Transmission lines ?

Quick question, obviously picture of the tranny with the two lines top and bottom on my 95 sport, does anyone know off of the top of their head which line is the in and which is the out to help the noob. Getting ready to install tranny filter and cooler but don't know how to determine which line is the in and which is the out, the one on top or bottom? Any help would be great.

I believe in is on top!

-Drew

The in or out is on the top? Cause I believe the filter goes in between the out line and the raidator correct?

Never installed a aux. tranny filter or cooler. I would say the line on top is in and the line on the bottom is out. The best way to check is to hook up a transmission flush machine and it will tell you.

-Drew

ExplorerSportNu said:

Cause I believe the filter goes in between the out line and the raidator correct?

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Yes you can install it this way. Mine's a little different but here's the flow:

Fluid leaves tranny thru the lower of the lines on the tranny. It then goes to the upper connection of the radiator. It leaves the radiator thru the lower connection and goes to the 'in' on the aux filter. It then leaves the aux filter at the 'out' and goes to the driver's side fitting of the aux cooler. It leaves the aux cooler from the passenger side fitting and back to the upper tranny line into the tranny.

Since I already had an aux cooler it was easier to install this way. The lines from the radiator to the cooler are rubber and easier to deal with. No need to cut the metal lines this way.

Lee

There seems to be two trains of thought with respect to installing aux. coolers and tranny filters.

I purchased the tranny filter kit from Summit and found a Gen. 1 aux. cooler in a junk yard. The filter kit instructions indicate that the filter should be installed in the RETURN line (after the fluid has gone thru both the radiator and aux. cooler.

As a former racer, I prefer to filter fluids BEFORE they travel thru anything like a radiator or cooler. Why? Filtering before those pieces of hardware prevents any foreign matter in the fluid from reaching (and possibly clogging) said hardware. As far as I'm concerned, the filter is there to keep foreign matter from traveling thru the system. Also, it's easier for the pump to push hot fluid thru filtering media (as opposed to pushing cool fluid).

I asked one of our resident tranny experts Brain (Brian) which line was which. He replied that the line from the tranny that runs to the top of the radiator is the 'hot' (supply) line and the line from the bottom of the radiator is the 'cool' (return) line. In his truck(s) the 'cool' line runs to the aux. cooler and then the line from the cooler ('cold') returns to the tranny.

So, most likely, my install system will be: tranny to filter, filter to cooler, cooler to radiator, radiator to tranny (I consider the cooler to be more efficient in heat dissipation than the radiator). Compared to Brian's truck, my install will be almost opposite from the factory install. You may want to consider a tranny temp gauge, too. They're not too expensive and you can include the temp sending bulb port in the filter base or buy a 'manifold' for the bulb from Auto Meter (Summit has these).

Hope this helps - Dave.

Alright actually both of you helped a lot thank you, Dave I agree with your theory on filtering the hot fluid. So I will most likely place my filter somewhere in between the the line out of the tranny to the top of the radiator therefore filtering the hot fluid - does that sound correct? Correct me if i'm wrong but is there any difference between placing the aux cooler I have before or after the radiator - thoughts on this. I do have the an autometer tranny temp gauge, trying to figure out where to install it in this setup, I think I want to pull the temp of the fluid after it has left the aux cooler and radiator so I know the actual temp of the fluid circulating through the tranny - and thoughts on this.

Thanks guys

I'm no expert but I'll chime in with my $.02.

If you want to filter the fluid hot put the aux filter on the line running from the tranny to the radiator. If you want to meter it at it's coolest point, hook up your tranny temp guage to the other line coming back into the tranny. (Most I have seen on this board have the tranny temp guage hooked up to the port on the aux filter.)

I'd be the last to give Ford engineers any credit but the stock set-up has the fluid going from the radiator to the aux cooler. You'd think that if more efficient cooling would be achieved sending it thru the aux cooler first and then to the radiator they would have built it this way. Dave has stated that aux cooler first maybe the better way. I don't know and I defer to the experts.

Now having stated all this I'm not really sure any of it makes that big of a difference. As mentioned in my earlier post my aux filter is placed between the radiator and aux cooler..not the hottest but not the coolest either. I look at the aux filter and cooler as good insurance for a not so good tranny. I originally did a pan drop and internal tranny filter change before I installed the aux filter. I cut open the first 3 aux filters that I changed out and did not find any residue that I could see with the naked eye. I change the aux filter every 3000 miles with my oil changes and my tranny fluid always looks new in color. I also have to add about 3/4 of a quart of new fluid when I change out the filter so this amount of new is constantly being cycled in every 3000 miles.

I know...it's not scientific and probably not much help but like I said...just my $.02.

Lee

Alright yeah that helped, so since i'm wanting to filter the hot fluid i'll stick my filter on the line going to the top of the radiator ? I think thats correct and for the coolest point for the temp gauge it is the line on the bottom of the two lines going into the tranny correct, I just don't want to screw this up, thats why i'm double checking Trannys aren't cheap as I have already once discovered. When you say most of the ppl on the board have the temp hooked up to the filter i'm assuming thats the port in the middle of the filter housing unit, any advantages of disadvatnages to this over where I want to install it?

Thanks Ryan

I don't think you quite got the flow yet. I have a 98 4dr with the 5R55e tranny but I have to believe the tranny fluid flows the same way on yours. As per my earlier post, the hot line on mine (going to the radiator to be cooled) is the lower of the 2 lines on the tranny. It attaches to the upper connection of the radiator.

The return line (after being cooled by the radiator...and/or aux cooler if you you have the stock set-up) attaches to the upper connection of the tranny.

If you're getting confused just trace the hot line back from the upper connection of the radiator to the tranny. The other tranny line would then be cooled fluid returning to the tranny.

I believe that there are a couple of models of the aux filter...one has a spot to install a fitting for connecting a tranny temp guage and the other doesn't. If you have the one with the fitting and you install it in the hot line and connect the temp guage to it then it will measure the temp of the tranny fluid at it's hottest point (as it leaves the the tranny on it's way to being cooled by the radiator/aux cooler). This is not what you said you wanted to do earlier. You said you wanted to filter the hot fluid with the aux filter and measure the temp of the cooler fluid after it leaves the radiator/aux cooler. If this is what you want then you'll have to fab or tap into the line which is returning the cooled fluid to the tranny for your temp guage.

Lee

Between the three of us, we're all pretty much saying the same thing, just in different terms.

I don't see any sense (no offense) in checking the temperature of cooled tranny fluid. You'll want to check the temp. of the fluid as it comes out of the tranny (this is your indicator for internal tranny temp.). So, place the temp. gauge sending bulb in the 'hot' line, as close to the tranny as possible. If that means using an empty port in the aux. filter base, fine. If you have the filter base located near the front of the truck, I'd buy a manifold (Auto Meter) and install it, on the 'hot' line, close to the tranny.

With respect to the orientation of the radiator/cooler plumbing, Lee, you have a good point; Ford plumbed it so that the tranny fluid goes to the radiator and then the cooler. Did they do this because it's more efficient or because it was easier for the auto workers to install? I'm going to guess the latter because we sure know that a lot of 4R55 and 5R55 trannies have failed due to overheating. Since it's all one big loop, it's probably 6-of-one and half-a-dozen of the other.

Based on my experiences, I'm going to stick with the flow layout I described. If someone decides to plumb it differently, I doubt there will be any adverse consequences.

$0.02 - D.

Bronco638 said:

With respect to the orientation of the radiator/cooler plumbing, Lee, you have a good point; Ford plumbed it so that the tranny fluid goes to the radiator and then the cooler. Did they do this because it's more efficient or because it was easier for the auto workers to install? I'm going to guess the latter because we sure know that a lot of 4R55 and 5R55 trannies have failed due to overheating. Since it's all one big loop, it's probably 6-of-one and half-a-dozen of the other.

$0.02 - D.

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Well said Dave...I was thinking the same thing about which way it was easier for Ford to install when I was typing my earlier post. Hope you didn't think I was discounting your theory of aux cooler first and radiator second...I was only mentioning the stock set-up and admitting I didn't know which would be better.

I did have one afterthought and maybe someone who knows how the radiator actually cools the tranny fluid can chime in. My thought was that if it's a staged cooling type of thing..ie: the radiator is only able to cool the fluid to a certain point and the aux cool is necessary to further cool the tranny fluid to an ever lower temp. Now once again I'm not discounting what you said but if that were the case, conceivably, you might actually be slightly raising the temp of the tranny fluid if you reverse the plumbing. You're probably correct that it's just one big loop and it doesn't matter but now you've made me curious. Inquiring minds want to know.

Lee

I've learned never to take offense to anything people post here. Although, in your case, I knew that you were simply stating what you knew to be true (actually, Lee, I find you to be a good source of info, based on your other posts). No offense taken.

Based on what I know of old Mustang radiators, the fluid simply dumps into a cavity in the radiator and the heat is carried away by a small amount of the cooling cores. As we know, it's not very efficient. However, if the Explorer radiator is different, I'd like to know, too. And, Lee, you might be right about "adding" heat to the fluid by circulating thru the radiator last.

Sounds like we need a test with several temp gauges and two different plumbing circuits......

Bronco638 said:

Based on what I know of old Mustang radiators, the fluid simply dumps into a cavity in the radiator and the heat is carried away by a small amount of the cooling cores. As we know, it's not very efficient. However, if the Explorer radiator is different, I'd like to know, too. And, Lee, you might be right about "adding" heat to the fluid by circulating thru the radiator last.

Click to expand...

Dave...I don't claim to know anything about the inner workings of the tranny fluid cooling part of the radiator so I'm looking at this as a learning experience.

Did those cooling cores on the Mustang have engine coolant running thru them?...ie; is there some sort of heat exchange between the engine coolant and the tranny fluid? If so, then the ability of the radiator to cool the tranny fluid may be dependent on the temp of the coolant. If this is the case then I could envision a scenario where an extremely overheated engine (ie; towing a big load up hill or something) could in fact raise the temp of the tranny fluid if you reverse the plumbing. Don't mean to beat this thing to death...still just curious how it all works.

Lee

If I recall, the Mustang has a top-to-bottom flow radiator, which is rather inefficient. The Explorer has a cross-flow radiator (more efficient) and is why the tranny lines attach to the driver's side of the radiator (as opposed to the bottom, like an old Mustang). Anyway, since the bottom of the radiator contained coolant, the tranny fluid circulated thru a finned tube within the bottom tank of the radiator, thus transferring heat (optimally, to the coolant not the other way around).

So, yes, it's possible to transfer heat from the coolant to the tranny fluid provided the coolant is hotter. (You know, the more we chat about this the more I may change my plumbing circuit). If you happen to have a good radiator shop near by, they would most likely be able to explain exactly how the transfer of heat occurs between the tranny lines and the coolant. I seriously doubt there's any real difference in radiator design between makes/models.

Thanks Dave.

Yeah, I think I'm gonna leave mine with stock set-up as is....although I have to admit, you did make me stop and think about this.

Lee

Lee S. said:

....although I have to admit, you did make me stop and think about this.........

Lee

Click to expand...

Yeah, me, too. Thanks for sharing your thoughts/ideas. I may end up having a conversation with my Professional Engineer bother-in-law about fluid dynamics and heat transfer. I have a contact at Ford but he programs robots on the Expedition assembly line and may not know anyone who can answer our question. If I get any good feedback, I'll post it.

Follow Up:

I spoke with my brother-in-law about fluid dynamics and heat transfer.
Short Story: Ford has it right with respect to the plumbing of the aux. cooler.

Long Story: We know that the current setup uses a fluid-to-fluid heat transfer (the tranny fluid circulates within a tube inside of the radiator side tank). Heat flows from greatest concentration to least concentration. So, provided the coolant is cooler than the tranny fluid, the tranny stays cool (relative to the fluid temp as it left the tranny). As an example, say the coolant is 200º and the tranny fluid is 250º. If the exchange was 100% efficient (which it's not), the tranny fluid would be able to dissipate 50º of temperature. If the opposite is true (hotter coolant than tranny fluid) then the heat from the coolant will dissipate into the tranny fluid). Since that could occur, it's better to route the the tranny fluid thru the aux. cooler last. The exchange of temperature between tranny fluid and air is not as efficient as fluid-to-fluid but it eliminates the possibility of "adding" heat to the fluid before it returns to the transmission. Returning to our example, if 50º of heat was dissipated into the radiator, then you might lose another 20º in the aux. cooler (200º tranny fluid, say 80º ambient air temp = 180º tranny fluid temp as it returns to the tranny). I still plan to install the filter in the "hot" line (as the fluid leaves the tranny) and will install the temperature gauge bulb in the filter base. But, the aux. cooler will be downstream of the radiator.

D.

Thanks guys, for a very enlightening discussion of heat transfer. If I may add a couple of thoughts that have already been touched upon:

As was noted, the trans cooler is located in the 'outlet' side of the radiator, because that's where the coolant is coolest, perhaps as low as 150* or less. (Assuming the coolant enters the radiator at a thermostat opening temp of 190*, an efficient radiator should cool it down about 40* or so.) We usually think of a radiator as being 'hot', but the driver's side outlet is relatively cool. Not really cool, but let's say less hot.... :fire:

Also, the ATF lines are made from steel for two reasons. One is obviously for durability, but the other is for added ATF cooling. After running through several feet of air-cooled steel tubing, both to and from the radiator, the ATF has to be cooled a considerable amount. Those spin-on ATF filters probably add a lot of cooling too. I've considered adding one and fabricating air ducting to it; that way it would filter and cool at the same time.....

ROE