My Hayden 678 Transmission cooler install on 06 V6

oxnard111 said:

I finally installed my hayden cooler after purchasing it like 4 months ago. The install was pretty straight forward.

1) Had to figure out which line going on the radiator was exit for the tranny fluid. Figured out it was the bottom line. Bottom line = exit from radiator.

2) Mocked up the cooler in front of all other coolers. I used one existing bolt that is in the lower left hand corner. On two other corners I had to drill small holes to add hardware to hold the cooler in place.



3) Mounted the two other corners. I didn't feel making a bracket to mount the fourth (upper right) corner was necessary.



4) Ran the lines. From exit of radiator (bottom) the line went into the top of the hayden cooler. From the bottom of the hayden cooler I connected to pre existing exit of the radiator using a 90 degree elbow. I used an extra length of hose to cover the sharp edges going through the hole in the body.


5) I started it up to make sure there were no leaks and then moved onto adding extra fluid to make up for the extra volume.

6) I just followed the refill and level check instructions found in the mechanic's manual. Was a pain in the butt, but got it done. Here is a link to the PDF. http://www.mediafire.com/?09pcelpmccj



While I was at it I painted my front emblem.

Click to expand...

I just purchased a 3900# travel trailer myself, had a brake controller installed and have towed it some on flat ground, truck seems to do well. But if for nothing else than peace of mind, I want to go ahead and install a tranny cooler.

I am a bit thrown off by your step 4..

From exit of radiator (bottom) the line went into the top of the hayden cooler. From the bottom of the hayden cooler I connected to pre existing exit of the radiator using a 90 degree elbow

So you went from the exit of the radiator (bottom) to the top of the cooler, then from the bottom of the cooler.. back to the exit on the radiator?. I dont follow..

it seems like the flow for the whole system should be: Tranny exit line --> radiator input(top) ---> radiator output (bottom) ---> hayden cooler input(top)---> hayen cooler output(bottom)----> tranny input line.

is that correct?

is there a diagram anywhere?

I installed a Hayden 678 cooler today and I found a couple of things that may make the install easier for others.

First with the mounting of the cooler. If you notice on the center piece that runs from the lower cross member to the hood latch, there is a pre-drilled hole (I assume to mount the OEM cooler) that is about half way up. This hole is tapped with the same thread as the hole at the bottom of the center piece, M6-1.0. When using the slotted hole on the bottom left of the cooler, this 2nd threaded hole lines up with the 4th hole from the bottom of the cooler. A couple of M6-1.0 bolts from the hardware store and you are good to go without having to drill a hole in the center piece.

The second part is about the connection of the hoses. First, as in the OP, you remove the OEM hose from the bottom of the radiator and then run a new hose from there to the top of the cooler. But for the return hose, oxnard used a 90 degree elbow to connect the outlet of the cooler to the hose that was removed in the first step. I found that it was much easier and cleaner to use a longer piece of hose and run it straight from the hayden cooler to the transmission hard line, found under the truck behind the skidplate (follow the rubber hose to find them). When you disconnect the existing return hose from the hard line, you can pull it out of the truck completely (the other end was disconnected in the first step). Now you can route the new hose the same way that the OEM ran (through the hose holder thing). I also removed the mesh hose protector from the OEM hose and slid it onto the new hose and re-taped it. This prevents wear from the two hoses rubbing each other or the big engine coolant hose. I feel like installing the second hose this way is much cleaner, simpler and reduces the number of connections to make.

I can shoot some pictures if you guys are interested.