External Transmission Cooler. Temp questions.

[slothy49]

Installed a Hayden 698 on my 01 limited using Iconic Fabrication’s bracket. Shout out to them by the way the kit was great. Anyways, I installed in series with my new oem radiator transmission cooler. The send line goes to the oem cooler, out to the Hayden, back to the transmission.

I was expecting this to really help with temps during a 3 week road trip through the western US. However during the trip, I would consistently see transmission temps climb to 210-225 during mountain passes. Mind you outside temps were anywhere from 85-105f and were loaded up with a full load of gear and camping equipment. Even got up to 240 once. Am I overreacting or am I still running too hot?

 

[jgue467]

So the hot line go to the radiator then out to your hayden and then back to the trans - correct ? Is the external mounted directly onto the AC condensor or a few inches in front ? I put mine right on top of it because the instructions said it would be most effective there and less a few inches in front.

I have a hayden 699 (just a little bigger) - I don't have mountain passes around me just hills in the 200' range. It cruises 80 at 172. Repeated SG will get it to 204 for a few seconds then down to 185. Temps here are about 100.

If towing I use OD override going up the hills - that really helps to keep it under 200 up hills while towing.

 

[slothy49]

So the hot line go to the radiator then out to your hayden and then back to the trans - correct ? Is the external mounted directly onto the AC condensor or a few inches in front ? I put mine right on top of it because the instructions said it would be most effective there and less a few inches in front.

I have a hayden 699 (just a little bigger) - I don't have mountain passes around me just hills in the 200' range. It cruises 80 at 172. Repeated SG will get it to 204 for a few seconds then down to 185. Temps here are about 100.

If towing I use OD override going up the hills - that really helps to keep it under 200 up hills while towing.

It’s mounted in front. In place of the factory driver side horn. Like this.

https://imgur.com/JlW2Dxk

 

[phattyduck]

I'm assuming you are checking transmission temps with the OEM sensor via OBD-II? If so, that is the HOTTEST the trans fluid gets. The OEM sensor is on the outlet of the trans, after it goes through the (probably unlocked) torque converter. I have a feeling that MOST of the fluid is much cooler than that.

If you are getting such high temps (on the highway), just turn off OD and the torque converter will lock and temps will drop very quickly (since you do have good cooling). If it is happening offroad, that means you should be in 4LO, most likely...

I would put that cooler behind the bracket, if possible though. The radiator fan can just pull air right around it when it is that far from the rest of the cooling package. I even re-mounted my AC condenser closer to the radiator so that I had room for everything close together.

Here's how close mine is:

-Charlie

 

[2TH4IST]

I had a Hayden 699 with a fan a while ago. It was okay, on road driving it was always in the 190's, up hill it would get 205 constant. I had a 180° thermo switch which would turn on the fan. I had that mounted on the return of the cooler. I bypassed the radiator, well I have the koyo aluminum radiator so no trans cooler in there.

Now granted I live in socal, so I have steep grades and over 100° summers where I live.

Since I had to redo almost everything in front of the ac condenser when I made the coastal bumper. So I went full over kill and put mishimotos 2 pass medium size oil cooler on the trans. I also put a temp sensor on the return pipe. I have the scan gauge for outlet temp. 180-205° outlet and 130-145° return. That's nuts, a drop of 50- 60°. I'd say it works damn good.

Also I foam taped everything, trans cooler to the ac condenser, ac condenser to radiator and lastly the rad to fan shroud.

 

[Endlessblockades]

How do you like the KOYORAD?

 

[2TH4IST]

It's great. Nice build quality and works like a champ. Stays under 193° any load or outside temp. Only downside is if you want to keep the stock trans cooler. It doesn't have it. It's the 4th car I have ran koyo on. No worries of aging plastic end tanks.

 

[Mgyver1]

I think you’re letting the torque converter unlock too much. I disengage cruise and work the engine watching & listening to the rpm’s and turning off overdrive to keep the transmission temp down. You can see when your torque converter unlocks because the RPMs will jump up slightly and then your trans temp will start climbing and climbing. Modulate your throttle and speed to find a happier gear for the engine and you should be able to keep your temps more reasonable.

 

[19963.4lsr5]

I'm assuming you are checking transmission temps with the OEM sensor via OBD-II? If so, that is the HOTTEST the trans fluid gets. The OEM sensor is on the outlet of the trans, after it goes through the (probably unlocked) torque converter. I have a feeling that MOST of the fluid is much cooler than that.

If you are getting such high temps (on the highway), just turn off OD and the torque converter will lock and temps will drop very quickly (since you do have good cooling). If it is happening offroad, that means you should be in 4LO, most likely...

I would put that cooler behind the bracket, if possible though. The radiator fan can just pull air right around it when it is that far from the rest of the cooling package. I even re-mounted my AC condenser closer to the radiator so that I had room for everything close together.

Here's how close mine is:

-Charlie

Who makes your trans cooler? It looks sweet.

At one time I was looking for a thermal couple washer to put under the drain plug to monitor the oil temp.

 

[3bears]

i run the 698. However I live in very cool climates. the 698 has the internal bypass so oil does not go through cooler if it is cool. But I dont know what temp hayden has it set to do that

 

[phattyduck]

Who makes your trans cooler? It looks sweet.

At one time I was looking for a thermal couple washer to put under the drain plug to monitor the oil temp.

Its a Tru-Cool LPD4921, comes in a kit with a thermostat bypass. (LPD49211 comes without the thermostat)

Thin and wide means it can be mounted in the upper grill airflow for max cooling.

-Charlie

 

[Endlessblockades]

Its a Tru-Cool LPD4921, comes in a kit with a thermostat bypass. (LPD49211 comes without the thermostat)

Thin and wide means it can be mounted in the upper grill airflow for max cooling.

-Charlie

That kit looks like a great choice. I am thinking about handing down my compact Tru-cool to a friend and going with one of those and a radiator without integrated transmission cooling. I went with an all-plate design, but it turns out I DON'T wheel with a-holes shooting rocks at my grille! The fin and plate design looks good. Did you mount it with brackets that came with it or your own design?

 

[phattyduck]

Did you mount it with brackets that came with it or your own design?

I used the stuff from the kit, modified and painted black. You can see them in the pic above. They are bolted to the AC condenser, so it is rubber isolated just like the condenser.

-Charlie