Upgraded trans cooler

I hit 203 yesterday winding my way up the mountain. I threw it in L and she actually dropped to 188. I guess it was hunting for gears and that's why it climbed. Not sure if you guys saw the other thread in the gen 3 section but Toyota apparently dropped the trans cooler for the 2020 Tundra and they are seeing some crazy trans temps. Or maybe it's an option now.

 

How fast were you going?

 

That was the odd part, I wasn't crawling. I was doing 20-25. I've seen temps shoot up to 200 if I'm going real slow in 4WD but that wasn't the case yesterday.

 

Highest Temps at the Trans Pan I’ve gotten so far are around 174° going up grade at around 55 mph. A/C on blast, air temps 85°. Stop and go traffic Pan hovers around 160° range.

Coolant Temps 195° (usual) and 200° (max) always. So far I’ve not seen anything to scare me out of changing from the OEM Cooler based on what temps should read per the experts.

Still haven’t towed with the Gauges. That should be a real test.

 

Almost done, need to grab more hose...

 

Are you guys bypassing the radiator?

 

92° here today. Did some city driving and it was not stop and go type. Transmission Pan temps never broke over 156° with A/C running on flat earth society.

Coolant Temp steady at 195°. Intake Air Temps (while driving at speed) 96° and 115° at idle.

OEM Trans Cooler doing a great job it seems. Still nothing to get me nervous about.

 

normal driving shouldnt be much of a issue. my stock cooler while towing a car was where i decided it was time for a larger cooler (that i have yet to install because other projects are first) pan temp hit the 200 mark while not horrible, its not great

 

It will be a few weeks before I tow again. Now that I’m developing a base line range I’ll be able to determine how towing effects the temps. I’ll be ok with 210° max Pan Temp when towing. Any temp more than 210° and I’ll consider the larger cooler.

Side Note: I need to locate this Transmission Temp Sensor with my eyes. I believe, from memory from the FSM, its up high near all the TC Plates etc. If thats the case, then my readings are TC Temps and not Pan Temps. TC temps are the best case scenario.

 

The 5 speed has 2 temp sensors next to each other. They’re on the valve body circuit one is before (pan) torque converter and after the torque converter

 

2000-2004 a340F Transmission Temp Sensor Location. Looks up high and near all the TC Plates.

 

I find it interesting because we have been having similar weather here (80*-100*) and there is times where I get my Hayden cooler up to 170* under normal driving conditions and up to 195* on my mountain drives. It doesn't stay there for long and cools rather rapidly but I still can't help but wonder what kind of temps the OEM cooler was putting out. I might have a heavy foot but I bet I was pushing the OE cooler past 210*.

I have the derale tstat in hand and I am trying to find time to put it in this week. Also trying to figure out where to mount. After speaking to @Surf_spear_Mex, it makes sense to install this to keep the temp more consistent. When it does spike, the Hayden does cool it very quickly. Hopefully after this is installed, it will regulate the temp to keep it consistent.

 

Yeah. I have had no idea what my Trans Temp has been up until recently. I’m surprised my readings have been so low and am not bummed at the low readings one bit, thus far.

Under 210° is projected threshold for towing. Will know more in the future and report back.

 

Someone with greater knowledge than myself maybe can answer some questions I have. The Hayden cooler is rated for 30K GVW vehicle. Obviously much beefier than our Tundras. In my mind, I would think the this cooler would have no problem keeping things around 160* or below in all conditions.

I’ve been monitoring it every day since the install and as previously posted, on my mountain drives, it was knocking on 194* which I chalked up to ambient air temp, uphill at 70mph for an extended period of time (40ish min pass). Still, I would think this cooler would have no problem keeping things at cooler temps. I also don’t have a baseline from my OE cooler given the same driving conditions.

When I swapped the coolers, I must have added a little too much fluid because the dip stick shows it’s over full by a tad. Would that cause higher temps?

This is my reading from my drive home today, roughly 20 miles, 80*-90* ambient air temp, mix of city/highway, no big hills or anything out of the ordinary. Hottest was 178* and after getting home and idling for 5 min while I checked fluid level, it went down to 145*


Level after the drive home today. It’s a little high but not by much. It’s due for an oil change so I plan on correcting the level when I do the trans service/oil change.

 

These are my opinions only and not expert advice:

1) Your fluid level looks fine. I’ve run mine a tad high (roughly a little below your mark) since discovering the transmission ‘felt’ better in drives. Higher level shouldn’t cause high temps. Too high level is obviously not good. Fresh Fluid is better at cooling.

2) Maybe your new cooler is set too close to the AC Radiator? Most online instruction says to provide at least a 2” gap. My memory says you installed too closely like most of the others pics I’ve seen. If you look at the OEM Trans Rad it has a large gap behind it for air circulation. This may not mean anything, but it might provide insight.

3) Maybe a thin cooler (3/4”) isn’t the best? Maybe a thicker cooler, say like the thickness of the OEM (1.5”), that is slightly larger in area would be better? I posited this theory early on before, but an expert member in all things shot it down. Square inches make a difference when factoring in thickness.

From my research, thin rads are better than thicker ones with no air moving across them. The thicker rads are better with air moving across it. We always have our cooling fan pulling air, so to me a thicker one is better suited.

 

I always value your opinions, input and wealth of knowledge. Expert in headlights I am, expert in trans coolers I am not lol. I think theory #2 may be some of the source, but Hayden only provides foam pads to mount it. One would think that if they wanted it spaced for air flow behind it, it would be mentioned. I have a message out to them to see what they say about spacing away from the AC condensor as well as postion/orientation of the cooler.

Further research lead me to this.

I can't find the original link I found earlier but it was saying when mounting it side ways, the hot side needs to be positioned at the top and the cold side at the bottom. This would keep the hot line feeding through the top and the cool side at the bottom returning it back to the trans. It cited in more detail why but I cannot find it.

 

But.... I will say for my specific application and my current driving conditions, this may have not been a 'must do' modification. I've mentioned this a few times but I also don't have a baseline from my OE setup to do a fair comparison. I will still work to on perfecting the hayden setup but still have my OE cooler just in case.

 

Sure thing bud! I am not expert, but like to read a lot. I also know a lot of doctors. I’d love to get some more drive time on my truck to provide you more baseline input on the temps. It will be a while before I have any long distance trips or towing. Bummed on my phone battery dying the other day, as I had a nice distanced trip with about 850 pounds in the bed. Would have been great data points.

Per your post #167, I understand. I’m ready to jump on board with a better cooler if it works! The reason for me buying the ODB Reader is to test the waters before jumping in.

 

I think it does work but I need to understand more why it fluctuates temp so much. I did receive a response back from Hayden stating that they do not recommend mounting it with the fittings pointing down but they didn't speak to why the temp was jumping around so much. I am going to try to get it remounted and serviced this week before my out of town trip but it may be pushed off.

 

For certain rads, orientation is critical. Like PHM mentioned, so can proximity to other rads. If air flow is restricted out the back, air won't be flowing over the fins. As I posted on the first page of this thread, the Cool-Max rads can be mounted in any orientation. Looks like the Hayden rads can't be. My guess is your problems will go away when you reorient it and also give it more space between it and the rad behind it. I think your problem isn't that the rad isn't working, it's more that it isn't being able to work.

 

This reminds me of a piece of advice a heavy duty transmission tech once told me, he said try to avoid shutting off your vehicle immediately after extended highway runs, especially if towing. He explained that idling for a few minutes would cool down the transmission significantly. I keep this in mind when getting fuel on long trips since some fuel stops may be right off the highway/interstate.

 

Got it done tonight. Only got a short drive but the real test will be tomorrow when I’m headed up the hill.

 

95° Ambient Temps today.

30 minutes of stop and go driving with A/C on full blast (which to me seems to add about 10° to the Trans Temp after some unscientific testing).

 

I've never seen stop and go traffic, no matter the ambient temp, to be the source of an engine or trans temp problem. It's always either towing up a grade (lots of work with airflow) or slow crawling (less work with no/limited airflow) that leads to problems. If you're having problems in stop and go traffic, you have bigger problems than a new/bigger rad for your trans will solve.

 

I'm interested to hear how this works. How much space between the two rads?

 

I’ve been meaning to update this but been out of town and of course work. I did get a mountain run in and these were my results. Ambient temps were 90*. AC on the whole time.

Initial warmup: In town driving, temps were solid at 150*. I opened the hood and both hoses before the thermostat were warm, both after were cold which indicates that the thermostat was doing exactly what is supposed to. Keep the cooler blocked off till temps were warmer.

Highway driving: Cruise set at 80mph, pretty much flat driving, temps solid at 164*. About 60 min drive.

Heading up the pass: Temps were pretty steady and once it hit 185* on the gauge, it immediately started dropping to about 160*. Prior, it was running up to 194* so once it hit temp, it dumped the fluid into the cooler immediately reducing the temp.

Once at the top of the hill: Idling at the top of the jobsite for 15min, it cooled down to 140* and stayed there.

Mountain driving: Speed at 45mph, mix of hills, curves, some traffic etc, temp stayed at 150*.

Conclusion/thoughts: The Derale 13011 is probably a must to if you are going to upgrade your cooler to an oversized unit like the

$58 Hayden 679 Universal 11” Rapid-Cool Add-On Transmission Cooler to Enhance Cooling (not for direct replacement of the factory unit)

Hayden 679. It made the the temps much more stable and consistent. I’m not sure how it would have performed in the colder months but according to @Surf_spear_Mex, it ran too cold. I think mounting it sideways also helped keep the fluid at a more consistent temp.

Now was this swap needed? After doing all this, I think for my application, the OEM probably was doing a decent job except when going up to the mountains. I really wish I would have established a baseline with the OEM unit with my driving patterns and trips to see how it compares to the Hayden. I do have a piece of mind using the derale and Hayden unit combined in the sense that will never run too cold and never run too hot. Combined, they work really well together. The truck seems to like the cooler temps and it’s nice having the transmission warm up faster on the short jogs in town.

 

Making a new mount for the Thermostat. I Used what I had laying around the house at the time, I dont like the way the old one looks so Im making a new one.
I'll update pics when I'm done..

 

@SouthPaw

It was 94° here today and was doing some extended city driving. It was a mix of stop and go with a little cruise time. Tried Spirited Driving on some runs. Highest Trans Temp was 165° which would drop to 150°ish when cruising 55mph. Rad Coolant Temps are extremely stable/consistent in the 195°-200° Tight Range.

Flat Earth Driving. With AC on.

 

Finished up my new bracket, I still want to replace the phillips head screws with button heads.
Also wrap the rest of the hoses.

 

@Professional Hand Model, Referencing your temp posts, how long are you driving for? I’m curious to know as your temps are quite low compared to mine but I’m also taking 2+ hours one way trips.