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Transmission Cooler Install DIY Guide

Old 07-11-2012, 01:35 PM
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Thumbs up Transmission Cooler Install DIY Guide

Transmission Cooler Install

This was done on my 6th gen Accord with the F23a4 4cyl VTEC however this mod will work and be beneficial for the J30 V6, F22 and K24 accords as well. I am replacing a Tube and Fin cooler with a plate and fin cooler. If you want the ultimate in efficiency then find a "stacked plate cooler"

DO NOT WASTE YOUR MONEY ON A "TUBE AND FIN" COOLER. They are crap! and won't effectively cool your transmission.

You want to find a stacked plate cooler, it is designed like your radiator. They are at least 30% more efficient, I have found mine to be upwards of 50-60% better than the tube and fin cooler I had previously.

Keeping your transmission cool is the best way to prevent future failures. Here is a graphic showing what overheating can do.

Things you'll need:
Screw driver (or 1/4 inch socket)
Zip Ties
2.5' of Transmission Fluid Line
3 qts of transmission fluid
10 MM Socket for removal of the bumper
Plate and fin transmission cooler like this one

It is easiest to do this after the transmission has been drained but its unnecessary.

1st - Remove Front Bumper
- There are two 10mm screws at the upper corners in the wheel wells
- There are a handful of plastic plug fasteners on bottom (two on top part of the grill)
- Once these are all out start from one side and pull the bumper down and away from the front of the car.

2nd - Locate the transmission cooler lines (your car has a stock cooler, what we will do is run this cooler after the stock cooler). These lines are on the passenger side of the engine in-front of and below the distributor cap.
- There are two lines coming out of the transmission that you can see from under the hood, the black tube in this picture shows the fluid out line, the bronze tube is the return. Unless you add an inline temp sending unit you will not mess with the OUT. But the return will come from the new cooler rather than the stock cooler. Note: The feed and return lines for the J30 V6 are located in a different area. Just find the stock cooler (bottom of the radiator) and trace the lines back to the source.

follow the out tube to the stock cooler, we will not do anything to this line unless you want to instal a inline temp gauge using brass fittings

this picture (is on its side) but shows the hot line in to the stock cooler.

The Out line (from the stock cooler) is what we will be extending to the aftermarket cooler. The out line lives right next to the lower coolant line on the radiator. This picture shows the out line.

We will take a section of tube and connect it to the out hub on the stock cooler. Then run it around the front frame member to the front of the radiator. The best place for the cooler is in front of the radiators behind the bumper.

I installed a winter bypass valve so that in cold winter months I dont over cool my transmission. This is not necessary but can be beneficial if you live in a place like Colorado.

the feed line is on the bottom right. And the Return is the T fitting with the tube facing down. The other connectors are for the Cooler. Both valves are closed in this picture, I did this so that the fluid did not run out all over my shop floor. Make sure that you create VERY clear diagrams showing the summer and winter positions if you add this valve. I suggest keeping a copy of these in the glove-box in-case you sell the car and forget to communicate this important adjustment. Closing both will cause your transmission pump to burn up, burning fluid , burning clutches and hardening seals.... Don't let this happen to you, understand what position your valves are in.

Once you figure out where to hang the cooler (just use your imagination there are endless ways to configure it) then you need to hook it up. I opted to have the feed come in at the top so that it cools as it moves down the core.

Make sure that any bend that you have in the tube is 3" in diameter. Any tighter and you will start to stress the pump and cause flow issues.

Like I said earlier I did put an inline temp gauge on the out line to keep an eye on the temps leaving the trans. Here is a picture of that setup.


Last edited by Silver6gen; 12-11-2012 at 01:53 PM.
Old 07-14-2012, 01:22 AM
WheelBrokerAng's Avatar
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Location: Canton/Massillon, Ohio 44646
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Thumbs up Excellent Write Up In This Post

I'd like to Thank You for this good informational write-up here in the forum..
Thank You for taking the time to take the pictures and do it up as well as you did.

Click My Image below...
Attached Thumbnails Transmission Cooler Install  DIY Guide-later.gif  
Old 07-17-2012, 10:44 PM
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Thank you Wheelbrokerang,

Some other tidbits of information for everyone.

This is my second transmission and with the temp sensor reading the temp of the fluid coming out of the transmission these are the normal temps that I noticed on an average 75 degree Colorado day. Things will be different in different climates and temperatures.

Short Drive - 160*
10+ Miles through stop and go city not going above 40mph - 190*
Interstate Driving (flat) at 75mph for 30+ mins - 170-180*
Mountain Pass Hill climb lots of WOT (I-70) 60-70mph - 200-230*

If you have a trans temp gauge and see you temps hit 220+ start backing off and taker easy.

Here are a couple things that will cause higher than average trans temps.

1. Old fluid (does not transfer heat as well)
2. Trashed radiator (this is where the cooler will help)

I hope people find this useful as I believe it is an ESSENTIAL upgrade for any accord 1998-2002.

Some have even installed an inline filter, however I opted not to do this as once the filter starts loosing efficiency it will restrict flow and can cause the issues it is designed to prevent. Keep in mind though, there are overpressure bypass kits available if you would like to do this as well.

Last edited by Silver6gen; 07-17-2012 at 10:47 PM.
Old 11-20-2012, 10:38 PM
Join Date: Nov 2012
Posts: 5

I love your full detail. Im on my second transmission too I actually just bought the transmission cooler but needed to have it installed. Now I have your tutorial and pics! Thanks
Old 11-25-2012, 10:46 PM
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Glad you have benefited from this post. Please let me know if anything is unclear or inconclusive I will happily help you complete this mod.

Old 05-21-2015, 07:38 PM
Join Date: May 2015
Posts: 3

What are those valves called and where can I find them? Awesome write up thanks
Old 05-22-2015, 06:54 PM
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Those are brass valves that can be "had" from many places. IMHO if you are going to add a cooler, no need to have shut off valves.
Old 05-22-2015, 07:12 PM
Join Date: May 2015
Posts: 3

Would it be bad for my trans in the winter?
Old 05-23-2015, 05:48 AM
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You will be fine
Old 05-23-2015, 06:17 AM
Join Date: May 2015
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Thank you sir

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