Transmission Temps: Observations and Revelation

[stanleybb50]

I'll verify which where the temp report is coming from this weekend but when I was shooting the system with in infrared gun last week with the temp reading 240F I am almost positive the temp reported was close to the reading my IR gun was showing when shooting the hot fluid coming from the trans in to the primary radiator oil cooler, then coming out about 220 and going through the secondary external oil cooler and coming out around 200. I'll take notes next time to try to make sure I get the right answer.

Of interest, my folks are going to visit this weekend and we're going to drive up to Horseshoe Meadows which is a serious climb from about 3800' to 10,000' in 19 miles with most of the climb taking place in under 10 miles. They own a 2008 V6 Limited 4x4 while I own a 2007 V6 SR5 4x4. I have an aftermarket transmission cooler, they do not. I have a second ScanGaugeII and I'd like to hook it up and compare readings during the climb. This would be as close to an apples-to-apples comparison as I know how to get.

My plan was to run two nearly identical 4Runners, one with an aftermarket cooler (mine) and one without (my Dad's) with a ScanGaugeII attached to both to see what difference in transmission temps there was. Unfortunately I couldn't locate my second ScanGaugeII so the comparison didn't happen. I'll post it up if the chance comes up in the future.

Any update on this by chance?

 

[OrdnanceMarine]

Any update on this by chance?

Ourdoor season is upon us but the other 4Runner owner (my parents) just took delivery of a brand new Lazy Daze RV of which they will be towing my old CR-V behind it since you can't tow the 4Runner so my guess it that it may be less likely that I get this data any time really soon. I did, however, locate both of my ScanGaugeIIs so I can do the comparison any time. I will definitely update. Since the CR-V lacks real offroad capability perhaps they will have my brother drive their 4Runner seperately so they can offroad with my family (I don't have plans to spend all day towing their car through the rough stuff or smelling the boiling ATF that would be the result of taking that car on extended steep climbs).

Bottom line is that the cooler makes a significant difference but doesn't eliminate all concern when towing. I found that I had to limit things on the very steep and long drive up to Bristlecone to keep temps below 240F.

 

[Scotty_h]

Just some 2 cents... I triggered my atf temp warning light at 300 degrees while towing a camper... your Toyota technician is right.

 

[JB.]

Just some 2 cents... I triggered my atf temp warning light at 300 degrees while towing a camper... your Toyota technician is right.

Interesting, thanks for posting.

How'd you get the temp, scangauge?

 

[stanleybb50]

Just some 2 cents... I triggered my atf temp warning light at 300 degrees while towing a camper... your Toyota technician is right.

Interesting, thanks for posting.

How'd you get the temp, scangauge?

Also very curious if that was a Scanguage temp reading or otherwise.

Also, I would highly recommend a couple drain/fills or a flush if you haven't already. Basically cooked the fluid there.

V6 or v8? (Mostly wondering if you had/have an external trans cooler or not).

 

[Scotty_h]

Temp was monitored through a scan gauge ii. I have record high temps... 260 in the mountains with nothing in tie, 220-230 on KY hwys at 70 MPH. I am on 33's with a toytec lift, shrockworks bumper and winch, sliders. The truck feels heavy but the transmission runs flawlessly. For now I suppose. I have two coolers on. One is the small b&m and the other is the larger one they make. It does make me nervous. I'm keeping an eye out for a donor vehicle

 

[stanleybb50]

Temp was monitored through a scan gauge ii. I have record high temps... 260 in the mountains with nothing in tie, 220-230 on KY hwys at 70 MPH. I am on 33's with a toytec lift, shrockworks bumper and winch, sliders. The truck feels heavy but the transmission runs flawlessly. For now I suppose. I have two coolers on. One is the small b&m and the other is the larger one they make. It does make me nervous. I'm keeping an eye out for a donor vehicle

Wow - that's hotter than mine was getting with the stock v8 cooler when towing a 4,500 lb travel trailer! Like much hotter. Even in hard core stop/go Pittsburgh bridge traffic, I've never gone over like 205. Towing I had hit 230.

I literally just installed the bigger B&M cooler the other day, so I'll try to report back on the difference vs the stock cooler.

Assuming you must have a v6 then?

 

[OrdnanceMarine]

Temp was monitored through a scan gauge ii. I have record high temps... 260 in the mountains with nothing in tie, 220-230 on KY hwys at 70 MPH. I am on 33's with a toytec lift, shrockworks bumper and winch, sliders. The truck feels heavy but the transmission runs flawlessly. For now I suppose. I have two coolers on. One is the small b&m and the other is the larger one they make. It does make me nervous. I'm keeping an eye out for a donor vehicle

You make the temps I see towing at MGVW up seriously steep Sierra Nevada mountain highways and roads in July and August look like child's play! I'm curious how long your transmission will last under these conditions. Please keep us updated!

 

[stanleybb50]

Update on my "bigger" transmission cooler on the way home from work today is that it does seem to cool a little better than the stock v8 cooler, but maybe 10 degrees cooler under similar situations? (Negligible IMO). Might cool down a tad faster too after a hill?

Not worth the trouble installing unless you have a v6 in my opinion. I'll post back after more and more trips / comparisons, but the change didn't seem all that great today at least.

(*B&M 70264 vs stock v8 cooler)

 

[OrdnanceMarine]

Update on my "bigger" transmission cooler on the way home from work today is that it does seem to cool a little better than the stock v8 cooler, but maybe 10 degrees cooler under similar situations? (Negligible IMO). Might cool down a tad faster too after a hill?

Not worth the trouble installing unless you have a v6 in my opinion. I'll post back after more and more trips / comparisons, but the change didn't seem all that great today at least.

(*B&M 70264 vs stock v8 cooler)

Was this towing a heavy load?

 

[stanleybb50]

Was this towing a heavy load?

No not at all. Just the usual commute home. I think your next comment wood likely be valid, in that I should give it time and compare towing temps as well. Fact is I didn't vet it out and definitely not enough comparisons, and need more time for a true report back on it.

I'd think the best setup would be the v6 setup with an aftermarket cooler though that utilizes the rad and the cooler. Unless I just didn't take the time to check where my lines are going (which I really didn't - I just connected to the existing hard lines there, I'm under the impression that the v8 doesn't go into the radiator, but only the cooler). Am I right there?

Here it is installed:

 

[OrdnanceMarine]

No not at all. Just the usual commute home. I think your next comment wood likely be valid, in that I should give it time and compare towing temps as well. Fact is I didn't vet it out and definitely not enough comparisons, and need more time for a true report back on it.

I'd think the best setup would be the v6 setup with an aftermarket cooler though that utilizes the rad and the cooler. Unless I just didn't take the time to check where my lines are going (which I really didn't - I just connected to the existing hard lines there, I'm under the impression that the v8 doesn't go into the radiator, but only the cooler). Am I right there?

All ATs that I am aware of route the fluid through the radiator whether or not they have an external cooler.

You're also right that I would recommend a comparison where you are actually fully loading up your systems and making that comparison when everything is heat soaked.

 

[stanleybb50]

All ATs that I am aware of route the fluid through the radiator whether or not they have an external cooler.

You're also right that I would recommend a comparison where you are actually fully loading up your systems and making that comparison when everything is heat soaked.

I will say that my commute is pretty hard on a car from downtown Pittsburgh, 13 miles to the "South Hills" of Pittsburgh (and it takes an hour, obviously dealing with a lot of hills - hence the name). I usually reach about 205 as a max on a day like today, but my max was 200 today with the new cooler. (That's the max - under most conditions today, it was no higher than about 190).

Oh and it's so hard to see where those lines are going under the hood - you're probably right in that it likely does route through the radiator. I just didn't get any visual confirmation thereof - lol.

 

[Scotty_h]

Wow - that's hotter than mine was getting with the stock v8 cooler when towing a 4,500 lb travel trailer! Like much hotter. Even in hard core stop/go Pittsburgh bridge traffic, I've never gone over like 205. Towing I had hit 230.

I literally just installed the bigger B&M cooler the other day, so I'll try to report back on the difference vs the stock cooler.

Assuming you must have a v6 then?

yeah, we are talkng about a 99 3rd Gen with the v6 and 280K on it. Shifts fawlessly.... Hoping it will last

 

[stanleybb50]

yeah, we are talkng about a 99 3rd Gen with the v6 and 280K on it. Shifts fawlessly.... Hoping it will last

Ohhh - I think we all thought you were talking about a 4th Gen. Gotcha. I'd just try to keep up on the fluid changes then. Seems like you're doing everything you can with the dual coolers!

I hope she lasts another 10 years!

 

[4RunnerFan]

Right away I picked up that if the transmission was in 4th or 5th and the torque converter was locked up then the trans temp would be around 175 plus or minus about 5 degrees. When the torque converter unlocked the transmission temp would immediately begin to climb. The longer the grade, the more the climb, getting up to around 200 before I'd either finish the climb or if it was in 5th gear, before I'd bump it to 4th and once the torque converter locked up, the temp would quickly drop back to ~175. This was very predictable and allowed me to bump the transmission in to 4th just ahead of an incline so I could both maximize fuel economy while preventing a mid-hill shift from 5-unlocked to 4-unlocked and helped keep the temp down.

The above was taken from the original post, and my question here does nothing more than expose my complete ignorance on these matters, but because of my curiosity I just can't resist asking.

With only stock instruments, how can one tell when the torque converter is locked? I imagine it must lock at some point when the throttle is held fairly steady, and unlocks when we demand more power, but is there a way to know exactly when the lock occurs?

It sounds like we need to prevent the torque converter from unlocking/locking at inappropriate times during a hill climb. My '08 T4R owner's manual says one should always tow in 4th gear, but I've often ignored that advisory by putting it in 5th when going down a hill or driving long stretches of level roadway. (Note: the hills we're talking about here in Minnesota are nothing compared to what the OP described). I would put the gear selector back in 4th when at the base of another hill climb thinking the change in gears allowed for higher RPM which, in turn, allowed the tranny fluid to be pumped faster through the radiator to prevent overheating. Wrong?

 

[JB.]

With only stock instruments, how can one tell when the torque converter is locked? I imagine it must lock at some point when the throttle is held fairly steady, and unlocks when we demand more power, but is there a way to know exactly when the lock occurs?

It sounds like we need to prevent the torque converter from unlocking/locking at inappropriate times during a hill climb. My '08 T4R owner's manual says one should always tow in 4th gear, but I've often ignored that advisory by putting it in 5th when going down a hill or driving long stretches of level roadway. (Note: the hills we're talking about here in Minnesota are nothing compared to what the OP described). I would put the gear selector back in 4th when at the base of another hill climb thinking the change in gears allowed for higher RPM which, in turn, allowed the tranny fluid to be pumped faster through the radiator to prevent overheating. Wrong?

The main thing you need to be careful with is not manually downshifting below 4th gear and forgetting about it. As you saw from OrdnaceMarine's posts, once in 4th and locked, temps start to drop pretty rapidly, so even if you're climbing a long, steep mountain, there will probably be times when the transmission can shift to 4th and allow some cooling.

Here's a quote from my '05 manual.

Do not continue hill climbing or
hard towing for a long time in the
“3”, “2” or “L” position. This may
cause severe automatic transmission
damage from overheating. To
prevent such damage, “4” position
should be used in hill climbing or
hard towing.

As far as knowing when it's locked or not, you just have to familiarize yourself with the rpms, speed, and gear. For instance, at 50mph in 4th gear I'm just about dead on 2,000 rpms. Downshifting to 3rd would put me at about 2800 so if I see the rpms at about 2300, I know it's unlocked. If you watch, you can see and hear it unlocking. In 4th though, (in my usage) it mostly wants to stay locked.

 

[stanleybb50]

I think it must be easier to pick up with my Magnaflow Muffler.. But you can feel and see when it locks vs unlocks. When it unlocks, it's almost like a downshift, but not as "big" of a change as a full downshift from like 5th to 4th or 4th to 3rd. Make any sense? When it's locked and stays locked, even when you give it a little gas... Hard to explain...

Here's an f150 thread I found when doing a Google:

http://www.f150online.com/forums/tr...l-if-my-torque-converter-locked-unlocked.html

 

[OrdnanceMarine]

As far as knowing when it's locked or not, you just have to familiarize yourself with the rpms, speed, and gear. For instance, at 50mph in 4th gear I'm just about dead on 2,000 rpms. Downshifting to 3rd would put me at about 2800 so if I see the rpms at about 2300, I know it's unlocked. If you watch, you can see and hear it unlocking. In 4th though, (in my usage) it mostly wants to stay locked.

This has been my experience, in that you just have to spend enough time behind the wheel to get to know how it works. What I find is that I end up rarely using cruise control when I'm towing because it doesn't take much at all to trigger the transmission to unlock the torque converter. What I often find that I have to do is only open the throttle so far to keep the torque converter from unlocking. If I need the extra power then I will manipulate the throttle or selector lever to get a shift to 4th and then manipulate the throttle to get the torque converter to lock up in 4th. I have a ScanGaugeII so I can keep an eye on throttle position and this helped me learn when the transmission usually will unlock or shift.


I really would like our transmission to lock in 3rd as I'd be able to cruise up some pretty steep grades and never break 200F.