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Discussion Starter · #1 ·
i'm installing an external transmission cooler so i need to know which line is out, and which line is return. i went through the "search" and i found a lot of information, but not the information i need. Dae has a great write up for his cooler, but that didn't help me either. he shows the in and out lines from the radiators point of view, and on a rodeo. here is what i want to know. from the transmission, not the radiator, which line is which? according to myisuzuparts.com., the longer line is the inlet (return), but on the 4 cylinder aishin transmission, the longer line is the outlet. the repair manual i have (factory) shows the 2 lines together and calls them cooler lines.
my engine is not running yet so i can't tell by touching the lines for temperature. your help is appreciated. remember, this is for the 2.8V6 4L30E transmission.

cheers, john
 

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He wants to know which line is which on the transmission itself. And since I dont have a Trooper, I would hate to give out the wrong information.
 

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Discussion Starter · #5 ·
OK. let me start over. i had everything out of my trooper. engine, tranny, complete front end, radiator, everything. i don't have any reference point on which line is the out line for the transmission. if i was just hooking it back up to the original radiator cooler then it would be no problem. but i've installed an external cooler and i'm installing a MAGNEFINE filter as well. so what i need to know is, which is the out line on the transmission for the filter flow?
Dae, if you read this again, you would be able to tell me. you have a 4L30E transmission. which line is hooked up to your system as the out line? the longer transmission tube or the shorter transmission tube?

cheers, john
 

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Discussion Starter · #6 ·
5 th rodeo said:
i am pretty sure on the 4l30e , if the rad is still connected to the tranny , the passenger side of the rad is the return to the tranny.
you're "pretty sure" or you're 100% sure. i need to know for flow reasons.
john
 

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Call a dealership that still services Isuzu's....there are still quite a few of them.

I too have the 4L30, I'd hate to tell you wrong though....my truck is covered and sleeping tight inside it's car cover, otherwise I'd go out and look for you....but I just took a shower and don't feel like lying in the dirt...did that enough today mowing.
 

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govno90 said:
5 th rodeo said:
i am pretty sure on the 4l30e , if the rad is still connected to the tranny , the passenger side of the rad is the return to the tranny.
you're "pretty sure" or you're 100% sure. i need to know for flow reasons.
john
i do know for sure the transmission line on the passenger side of the radiator is the return to the transmission ( on 2nd gen ) , what got me was the year of the isuzu , my rodeos that had the 4l30e were all 2nd generation. so i couldn't say for sure.

on 2nd gen rodeos with 4l30e or aisin auto's it goes tranny to drivers side, passenger side ( cooled fluid ) to transmission.
 

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Passenger side is return to tranny, I have my cooler installed in line with the trans output to the rad and it's on the driver's side.
 

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govno90 said:
Dae, if you read this again, you would be able to tell me. you have a 4L30E transmission. which line is hooked up to your system as the out line? the longer transmission tube or the shorter transmission tube?

cheers, john
I'll be able to check tomorrow morning, and i'll let you know if you still need it from the trans itself.
 

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The longer metal line that runs from the back of the trans, then runs above the other metal line is the output line.
The shorter metal line that starts closer to the bell housing is the return. Hope that helps.
 

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Discussion Starter · #12 ·
Dae said:
The longer metal line that runs from the back of the trans, then runs above the other metal line is the output line.
The shorter metal line that starts closer to the bell housing is the return. Hope that helps.
Dae thanks for looking into this for me. i'm glad that you were able to check the transmission line BUT, i'm still getting confused by Mediamonkey and 5th rodeo. they are both saying that the passenger side tube on the radiator is the return line and the drivers side tube is the outline. do the hoses that connect the transmission tubes to the radiator tubes cross over on rodeos? meaning does the longer outside tube on the transmission connect to the drivers side tube on the radiator. and, does the shorter inboard tube connect to the passengerside tube of the radiator? if they do cross over on your rodeos, then i have found the solution. if they don't crossover, then i'm still being told two different things.

thanks guys. i'm sure we'll get to the bottom of this dilemma.
cheers, john
 

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They may cross over, I juss lettin' ya know how it was on my twuck :)

I think Dae has a really good write-up on a cooler install, and it looked identical to what I have... Maybe I'm remembering wrong., darnit, now I've got to look later tonight lol!
 

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Hope this clears things up. I got this pic from my FSM, and it looks like the lines DO cross over somewhat. (the longer line is above the short one).

So I guess thats where all the confusion is coming from. Im right with your question about the lines at the trans itself.
And Mediamonkey11 & 5 th rodeo are right that the passenger side hose on the radiator is the return.

FSM pic


Showing how I routerd my cooler "after" the radiator. By leaving the trans output line alone. (I have since re-routed the cooler to "before" the rad)


Return line on the radiator side.
 

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Discussion Starter · #15 ·
Dae, Mediamonkey, 5th Rodeo. thanks for all your input. this is what i'm understanding from you guys so far. according to Dae's write-up photos, and also what Mediamonkey and 5th Rodeo have been saying is that on your vehicles (all rodeos) the return line is on the passenger side of the radiator. in Dae's write up, he shows a photo of the hoses with color coding. in the actual write-up he states that the hose with the green markings is the "output" line. that hose is attached to the upper tube on the transmission. the upper tube is the longer tube and goes to the rear of the transmission. so far, i'm understanding this part.
let's go to myisuzuparts.com. it says that the longer tube on the 4L30E is the return line. now i have 3 guys that say longer tube "output", one parts catalogue that says longer tube "return".
yesterday morning i went to a transmission shop and asked them what they thought. the guys looked in a repair manual and it showed long tube "return" line. 3 guys say long tube "output", 1 catalogue and 1 repair manual say "return".
again yesterday; on the way home, (i ride my bicycle to and from work) i went to another transmission shop. lucky me!! at the shop were 2 late 90's troopers. well actually 1 trooper and 1 acura. i asked the guys there my question. the guy working on the acura said (in spanish) the longer tube is the "return".
this morning i called what used to be the nearest trooper dealership. the guy in the service department answers the phone and i say "good morning sir. my name is john and i have a little problem maybe you can help me with. i own a trooper and...." the guy cuts me off and says "sell it". i gave him a questioning "what?'" he tells me that they no longer service isuzus. they still sell parts (for now) but that none of the ex dealerships in the los angeles does service. i thank him for his explanation and left it at that.
where does this leave me now? i have three guys are really trying to help me. they all say, i think, that the longer tube is the "output" line. i have two books and one mechanic that was working on a 4L30E that say the longer tube is the "return" line.
so, as you know, the reason i want to know which way the flow is going is not so much for the tranny cooler, but rather for the inline filter that i plan on putting on. the filter flows in one direction. i was still confused until right before quitting time. i was discussing my dilemma with Bruce. he's a gardener at the place where i work. well, he gets paid to be a gardener. but he's really a frustrated mad-scientist. (he own a spaceship) Bruce tells me that why don't i just put everything together without the filter. then take off one of the hoses from one of the transmission tubes and have someone start the motor for a few seconds. do the same thing with only the other hose off. this way you'll see which tube is blowing tranny fluid out. does this sound feasible to you guys?? i know you three have been trying to help and you're not giving me "wrong" answers, but none of us wants to do things over, right?

thanks again guys

cheers, john
 

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Very strange... Id check with JLEMOND and see what he has to say. I trust him 100%. As far as I know the passenger side of the rad is the return.
 

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the return to the tranny is the passenger side of the radiator , i have checked this many times , i also have put a " long trucool " tranny cooler and a magnefine filter on 6 rodeos , you are correct the magnafine is directional.
 

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Discussion Starter · #18 ·
5th Rodeo. let's play a game. let's pretend your rodeo does not have a radiator. now, in this game you have to look underneath your vehicle and figure out which one of the tubes on your transmission is the "outline" and which one is the "return" line. this game also consists of rules just like on JEOPARDY. your answer cannot be answered like this; "the passenger side tube is the return line" the answer has to state whether the long tube or the short tube is _________(fill in the blank).
you say that you have checked this when putting on filters, so i will trust what you say. but your previous answers to me have always used the radiator as a reference. i have a trooper. you have a rodeo. the radiators are different. in Dae's photo, i can't determine which side is passenger side. on my trooper, the bottom radiator hose is on the very corner of the driver's side. so please, someone confirm the transmission lines. whoever does this for me will receive 3 hug emoticons and 2 winky emoticons.
again, thank you for your help guys. (sorry if i'm being a pain in the a**)

cheers, john
 

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Discussion Starter · #19 ·
Mediamonkey
why was i under the impression that you have a rodeo? i now see that you have troopers. but still the radiators are different.

cheers, john
 

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govno90 said:
5th Rodeo. let's play a game. let's pretend your rodeo does not have a radiator. now, in this game you have to look underneath your vehicle and figure out which one of the tubes on your transmission is the "outline" and which one is the "return" line. this game also consists of rules just like on JEOPARDY. your answer cannot be answered like this; "the passenger side tube is the return line" the answer has to state whether the long tube or the short tube is _________(fill in the blank).
you say that you have checked this when putting on filters, so i will trust what you say. but your previous answers to me have always used the radiator as a reference. i have a trooper. you have a rodeo. the radiators are different. in Dae's photo, i can't determine which side is passenger side. on my trooper, the bottom radiator hose is on the very corner of the driver's side. so please, someone confirm the transmission lines. whoever does this for me will receive 3 hug emoticons and 2 winky emoticons.
again, thank you for your help guys. (sorry if i'm being a pain in the a**)

cheers, john
wow..

So many replies.. so few answers

John, I am in the same boat you are/were in.. I have a trooper (2001) and the rad is removed, and worse yet the long and short metal tubes are removed. They rusted away years ago and I replaced the full length with hose.. But I digress..

A little history
Two years ago the mech in my town told me I needed a new tranny.. Well after nursing it along for two years it finally started to go.. So I bought a new rebuild tranny from 'Transmission Authority' via Rock Auto.. So as noted above, at this moment, no rad installed, no long or short metal tubes.

My Plan
Install the new tranny, install the new rad, install an inline cooler (with fan).. Now I want the cooler to reside on the return from the rad.. The idea being if the rad does not cool off the fluid enough, the inline cooler will.. Granted, on cold days the fluid maybe a little colder than it should be, but, AFAIK the real problem with the 4L30L is burning fluid, so, I will just have to live with the fluid maybe being a little colder than it should be.

What I need to know
To do 'my plan' I need to know, like John, RELATIVE TO THE TRANNY, which is the OUTPUT and which is the RETURN.. Where the flow will be as follows

tranny out --> rad in --> rad out --> cooler in --> cooler out --> tranny in

Or using the tranny lingo,

tranny out --> rad in --> rad return --> cooler in --> cooler return --> tranny return

Now, if you don't know.. but feel you need to comment on this, please just PM me and spare this thread any more good intentions but useless info posts.

One more question
With regards to the rad cooler.. Does it mater? I mean if you swap the hoses your still going to get fluid flow and thus cooling.. Put another way, there is no check valve or direction flow check in the rad.. Right? Reason I ask is that is the impression I am under, but I see so many people making references to the 'passenger side' tube being the return line and cross over this and that.
 
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