1HDT/1HDFT (JDM spec) ATF cooler lines to radiator

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Glenn-BJ74

Glenn-BJ74

10 Year 15 Year
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I want to confirm that the hot side of the ATF cooler line (out from trans) enters on the right side of the bottom of radiator and returns back to the transmission out on the left side of the radiator (from the driver's perspective).

It is difficult to trace these cooler line on the A442F as they go over top the transmission and look like they cross a few times. On start up the ATF is heated up by the radiator, which makes it difficult to determine which one is which.

Thanks
 
I don't have it on me but it shows in the engine manual.

Or remove one of the cooler lines into the transmission cooler, disconnect the fuel solenoid , and crank her over and see
 
I'd love to confirm this as well, looking to install an OEM trans cooler and do a full fluid change in the near future.
 
I'm also planning to do this and have all the OEM parts. Only thing missing for me is how to plumb the OEM cooler. If any HDJ81 owners can confirm that the right side fitting of the radiator is the hot side, that will be great.
 
if you lay down under the front of the left of the truck you will see 2 transmission hard lines that have rubber hoses attached to the steel hard lines. the hose that goes to the right of the radiator is flow from the transmission into the radiator cooler. and the other that forks to the left is the return line to transmission.
 
veiloctane said:
if you lay down under the front of the left of the truck you will see 2 transmission hard lines that have rubber hoses attached to the steel hard lines. the hose that goes to the right of the radiator is flow from the transmission into the radiator cooler. and the other that forks to the left is the return line to transmission.
Click to expand...

What is the orientation for this, just so we're sure what you're saying? Are you laying with your feet sticking out the front (I assume), or with your feet under the truck? Thanks for the info!
 
Thanks for the response @veilocitane. I have the same question as IanB. I'm assuming since you have to be able to see the transmission lines, your feet is sticking out the front and your head is under the engine bay. Otherwise if it is the other way around and your head is outside, how can you see the transmission lines? So the flow from the tranny to the cooler is on the USPS side of the radiator.
 
are you talking about these lines (see red marking)
Cooler line.webp
 
podiev said:
Thanks for the response @veilocitane. I have the same question as IanB. I'm assuming since you have to be able to see the transmission lines, your feet is sticking out the front and your head is under the engine bay. Otherwise if it is the other way around and your head is outside, how can you see the transmission lines? So the flow from the tranny to the cooler is on the USPS side of the radiator.
Click to expand...

Well, you could be completely underneath the truck and looking up at the tranny cooler lines, on a low creeper with a lifted truck there's no wrong way to be positioned.

The more I think about it, the more I'm certain he meant with his feet sticking out the front of the truck. Hopefully he'll chime in to confirm.
 
feet sticking out the front
 
With the the front skid plate removed...
From the driver's orientation (same as feet out front) - my understanding is the right ATF line enters the radiator from the ATM and the left ATF line (with the rubber loop on JDM diesels) exits and returns cooler ATF to the ATM.

I have installed a front mounted US spec OEM ATF cooler in series with the ATF return line to the ATM.
The reasoning is on cold start-up the ATF is heated by the radiator to 160F-180F (operating temperature) as quickly as possible, and excessive heat is pulled from the ATF by the radiator at temps above 180F. I believe this is the set-up in the US spec gasoline 80's.

All US spec 80's came with the front mounted ATF cooler, but the JDM's did not. The radiator only ATF cooler set-up in the JDM 80's I have found to be completely inadequate for cooling ATF during the long steep grades in North America.


b702012 - that hard loop you have pointed out is the PS steering cooler loop.
 
Glenn-BJ74 said:
With the the front skid plate removed...
From the driver's orientation (same as feet out front) - my understanding is the right ATF line enters the radiator from the ATM and the left ATF line (with the rubber loop on JDM diesels) exits and returns cooler ATF to the ATM.

I have installed a front mounted US spec OEM ATF cooler in series with the ATF return line to the ATM.
The reasoning is on cold start-up the ATF is heated by the radiator to 160F-180F (operating temperature) as quickly as possible, and excessive heat is pulled from the ATF by the radiator at temps above 180F. I believe this is the set-up in the US spec gasoline 80's.

All US spec 80's came with the front mounted ATF cooler, but the JDM's did not. The radiator only ATF cooler set-up in the JDM 80's I have found to be completely inadequate for cooling ATF during the long steep grades in North America.


b702012 - that hard loop you have pointed out is the PS steering cooler loop.
Click to expand...

ATM = ? Automatic TransMission?
 
ATM= automatic transmission
ATF = automatic transmission fluid
 
I fitted a aftermarket try-cool in my hdj81. I would like to see how the toyota factory cooler mounts and fits. Could you please post pics
 
Attach is the pic from Mud of the OEM cooler. It is installed in this orientation.

To make this cooler to be in series wit the radiator cooler:

Question: Is the top port within the red box the INLET? Meaning I will connect a hose from the Radiator cooler outlet on the driver side to this port? And then the bottom port is the OUTLET and I'll connect a hose from there to the return line?

Or it is the reverse?
transcooler1.webp
 
i am 99.5% sure the inlet is the top as the bottom is the outlet back to transmission.


basically you want to daisy chain the hoses... i went from out of transmission to radiator
then out of radiator to inlet of external cooler and then out back to transmission.


transmission out -> radiator in -> radiator out -> external cooler in -> external cooler out -> transmission return.


hope that helps.
 
I installed what I believe to be the hot line (out from radiator) to the top inlet of the ATF cooler (as you have indicated), following the engine radiator coolant direction (top to bottom). I think as the coolant/ATF cools it gets heavier and wants to sink.
 
I did the same as veiloctane but mounted this type of cooler because I had no room for a front mount because of the intercooler. Its still tucked up and out of the way and it works better then the front mount one I had before.

 
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