Mounting a Davies Craig Transmission Cooler with KAON Brackets

[GeeWhizz Senior Member Find all posts View Profile Close GeeWhizz]

I've just ordered the KAON Transmission Cooler kit for my 1GD GX Prado. I like the idea of a mounting bracket kit rather than the plastic through-radiator mounts that Davies Craig supply.

However, the KAON brackets are stainless steel and the oil cooler mounting flanges appear to be aluminium. From my recent experience with a aluminium/stainless steel combination, when exposed to the weather, the aluminium corodes relatively quickly where it touches the stainles steel.

My question: does anyone know what sized bolts are supplied with the KAON kit? I'm thinking of ordering some nylon shoulder washers (also called "top-hat" washers) to keep the two different metals apart. (I know the KAON video refers to M6 bolts on the body ends of the mounting brackets).

[Prada Lurker Find all posts View Profile Close Prada]

Love the KAON gear! I've lived and cruised on a yacht for the last 6 years, and have plenty of dissimilar metals issues. I doubt that your Prado would be exposed to enough conductive electrolyte ie. salt water to cause a corrosion issue. But just in case, good seamanship would require you to apply a liberal coating of Tefgel or Duralac between the two metals. I'd go for the Duralac as it dries to bond the fasteners, just like Loctite.

Duralac Jointing Compound 115ml, $34.95 | Whitworths Marine

[GeeWhizz Senior Member Find all posts View Profile Close GeeWhizz]

I'm back from our first trip towing a 2 tonne Camper Trailer and very pleased with the result.

To answer my own question in post #1, the bolts supplied with the KAON / Davies Craig kit were M5. The mounting holes in the new radiator were just under 8mm, so I ended up buying a pack of 5mm x 5mm nylon shoulder washers and a pack of 8mm nylon flat washers. This keeps the aluminium radiator electrically isolated from the rest of the vehicle, minimising future corrosion due to salty roads and tracks in rural areas and the outback.

Mounting the transmission cooler radiator was the easy part, except that five of the thirteen plastic push-rivets that secure the cover between the grille and the radiator snapped or shattered during removal. I replaced them with Champion TF81 Scrivets from Repco. Rearranging the ATF plumbing to route the fluid from the existing radiator outlet to the new radiator and back to the transmission's return pipe without losing too much of the (old) ATF was quite a challenge. The rubbery plastic protection covers that come with the Davies Craig ("DC") radiator were invaluable for temporarily plugging the existing fittings while getting reading to connect the new hoses. Not an easy task, though - the space to get your hands in to fit the new hoses is very limited!

Once fitted and clamps tightened, the new configuration was leak-free after a test drive. I've now done 1,500km with the new radiator and ATF temperatures, as read from the CAN bus "OBDII" network, are between 15 and 20'C lower than before - typically below 80'C when towing the big trailer.

I've seen questions and discussion on which way the ATF should route through the two radiators. The vehicle's main radiator typically keeps the engine coolant in the range 80 to 90'C, although it can get up to 100'C under load in hot conditions. It makes sense that the ATF should route to the existing radiator coil FIRST because that radiator can't get the ATF cooler than the engine coolant temperature. ATF is best kept under 80'C for longest transmission life. Unfortunately, the transmission's (hot) outlet needs to go to the top connection of the main radiator. Then out of the lower connection (much harder to get to) via a new hose to the DC radiator and then back to the transmission's return pipe.

[watsea Member Find all posts View Profile Close watsea]

Just reviving an old thread.
I am considering adding a transmission cooler to my 2019 Prado with a 1GD motor.
Some comments previously are suggesting the transmission cooler should come after the motor radiator.
However, my thinking is that the transmission cooler should be fitted (in series) before the engine radiator.
My reasoning:
* Most times my engine coolant runs at 86 deg, rarely 85 deg, and when towing 86-88deg, and sometimes to 91deg while towing my van and on a hill.
* So if the transmission fluid was a similar temperature to the coolant, the transmission fluid would get pretty good longevity and also the transmission fluid would get to a suitable operating temperature via the engine radiator.
* If the transmission cooler is before the radiator, transmission fluid heat loss via the cooler would reduce heat going to the engine radiator.

I tow with the transmission in S4.

This YouTube https://www.youtube.com/watch?v=XvNZsXSn0QY shows fitting a transmission cooler with the cooler after the engine radiator. The particular cooler has automatically opening valve that bypasses the fluid from the cooling fins of the cooler until the fluid reaches its appropriate operating temperature. That is ok.

<<Edit:
The cooler in the particular YouTube has a valving system that causes the fins to start cooling at 82deg with full cooling at 96deg, rather than bypass.>>

The YouTube also shows the direction of transmission fluid flow in the system including the engine radiator. At 14:40 in the YouTube, it demonstrates that the transmission fluid exits the engine radiator from the top. This means the transmission fluid enters the engine radiator at its lower connection.

So, rather than fit a transmission cooler with an automatic valve, has anyone fitted a cooler in series so that the cooler is before the engine radiator?
If so, any real difficulty in doing the fitting of the transmission cooler and the plumbing required?

[whitewhale Lurker Find all posts View Profile Close whitewhale]

I've fitted mine in series as per Kaon instructions. Although I have the older Davis Craig cooler without the bypass.
Yes it drops the pan temp a good amount but the best part is the torque convertor temps don't spike up as quickly and cool off quicker too. I watch TC temp more than pan temp.
if you have the cash, get a TC lock up kit. The temps will stay low to the point the cooler wont be necessary. I haven't proved this on my car but has been confirmed by a friend with his hilux and by the tuner that i had flash tune my car.