What have you done to your Tacoma today? 1st Gen Edition

Brahdas, last week I drove the cajon pass (2000’ rise in 17 miles), at about 75 mph. AT got to about 210°, took it out of OD and slowed to 70. Temp quickly dropped to 188°.


Yesterday, I installed an aux cooler inline after the rad. Test drove it up the pass at 90 with the AC maxed, and AT only got to 200°. Great right!!?


So, did I treat a symptom and hide a problem?


If it matters it’s been 40k since AT flush & fill.


Thanks in advance, for sharing your knowledge & experience.
@gearcruncher , @Speedytech7 , @Empty_Lord

 

The Cajon Pass is no joke, I cruise up that pretty often when going to Big Bear since I usually start from the High Desert side outside Hesperia.

I never notice my temps rising more than a few degrees but I'm sure that's because of the manual trans versus auto trans that you're dealing with. Sounds like you did the right thing to resolve the issue, I wouldn't call it hiding a problem. But I don't have an auto so maybe I'm wrong.

The Grapevine is the gnarliest freeway grade in SoCal, I don't know if the elevation gain is as dramatic but the climb is far worse, I hate driving up that in my truck haha.

 

I have those transmissions heat up pretty quick in overdrive going up steep grades you only did something to help it I doubt there’s an issue with the radiator

 

I don't think you were "Hiding a problem." I always take it out of OD when climbing grades.

Running the aux cooler after the rad is exactly where it should be installed. I think you've done everything right.

 

You didn't ask for my take specifically but I don't think you hid the problem. It looks like you directly addressed your problem. Sounds like you did it right by adding that cooler

 

Honestly the trans temp likely went up drastically just because the engine coolant temp was likely around 210 at that point. Being next to the trans cooler likely transfered the heat to the trans fluid

 

How are you seeing your AT temp? I have an ultra gauge but it only shows engine temp as far as I can tell.

 

UltraGauge doesn't show trans temp on 1st gens.
ScanGauges do, unofficially, by using a custom programmed "X-Gauge Commands".

 

That sounds decent to me, what size and style of cooler? Plate and fin or one of the winding pipe styles. 90MPH is no joke cause usually if the load is high enough it'll unlock the TC and turn itself into a heater. 2000' rise in 17mi isn't crazy and 200° is still a bit high to me. But these trans aren't very efficient so it's certainly better. I climbed Grapevine pulling my trailer with the land cruiser, I typically shoot for above 50mph when pulling a load up a pass cause more than that is undue stress but it was raining and I wanted off the pass so I went for 65MPH and ended up heating my exhaust so much the hanger broke but with an absolutely massive trans cooler I only hit 168° on trans temp.

 

Oh really. Well I will have to look into this. My usual way to get AT temp is to touch the carpet on the floor. If it’s more warm then normal I know I should probably change something haha

 

@zero4 got an Ultragauge to show trans temps, he found the code for them

 

Interesting. I’d be curious to see how that works

 

Finishing touch.

 

Have you driven it yet?

 

Coolant temp is measuring temps exiting the engine. It flows through the radiator and is cooled prior to interfacing with the transmission cooler at the bottom.

Regardless of how many transmission coolers you have, when you are accelerating in 4th gear, your lockup clutch will release to help build torque using the torque converter. The issue is, when you are in OD, the torque converter is very inefficient and your temps will immediately spike well over 200. When the lockup clutch engages, you will see an immediate drop of about 10* followed by a continued drop until it levels out to normal operating temp. I have an oversize trans cooler designed for full sized trucks and my temps easily spike to 205* when aggressively accelerating in 4th. When the lockup clutch engages, I generally operate in the 180-190* range.

When you turn off OD, this helps a little initially as your torque converter is more efficient in 3rd gear but the reason you saw a large and immediate drop in temps is more likely because your lockup clutch engaged and your torque converter was no longer pumping fluid so hard. In 3rd gear your transmission isnt under as much load and more readily engages the lockup clutch.

In OD, the lockup clutch will engage aggressively around 50mph with ECT off and with ECT on, it will delay to about 60mph. With OD off, the lockup clutch engages around 55mph.

This is why its always advisable to run with OD off when towing or hauling, especially in the mountains. Also remember, your trans temp is measuring temperature of fluid leaving your torque converter, not overall fluid temp so it will always be volatile/fluctuating based of your torque converter load, regardless of your trans cooler.

Hope that explains everything and puts you at ease.

 

better question: does it even fire up yet / rags removed, @BartMaster1234 ?

 

think you have to have a newer one. but should work. Think there is even instructions on their site for it.

 

Yep, been done about a week. I left for Vegas and just got back the other day, so I’m finishing up the gauges and methanol injection.

https://youtu.be/sUJM9dBkOfE

 

Yes. I removed the remaining debris with a jewelery remover intended for plumbing through the spark plug holes, and I left combustion burn up the rest of it. It fired up on the first turn.

 

1999 and up. I tried on both my 1998’s and it doesn’t report transmission temperature. 1999 is the earliest year I’ve seen it work.