should) and always concentrated on flow. Reasoning being I want as much flow through the cooler as I can get, to expose more fluid to the cooler.

I may be completely wrong in this but that is what I do

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Old 05-02-2014, 02:59 PM
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That's why I ask how the flow is controlled. If it is fixed displacement from the transmission, pressure drop is almost inconsequential since the pressure will simply increase to maintain flow rate. However if the flow rate drops with pressure increase, then it becomes a flow issue which becomes a heat transfer issue.

I am assuming power required to pump this and heating of the fluid due to pressure drop are inconsequential.
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Old 05-02-2014, 03:45 PM
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Quote:
Originally Posted by TheBandit View Post
That's why I ask how the flow is controlled. If it is fixed displacement from the transmission, pressure drop is almost inconsequential since the pressure will simply increase to maintain flow rate. However if the flow rate drops with pressure increase, then it becomes a flow issue which becomes a heat transfer issue.

I am assuming power required to pump this and heating of the fluid due to pressure drop are inconsequential.
Pressure will be dependent on where it is tapped in to the system...
Talking out me arss I think it is tapped off the pump and thus it will be full system pressure what ever that is regulated to. However, as this flow has to do zero work other then get through the various cooling path restrictions (bends, fittings, cooler) the numbers you propose above would be adequate. My approach is that pressure does not infer flow thus the freer I get the flow in the mechanical design the happier I am... I don't know if I am right but I think I am.
As to your original question. I've mounted coolers in every angle and never noticed an issue, and I can not see how air could be trapped in the cooler and have flow at the same time...

Likely not much help

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Old 05-02-2014, 04:11 PM
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Per this chart the transmission line pressure is around 55psi minimum, but I have no idea where or how this is regulated. I think it is not the same pressure as what goes to the coolers because the pump has some kind of bypass valve to direct flow to the cooler.



There seems to be plenty of reading on this subject, so I will look around before I get too deep into this. I know more radius is better, but I'm not going to get too hung up on it unless it's causing a problem. I can't be too far off base as many have installed coolers in ways similar to this.
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Last edited by TheBandit; 05-02-2014 at 04:15 PM.
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Old 05-02-2014, 04:16 PM
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Quote:
Originally Posted by aggie91 View Post
As for mounting, that is how the factory mounts them on late model GM trucks that had your engine/trans combo.

I mounted mine the same way and never had an issue with my 4l60e...
Thank you for pointing that out! I found something interesting researching this. It looks like the gas application has the ports down while the diesel application has the ports up:

Here is a diagram showing the auxiliary cooler for gas applications - ports at the buttom straight out.



Here is the same diagram for the same model year truck for diesel applications. Ports at the top with a sharp 90 degree inlet.

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Last edited by TheBandit; 05-02-2014 at 04:46 PM.
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  #12  
Old 05-02-2014, 05:29 PM
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PCS does not recommend ports down: http://www.pscmotorsports.com/pdf/te...r_mounting.pdf
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Old 05-02-2014, 11:28 PM
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I'd say contact Art Carr transmissions. Maybe they have a Tech line you can get good info from. Some vendors have great tech support. Worth a try for future Q's.
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Old 05-03-2014, 03:06 PM
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I've always mounted the cooler so that the inlet is on the bottom and the outlet is on the top. This way there is no chance of having any problem with trapping air. The force of the fluid coming in the bottom pushes all the air out the top. This is one reason most all factory coolers are installed this way.

Also after having over 35 years in the pipefitting industry we always installed coolers/heat exchangers with the inlet on the bottom and the outlet on top. Installed this way also helps with how well the heat exchanger does its intended job.

My motorhome has 2 large coolers (20,000 lb. GVW size), which were installed by the last owner and they are mounted facing eachother. The fluid comes in the bottom on the first cooler and out the top, then goes in the bottom of the second cooler and out the top, back to the transmission. I also have a temperature gauge to watch how the temperature is doing and I've never had any problems with any overheating, even pulling long grades while towing heavy trailers. The temperature will go up some, which is to be expected, but not enough to cause concern.

Hope this info helps.
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Old 05-03-2014, 04:24 PM
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As a side note there is a HUGE dynamic difference between a Power-steering system and an AT.

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Old 05-03-2014, 07:25 PM
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Okay how does this look? One for the transmission (in line with the radiator's internal trans cooler) and one for steering.





This way I can do bottom in, top out for both and not worry about air getting trapped. They are mounted to the bottom of the condenser and I would add the through-fin zip-tie things to mount the top. I don't like how much the side brackets block. Maybe I could cut them down with the bandsaw?
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Old 05-03-2014, 07:49 PM
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Have you ever noticed that none of the factory's ever mount their Radiators, Heater coils, Air-Con condenser, or oil coolers, with those zip tie things that push through the fins and between the tubes... In-fact they often go to great lengths to isolate these devices or the bolt them in with what looks like huge overkill brackets.

Do you really need a PS Cooler on a street car? <Serious

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Old 05-03-2014, 08:58 PM
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The best automatic transmission coolers are manual transmissions that way the automatic can just sit on the garage floor where it stays nice and cool.

HAHA!!

Jaysin

P.S. I always try to mount any heat exchanger so that there is no possible way that there can be trapped air. In your case of trans coolers though I would think that even if you lost a wee bit of cooling from trapped air you have more then enough heat exchanger area for an automatic in a light weight car. The only time I have seen a big problem with an overheating auto in a light car is with a really high stall torque converter (5000+ stall). But then I don't do much with automatics.
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Old 05-03-2014, 10:56 PM
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Point taken on the zip tie things. They are hokey. I'll think about what it would take to mount them more robustly, but does the general location seem okay?

I plan to autocross some and thought for that reason I may as well run the second unit as a ps cooler. It's easy to plumb. Do you think I shouldn't?

Jaysin - I like your idea the best. This auto sucks but it's "free".
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Old 05-04-2014, 12:49 PM
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Point taken on the zip tie things. They are hokey. I'll think about what it would take to mount them more robustly, but does the general location seem okay?

I plan to autocross some and thought for that reason I may as well run the second unit as a ps cooler. It's easy to plumb. Do you think I shouldn't?

Jaysin - I like your idea the best. This auto sucks but it's "free".
The hardest thing to build is something that has 'Race Car' performance expectations that will be driven on the street. You have already compromised the priority of engine cooling with the silly AC system thus allowing me to easily say; of course that is a good location! I also understand that there is only so much real estate on the core support to hang Coolers off of but I would try to get the AT cooler into its own air stream if I could; even if I had to duct that air in through the bumper and dump it under the chassis after the splitter.
Have you ever had an issue with the PS heating? Like trying to parallel park in a spot that is 'just' big enough? Parallel parking is about as brutal as it gets on the street. I've never had a healthy Saginaw PS system in a car over heat, road or track. I will admit that I have installed PS coolers in endurance road race cars just to be safe but they were (guessing) 1/4 the size of what I see in your pictures or just a simple length of tube rolled to fit around the outlet edge of the fan shroud. In 4x4's with much larger tires yes I do like to run a good size cooler but even there I only run a single "U" shape cooler and the fittings are 1/2" in/out. PS can be a persnickety system and the most functional systems I've seen are the GM/Saginaw factory design.
In the end only you know that you need

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