So I have a 22re 1st gen 4runner with an automatic tranny. I want to install a tranny fluid cooler but have some questions. 1st, which line is the fluid return line? The one on the drivers side, or passenger side of the radiator? Also what size cooler should I get? Is there such thing as too big of a cooler? Thanks for your help.

 

First, I dont have that engine anymore so I can say for sure.. I WANT to say the passneger side.
Second, installed correctly you dont need that big of a cooler. Just so you dont freak out and get some massive, had to install thing. You get some good airflow on that thing, even a small one is going to work WONDERS.

 

The one i'm looking at is 3/4"x7.5"x11"

 

Sounds like s good size. Seriously, unless your Tranny is overheating all the time(indicitive of a stuck clutch plate or something else really wrong, which a cooler wont fix) anything you pick is going to be good.

 

That cooler should be about the right size, it's the same as the one I have with my 3.4. As for the lines I have no idea on a 1st gen, but mine were colour coded, red for hot to the cooler and blue for the cool return. Of course with a 20 year old truck even if they were coloured in the beginning they might not be now.

 

if you want to find out which line is which... just pull one of them and have someone crank it over while you look at the line...if fluid comes out that hose, that is the delivery line, if it comes out of the rad...it is the return line

 

I want to say it's the passenger side. Those who have installed a cooler on any engine, which side was the return line on? I'm going to assume toyota didn't swap the sides for different engines.

 

So in doing some more research I found that the return line is not the same on all engines. Help.

 

The one that comes out of the front of the trans is the presure line. Just follow it.

 

Thanks. So im assuming that the rear line on the tranny is the return line.

 

What I see in the diagrams I have is that the passage 'out' of the transmission on the 'passenger' side (right side when sitting in the cab) is the return line.
On the other hand, you could completely bypass the radiator with the cooling system you have and not go wrong. That means that it doesn't matter which is which.

 

So the passenger side hose on the lower part of the radiator is the fluid return line? From what I read it's best to let the fluid go through the factory cooler, and then through the aftermarket cooler for the best results.

 

Sort of, I suppose...
that means that the radiator has cooled the trans fluid down to somewhere around 180 degrees fahrenheit (given the temperature of the radiator fluid) and your external cooler will cool the trans fluid even more.

 

Let me be the first to say that cold transmission fluid 'can' cause your transmission to make funky shifts.
So your transmission fluid needs to be at least X degrees warm. If you cool the fluid TOO much, your transmission will act like it's always cold and shift at weird times.

 

Well, in the past I've put them on some trucks and cars, and if the cooler doesn't specifically say to hook the IN up on one side and the OUT on the other, then it shouldn't matter either way.

All it's doing is run'n the fluid threw the vanes to cool it off; there's not any sort of one-way valve in there or anything; it's just a tiny radiator. If both the lines are the same diameter, it shouldn't make any difference at all.

If ur all that determined to find out which line is which, just get a buddy to sit in the truck, pull one line off, then tell him to start and then shut the truck off mediately. Take note of where the fluid shoots from; if it comes from the LINE you just pulled off, that would be the IN line; if it comes from the RADIATOR, then that would be the OUT line.

Of coarse that can be a bit of a mess, but it works, and so long as you don't go driving around with the lines unhooked, and can't cause any harm. But it works flawlessly for identifying the lines!

 

I'm leaning toward 'both' lines going to the cooler and no lines going to the radiator.

 

So according to Flash319 and this thread http://www.ultimateyota.com/index.ph...26&topic=678.0 the return line is the back line on the tranny, so i'm going to go by that. Thanks everyone for your help.

 

Don't do that.

Transmission fluid must be at operating temperature or you can shorten the life of your transmission and cause funky shifting. You already know that the truck doesn't shift properly when it's cold, it is sluggish and stuff. Don't make it any worse!

Ideally, the trans fluid cooler would run on the out hose, before the rad heat exchanger. Also, the fittings on the cooler should either be on the side or the top, never the bottom of the cooler. If they're on the side, run the fluid in from the bottom fitting. The top fitting should flow into the rad heat exchanger and then from there flow back to the transmission. If the fluid fittings are on the bottom, you'll have an air pocket in the cooler and you will reduce it's effective size. Which makes the whole exercise a waste of effort.

With the fluid flowing through the air-oil cooler first, if there's excess heat in the fluid, it will cool down. If it's too cool, the coolant in the rad will bring it up to operating temperature.

On some new cars like the new Land Cruiser or LX570 there is an oil thermostat to regulate the flow of the trans fluid. When it's cold, it only flows through the oil-water heat exchanger. When the fluid is HOT it flows through the air to oil cooler and bypasses the oil-water heat exchanger.

The small size 4x10 coolers work fine. Try to mount it in the airflow path of the fan, so that the fan will draw air through it, even when the truck is stopped or at crawling speeds.

If I were going to the trouble of mounting an aux cooler, I'd probably mount a spin-on filter kit somewhere too. Just remember that the oil must flow into the outside ring of the filter and out through the large middle hole. I'd also install a temp gauge just for fits and shiggles. Or I'd just route it before the oil-water heat exchanger and call it a day. And go wheeling for the rest of the afternoon.

 

Haha. Don't worry. I'm the one putting on a cooler, not him. Thanks for the info. and the comment about the fluid being to cold isn't really an issue for me. Its a wheeling only rig, so if I'm driving it, its going to be in 4wd crawling.

 

Ok, well if thats the case; im dubious of actual effect. Not that your going to hurt anything, but like the coolant in your engine; the fins on the cooler only work with air going through. Obviously, depending on where you install it the engine fan will help pull air through, but im not sure how 4low crawling is really going to get moving to really make it effective in terms of air moving across?

Just something to think about. Its one of those funny little things, the faster your car/truck is going, the better at cooling your radiator and tranny are.