From Faq
Hayden Model 678 Transmission Cooler Installation
Difficulty: 2/10. A 2 instead of a 1 because if it's windy you might get ATF blown on to your shirt :).
What you need to buy:
- The cooler. I used a Hayden 678 from Pepboys.
- Extra tube. I just bought the package of 4' from Hayden at Pepboys.
- ATF. You'll need at least a little bit to accomodate the extra volume you now have. Now is also a good time to do a drain and fill. So just buy two gallons and call it a day.
What you should already have and will need
- Pliers to undo those fancy hose clamps that toyota gives you.
- Phillips screwdriver for your new hose clamps.
- Bucket to catch fluid.
The first thing you'll want to do is pull the grill off of the truck. Pop the hood and look behind that fancy chrome grill. You'll see 4 or so tabs along the top and 3 or 4 on the bottom. The tabs disconnect by pressing down on the them, like a switch. So get all of the tabs undone and remove the grill.
Now you'll want to line up the tranny cooler. Even the "tiny" model 678 doesn't fit in there without some finaggling. I had to move that hardline that runs in front of the AC condenser up out of the way temporarily. It unsnaps on the right and there is a little screw holder on the left that can be undone. Then gently pull the line out of the way. Now test fit the cooler. Try not to bash the fins on the condenser too badly. When you've found a spot that looks good (mine is almost centered) pull it out and stick on the little foam pads. You'll also want to put the fancy cable tie in place now. Slide the cooler into place and secure it. It's a tight fit with those pads but it does fit. Wahoo.
Now get your new lines into place. My leftmost line goes through a hole in the front of the body. The rightmost line goes up and between the condenser and the radiator before going to the left and down to the existing tranny lines.
Now is a good time to put that hardline back into place if you moved it.
Now comes the part where you actually connect the thing. You need to make a decision here. You can either put the cooler before the stock cooler or after it. The TRD cooler (made by Hayden) instructions say to put the cooler after the stock cooler. This is what I did. The inlet to the radiator (relative to tranny) is on the passenger side and the outlet is on the drivers side. So I disconnected the drivers side one, fluid leaks out but not much, and then connected the new line from the cooler. Doesn't matter which one. Then I disconnected the other end at the hardline. My tube had kind of siezed on there, pulling on the hose did nothing but twisting helped break it free. Then I connected the other tube from the cooler to it. I double checked my connections and then started up the truck and ran it through the gears, doing a little powerbraking to run fluid around. Then I checked the level and added as appropriate.
Optionally you can now do a drain and fill. Put a bucket under the tranny and pull the plug. Let her drain til she drains no more. Put the plug back in and add a gallon. Start 'er up and run it around. The fluid level will probably still be a little low so add more. Maybe 1/2qt.
I still don't have a thermostat so I have no idea how hot this thing is running. But after driving if I go up and feel the cooler it is warm, so it must be doing something. Neato.
Extra comments from Hunter95 of TTORA:
Good write-up. Thanks.
I used it to install my cooler last night. I do have a couple of comments to add in case anyone else tries it (~2 hr job).
I have a 95 4x4 ext cab 4 banger. I installed the Hayden 679 cooler.
My additional comments to the write-up.
- You will have to remove the front skid plate.
- You have to loosen/remove the 2 bolts on each side that hold in the parking lights or you will not get the grill removed.
- Buy extra hose. You will need it (I used 8ft in total - 4 came with kit / purchased 4 extra). Get the 3/8 inch hose no matter what they try to sell you. I tried 5/16th as that is what they sold me and I could not get it on. (expletitive!!)
- The fluid return after being cooled out of the radiatior on my truck was on the passengers side. Make sure you check yours.
All in all not too bad of a project...The 679 fits but it is tight...If you are thining about doing this check ebay for a Hayden cooler. I picked mine up for about $20 bucks 2 weeks ago. Throw in the extra hose and a little fluid and the project cost me less than $30.
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