Progressively Rising Transmission Temperatures

[Rock_Rat]

Just looking for some input here to see what you guys would do next.

Lately, I've been noticing my transmission temps rising to a level I'm not very comfortable seeing. I did the long trip out to flagstaff for the Expo, and most of the parks in Utah including down in Canyonlands and MOAB and returned home with pretty decent temps - Under 200 almost consistently.

Keep in mind I still have the winch solenoid and both PIAA lights mounted up front and they didn't affect my temps as far as I know of.

Lately I've been noticing my temps on the rise, especially during these hot afternoons when the ambient temps are pushing 90° and higher. Yesterday we topped out at 104°.

Details:

• 4.88's
• 33" tires
• SC'd
• Headers
• 170° thermostat
• B&M 70826 cooler in line with the radiator
• Toyota red/distilled - newish radiator (2 years old?)
• Transmission fluid - OEM (not synthetic) Nice and red.
• Drain and fill every other oil change.
• No IPT or Transgo mod yet

Things I'm considering:

• Complete replenish of my radiator
• Replace fan clutch
• Run cooler by itself and bypass radiator
• Install larger cooler
• Total replacement (not a flush - sorry guys but I don't trust them) of fluid with synthetic
• Transgo/IPT kit

Any thoughts on this would be greatly appreciated. Here's a few pics:

Here's where I was yesterday afternoon just before getting off the freeway to head home. Pretty hot and I had the AC on full blast. I also just had to pass a couple of trucks and quickly get into my exit lane. About 30 miles driving and in traffic.


Top of my 3 mile climb just before entering my private drive. Drove up hill with the AC off and OD off. It cools down very fast.


Here's where I was at this morning after a 25 mile drive. For the most part, once it was warmed up, it stayed around 179 - 183 most of the way.

 

[thegipper]

Those tranny temps seem perfectly normal to me.

Synthetic fluid is much more resistant to breaking down and "burning" at higher temperatures. Other than switching to a full synthetic (for piece of mind) I don't think you really need to do anything else IMHO.

By the way, is that 366k miles all on the original motor/tranny?

 

[phattyduck]

You can expect temps 'around' 100*F above ambient with the stock trans cooler.

First, are you sure your torque converter is locked when cruising on the highway? (it looks close from my calculations of your gearing, but maybe not?)

If you are pushing the truck hard with the torque converter unlocked, trans temps can easily get to what you are seeing. I noticed this on some grades around Death Valley in the spring (~90*F or so). If your driving conditions are like this regularly, you'll probably want to add a suplimental trans cooler to keep things closer to 200*F in your 'normal' harsh conditions.

Overall though, I'd be more concerned that your engine temp is all over the place... It should be pretty rock solid once warmed up.

-Charlie

 

[LittleCaesar]

First, if the fan clutch is original, then replace it stat. Or at least I would. The fluid in it by this age is all but gone.

Then burp the cooling system well, such as make sure all bubbles are out of the cooling system. Age of the water pump? As Charlie said the lack of a small variance between coolant temps is concerning, and may be the reason behind the rising tranny temps. What coolant temps are you used to seeing?

I'd do at least a 4 quart ATF drain and fill. ATF doesn't cost much. New fluid equals a happy tranny, well at least most of the time.

 

[DK327]

I personally wouldn't bypass the radiator to just use the external trans cooler, this will most likely cause even a bigger temp spike; with current setup you have 2 trans coolers, the radiator and the in-line cooler unless a problem with the trans cooler in the radiator is causing the issue...

I second the recommendation of trans drain and refill (4QT's) and find out the age of the water pump. Replacing fan clutch is a good idea but might not make any difference to alleviate the problem you're experiencing.

If I were to get a bigger auxiliary cooler, I'd keep it inline still and probably get one with electric fan.

Oh and 366,715!!! ****ing awesome!

 

[Rock_Rat]

Those tranny temps seem perfectly normal to me.

Synthetic fluid is much more resistant to breaking down and "burning" at higher temperatures. Other than switching to a full synthetic (for piece of mind) I don't think you really need to do anything else IMHO.

By the way, is that 366k miles all on the original motor/tranny?

If I wasn't the original owner I would probably agree with you, however, having monitored the temps like a hawk over the years, I'm definitely see a significant rise in temperatures. Here's some info from one of my posts back in March 2016. (Looking at the RPM's this was before the gears, SC, and headers.)

March 2016
Average speeds between 71-78
RPMS around 2300 or so
184° - 186° for water temp
145° - 159° for tranny temps

Inclines
RPMS upwards of 3000
184° - 186° (Hardly ever changed)
158° - 178°

Steeper Climbs with OD still off but ECT on
186° - 190°
189° - 202°

Once I turn the OD off the tranny temps drop to around 179°

Tranny temps creep up to above 200° for me everyday on my 3 mile drive up my mountain.

Yes, all original miles on everything. Oil changes!!!!!!!!!!!

You can expect temps 'around' 100*F above ambient with the stock trans cooler.

First, are you sure your torque converter is locked when cruising on the highway? (it looks close from my calculations of your gearing, but maybe not?)

If you are pushing the truck hard with the torque converter unlocked, trans temps can easily get to what you are seeing. I noticed this on some grades around Death Valley in the spring (~90*F or so). If your driving conditions are like this regularly, you'll probably want to add a supplemental trans cooler to keep things closer to 200*F in your 'normal' harsh conditions.

Overall though, I'd be more concerned that your engine temp is all over the place... It should be pretty rock solid once warmed up.

-Charlie

Torque converter is locked, however, I'm expecting it to go one of these days, weeks, months, or years. I've been resetting a P0770 code (Overdrive solenoid) since 2011. My RPM's are closely matching my gears according to the tables I've looked at. I think I'm going to start with a complete fluid change first.

First, if the fan clutch is original, then replace it stat. Or at least I would. The fluid in it by this age is all but gone.

Then burp the cooling system well, such as make sure all bubbles are out of the cooling system. Age of the water pump? As Charlie said the lack of a small variance between coolant temps is concerning, and may be the reason behind the rising tranny temps. What coolant temps are you used to seeing?

I'd do at least a 4 quart ATF drain and fill. ATF doesn't cost much. New fluid equals a happy tranny, well at least most of the time.

Yes, the fan clutch is original. Top of my list since I believe I saw some pretty impressive numbers from [MENTION=115590]StreetCreeper[/MENTION] (i believe it was him) a while back after he changed his. Complete fluid change is on the list as well. The water pump is OEM and I changed that at 309K miles when I did the timing belt. With the new thermostat for the SC I rarely saw the temps go above 186 and never in the 200's. Under normal driving conditions I'm usually around 179 to 183 with similar or lower transmission temps. Recently, I've been seeing them a bit higher - 186-195. Tranny temp stays under 200 but takes a serious spike up hill.

I personally wouldn't bypass the radiator to just use the external trans cooler, this will most likely cause even a bigger temp spike; with current setup you have 2 trans coolers, the radiator and the in-line cooler unless a problem with the trans cooler in the radiator is causing the issue...

I second the recommendation of trans drain and refill (4QT's) and find out the age of the water pump. Replacing fan clutch is a good idea but might not make any difference to alleviate the problem you're experiencing.

If I were to get a bigger auxiliary cooler, I'd keep it inline still and probably get one with electric fan.

Oh and 366,715!!! ****ing awesome!

Thanks for your input. I've read all kinds of pros and cons on the tranny cooler and you're input along with the cooler environment in the Northwest is exactly the reason I went in-line with the radiator. As you said, I think I'll stay that route. Just been playing around with some thoughts. I think a fan clutch replacement wouldn't hurt, despite it's minimal gains and perhaps a flex fan (only thinking about it). It can only help improve the engine and I'll take whatever improvements I can. If I go with the electric fan, I'll get with [MENTION=63700]Rcastle[/MENTION] and we'll install one similar to his along with the 3-core radiator he just installed.

 

[JayRolla]

Like people stated normal temps are about 100* above ambient temp and thats with normal driving. With a load and or incline you can expect 15-50* increase depending on the situation. The fluids can hit over 300* in the tq converter. So I dont see much of an issue.

What do you think us 96-97 guys do. We are not able to log those temps anyways. So we dont even care about the trans temps.

 

[Rock_Rat]

Like people stated normal temps are about 100* above ambient temp and thats with normal driving. With a load and or incline you can expect 15-50* increase depending on the situation. The fluids can hit over 300* in the tq converter. So I dont see much of an issue.

What do you think us 96-97 guys do. We are not able to log those temps anyways. So we dont even care about the trans temps.

Yea, I'm probably overly concerned because of the mileage I have on this rig.
Just trying to stay ahead of any potential failures and stay tuned to any possible tell-tale signs of an impending failure. Sure would like to be proactive than reactive.

 

[thegipper]

I installed a glowshift tranny temp gauge on my 97, love it.

 

[19963.4lsr5]

So your converter is locked going up those hills? As in you give it more throttle and the mph and rpm rise together rather than a instant rise in rpm and a slow increase in mph.


Sent from my iPhone using Tapatalk

 

[phattyduck]

Here's some info from one of my posts back in March 2016. (Looking at the RPM's this was before the gears, SC, and headers.)

March 2016
Average speeds between 71-78
RPMS around 2300 or so
184° - 186° for water temp
145° - 159° for tranny temps

Inclines
RPMS upwards of 3000
184° - 186° (Hardly ever changed)
158° - 178°

Steeper Climbs with OD still off but ECT on
186° - 190°
189° - 202°

Once I turn the OD off the tranny temps drop to around 179°

Tranny temps creep up to above 200° for me everyday on my 3 mile drive up my mountain.

Weak fan clutch would explain what you are seeing... Especially since your truck used to get these numbers (those are also pretty much the numbers I see on my truck, but it is essentially stock).

Goes like this: Weak fan clutch doesn't allow radiator to cool the coolant as much as it should, leaving hot coolant in the bottom tank. At that point, both the engine and trans temps will rise more than than they should.

Should be an easy fix!

-Charlie

 

[theesotericone]

What do you think us 96-97 guys do. We are not able to log those temps anyways. So we dont even care about the trans temps.

Well, I do care about my 97 so I put an Auto Meter gauge in when I added the trans cooler in-line with the radiator. Simple and worth it for the piece of mind alone. But if you trust your idiot light that's cool too.

 

[alumarine]

Considering you are doing a drain and fill frequently you should be just fine.

There is a time / temperature relationship with the fluid but you wouldn't even be near damaging the fluid with your drain refill freqency.

 

[LittleCaesar]

From someone who has to deal with high humidity and heat usually every summer I can tell you the clutch needs to be replaced.

In the Southern US if one gets more than fifteen years out of a fan clutch they are just living on borrowed time. The first thing that needs replacing if one keeps an aged auto here is the cooling system, from top to bottom. I know the PNW is seeing record temps this week so try and stay cool. Plus UW football isn't too long away.

 

[JayRolla]

Well, I do care about my 97 so I put an Auto Meter gauge in when I added the trans cooler in-line with the radiator. Simple and worth it for the piece of mind alone. But if you trust your idiot light that's cool too.

I trust my 4runner. That is a nice see you got. I'm sure if I towed I would worry more.

 

[theesotericone]

I trust my 4runner. That is a nice see you got. I'm sure if I towed I would worry more.

I don't tow. I do wheel a lot. The area I live in can take you from 4000' to 11000' in as little as 4 miles. Since getting larger tires I had my idiot light come on twice while wheeling up steep grades. I wanted to stop that from happening so I installed a trans cooler with a fan. I wanted to see what my actual temps where so the aftermarket temp gauge was the only option.

I don't know what my temps where before but right after I installed the gauge and cooler I went up the same grade that caused the idiot light to go on. Same air temps, same rig, same speeds, same driver. With the fan on my temps never got above 190. It's a 4 mile pull from 4400' to 10500'.

 

[JayRolla]

I don't tow. I do wheel a lot. The area I live in can take you from 4000' to 11000' in as little as 4 miles. Since getting larger tires I had my idiot light come on twice while wheeling up steep grades. I wanted to stop that from happening so I installed a trans cooler with a fan. I wanted to see what my actual temps where so the aftermarket temp gauge was the only option.

I don't know what my temps where before but right after I installed the gauge and cooler I went up the same grade that caused the idiot light to go on. Same air temps, same rig, same speeds, same driver. With the fan on my temps never got above 190. It's a 4 mile pull from 4400' to 10500'.

I've never had the idiot light come on. Where I live we can go from 6k to 25k in a few miles. All rock crawl and 4lo entire way. Guess I'm lucky.

 

[theesotericone]

I've never had the idiot light come on. Where I live we can go from 6k to 25k in a few miles. All rock crawl and 4lo entire way. Guess I'm lucky.

25k? You live in Nepal?

Seriously though, your not lucky your smart. 4lo will keep you cool. I keep it in 4hi until I need to engage 4lo. I like to go as fast as conditions allow. Which is pretty fast usually.

 

[Rock_Rat]

So your converter is locked going up those hills? As in you give it more throttle and the mph and rpm rise together rather than a instant rise in rpm and a slow increase in mph.


Sent from my iPhone using Tapatalk

No, I'm talking about highway driving. Torque converter is running fine. Up hill heading home I have the OD pushed in. Helps to drop the temps.

 

[Rock_Rat]

From someone who has to deal with high humidity and heat usually every summer I can tell you the clutch needs to be replaced.

In the Southern US if one gets more than fifteen years out of a fan clutch they are just living on borrowed time. The first thing that needs replacing if one keeps an aged auto here is the cooling system, from top to bottom. I know the PNW is seeing record temps this week so try and stay cool. Plus UW football isn't too long away.

Thanks, looks like I'm ordering a fan clutch tomorrow. Still might do a complete coolant system flush and replace some ATF. Can't hurt. I'm thinking the temps out here are driving my numbers up. Dawgs should do well this year. USC isn't on our schedule so we should at least win the Pac 12. You guys should do alright despite the losses you incurred. Opening game against Kent - win, Auburn...coin toss. I'll pull for you guys.

Weak fan clutch would explain what you are seeing... Especially since your truck used to get these numbers (those are also pretty much the numbers I see on my truck, but it is essentially stock).

Goes like this: Weak fan clutch doesn't allow radiator to cool the coolant as much as it should, leaving hot coolant in the bottom tank. At that point, both the engine and trans temps will rise more than than they should.

Should be an easy fix!

-Charlie

Thanks Charlie. I think the high temps here in the NW and the old fan clutch have a lot to do with the numbers. Fan clutch on order in the AM. Those numbers that I posted from March 2016 are pretty much when it was "stock". The gears and the SC weren't installed at that time. Still ran 33's and armor. Since the gear install and the SC install, I've seen a bump in my temps but not as bad as it's recently been. I'm not going to worry about it. I'll just continually monitor them.