a/t fluid overheat

[atalarico]

Hey all,

First time this has happened in the 6 years of owning my 97 Limited. I was wheeling up a pretty steady and steep 3 or 4 mile trail (lower Crystal Lake in Colorado) and about 3/4 of the way there, I got the a/t oil light indicating that my transmission was overheating. While it wasn't slipping per say, it certainly wasn't delivering power the same way either. Something also definitely smelled like burning oil, but it could have been ATF. That being said, it normally smells like that since I never cleaned my engine bay of the built up oil leak after changing my valve cover seals.

I stopped my truck as soon as I found a flat spot and let it sit for 10 minutes. Started her up again, and when I was a few hundred feet away from where I was going it came on again.

Now, I'm guessing this had to do with a few things but I just want to makes sure I'm not missing anything:

1.) It was hot out, and I had just put a pretty hard highway drive on her to get to the trail to begin with, with barely any rest.

2.) I just replaced the transmission pan and it's possibly I put too much ATF in. I'm going to check tonight and siphon some out if needed (I have an oil extractor for my other car that I can top-side change with). I've heard too much can cause overheating too.

3.) I replaced the original rad with a Denso late last summer. The coolant was halfway between F and the L in the overflow reservoir. I didn't think that would be a big deal, but maybe? Also, it's strange because the last time I checked that (a couple weeks ago) it was closer to F. I figured since I changed my rad anyway, and I don't tow or wheel that hard, I don't need an external tranny cooler. However, I am going to check for milkshake later today just in case.

The drive home was totally fine. I had it in 4lo and 2nd and L for most of the descent, and it didn't overheat again. I stopped to air back up and let it sit for 15 minutes.

Thoughts?

 

[4racer]

Fact of the matter is the stock cooler isnt able to handle that long grade without the TC locking up. If you were in 4WD or 4Lo, it makes the problem even worse. For the light to come on, your tran oil temp has to hit about ~300F. So its was cooked pretty good. In the 10 minutes you let it sit, since it was off, you weren't cooling the fluid. You need to leave it on so the fluid has a chance to circulate and cool down. Hence why when you started it up again, the light came back on in no time.

You should installed a trans cooler in series to help keep your temps down. A 70264 should be good to install in series. If you want even bigger try a 4589 in series with the radiator. If you decide to bypass, you will need to install a fan.

 

[gamefreakgc]

I echo the last statement. You my friend are a great candidate for a cooler. Since you've replaced your radiator, I (and the cooler manufacturer) recommend installing it in series with the radiator per the installation instructions.

 

[atalarico]

Well...dang. I appreciate the advice! Any ideas as to why I've never had that light come on in the 6 years of similar use? Just luck? Maybe fluid level too?

Today is turning out to be an expensive day since I've added a 199mm Tundra Brake upgrade to my ever growing list of upgrades for the Runner. Le sigh. It's cheaper than a tranny though!

Edited to add: and since I just replaced the radiator, and was sure to splurge on the SLLF Coolant...does that mean I have to sadly watch that money go down the drain, or can I recapture it and reuse it?

 

[4racer]

Well...dang. I appreciate the advice! Any ideas as to why I've never had that light come on in the 6 years of similar use? Just luck? Maybe fluid level too?

Today is turning out to be an expensive day since I've added a 199mm Tundra Brake upgrade to my ever growing list of upgrades for the Runner. Le sigh. It's cheaper than a tranny though!

Edited to add: and since I just replaced the radiator, and was sure to splurge on the SLLF Coolant...does that mean I have to sadly watch that money go down the drain, or can I recapture it and reuse it?

Luck, weather, hill, speed of ascent. Could really be a number of factors that caused it to go off. Check your fluid level, but unless extremely low, probably not an issue.

You should flush or do a drain and fill on the fluid. Since it has been over 300F and is not synthetic (im assuming). Switching over to synthetic also gives you more head room on fluid temp. Though 300F is never good.

Lastly, your cooler and radiator do not share any fluid, so you shouldn't have to even touch the coolant in regards to installing a cooler. I have a I just pulled out of my 4runner. In like new condition if you want it for 35 shipped.

 

[gamefreakgc]

Well...dang. I appreciate the advice! Any ideas as to why I've never had that light come on in the 6 years of similar use? Just luck? Maybe fluid level too?

Today is turning out to be an expensive day since I've added a 199mm Tundra Brake upgrade to my ever growing list of upgrades for the Runner. Le sigh. It's cheaper than a tranny though!

Edited to add: and since I just replaced the radiator, and was sure to splurge on the SLLF Coolant...does that mean I have to sadly watch that money go down the drain, or can I recapture it and reuse it?

The radiator doesn't have to go anywhere for installation, just maybe the fan and shroud depending on how you install it. I used the zip-tie method in front of the radiator and A/C condensor which is very easy and secure. No coolant needs to be drained at all. You might want to look into replacing your transmission fluid though depending on how bad it burnt.

 

[steezemcqueen]

While you were wheeling prior to the light coming on, was it in 4Lo?

 

[atalarico]

Luck, weather, hill, speed of ascent. Could really be a number of factors that caused it to go off. Check your fluid level, but unless extremely low, probably not an issue.

You should flush or do a drain and fill on the fluid. Since it has been over 300F and is not synthetic (im assuming). Switching over to synthetic also gives you more head room on fluid temp. Though 300F is never good.

Lastly, your cooler and radiator do not share any fluid, so you shouldn't have to even touch the coolant in regards to installing a cooler. I have a I just pulled out of my 4runner. In like new condition if you want it for 35 shipped.

I just refilled it with maybe 7 quarts of last week after I replaced the transmission pan and gasket. It had been draining for a couple weeks, so it was a lot more than the usual 3-4 quarts, which I started with but then kept having to add and add until the dipstick registered the right amount (yes, I know the correct way to check the ATF too).

Do I really need to replace it all? I'm not trying to be cheap, but the amount of work I've had to put into this truck in the last 6 months is getting excessive for on occasional weekend truck. I'm having a hard time believing that I've ruined all of the fluid in there if it was a one-time occurrence with brand new fluid, and the next time it gets driven it will have a transmission cooler. Like I said, literally never had this light come on before in identical and worse conditions (which is what made me think I've simply overfilled the ATF a bit).

 

[atalarico]

While you were wheeling prior to the light coming on, was it in 4Lo?

Yes. Also, hey, nice to see you! I think you helped me out with replacing my 5100s last summer over at Toytec, and I follow you in insta (I'm @lonememe).

Why do you ask?

 

[4racer]

I just refilled it with maybe 7 quarts of last week after I replaced the transmission pan and gasket. It had been draining for a couple weeks, so it was a lot more than the usual 3-4 quarts, which I started with but then kept having to add and add until the dipstick registered the right amount (yes, I know the correct way to check the ATF too).

Do I really need to replace it all? I'm not trying to be cheap, but the amount of work I've had to put into this truck in the last 6 months is getting excessive for on occasional weekend truck. I'm having a hard time believing that I've ruined all of the fluid in there if it was a one-time occurrence with brand new fluid, and the next time it gets driven it will have a transmission cooler. Like I said, literally never had this light come on before in identical and worse conditions (which is what made me think I've simply overfilled the ATF a bit).

Your truck, your call. Just telling you what is recommended. Heat is what kills Trans fluid.

 

[atalarico]

The radiator doesn't have to go anywhere for installation, just maybe the fan and shroud depending on how you install it. I used the zip-tie method in front of the radiator and A/C condensor which is very easy and secure. No coolant needs to be drained at all. You might want to look into replacing your transmission fluid though depending on how bad it burnt.

Good to hear then. How does one determine how badly it burnt? Smell?

 

[steezemcqueen]

Yes. Also, hey, nice to see you! I think you helped me out with replacing my 5100s last summer over at Toytec, and I follow you in insta (I'm @lonememe).

Why do you ask?

:thumb3:

If you were in high range, the trans is going to work alot harder which is going to cause the fluid to get hot quick.

I would say a external trans cooler is in your future

 

[atalarico]

:thumb3:

If you were in high range, the trans is going to work alot harder which is going to cause the fluid to get hot quick.

I would say a external trans cooler is in your future

Ah, but I was only in 4lo for maybe 10% of the time, so does that still fit your theory? I was in 4lo when it came on during the steepest part of the ascent, but I tend to switch out of 4lo as soon as I don't need it.

 

[atalarico]

Your truck, your call. Just telling you what is recommended. Heat is what kills Trans fluid.

I'm not trying to argue, and I very much appreciate your input, I'm just frustrated and a bit demoralized now. I've spent so much time and money on maintenance in the last 6 months and it just isn't letting up at all. I love my truck, but it's really ****ing testing my love right now.

What I'm seeing on this chart is that I was over 300F for about .2 miles. This chart is showing averages...which means I wasn't at an average of 300F if I only hit that once in 231k miles. I'm guessing if it smells burnt though, I should toss it if I want this tranny to go another 231k?

If I do another round of drain refills, and if I have some basic Castrol Dex/Merc in there right now (this), can I start draining and refilling with this and be OK (link)

 

[DK327]

At minimum do an ATF fluid drain and refill which will replace 4QT's out of 12QT's and should hold you over until you can flush it completely... Like others said get an external cooler and mount flush against the condenser or get one with a fan and mount it anywhere you want. Might also want to invest in a scangauge or some type of sensor to monitor trans/engine temps, going forward. Relying on factory gauges can be a huge mistake.

 

[4racer]

I'm not trying to argue, and I very much appreciate your input, I'm just frustrated and a bit demoralized now. I've spent so much time and money on maintenance in the last 6 months and it just isn't letting up at all. I love my truck, but it's really ****ing testing my love right now.

What I'm seeing on this chart is that I was over 300F for about .2 miles. This chart is showing averages...which means I wasn't at an average of 300F if I only hit that once in 231k miles. I'm guessing if it smells burnt though, I should toss it if I want this tranny to go another 231k?

If I do another round of drain refills, and if I have some basic Castrol Dex/Merc in there right now (this), can I start draining and refilling with this and be OK (link)

If it still smells sweet then you should be okay. Keep an eye on it. If you feel any slipping or other issues then fluid could be an issue. No arguing, just trying to help you and make sure your truck won't need a Trans down the line.

It can be disheartening when it comes to the maintainance, but they do run a while and I think what happens if everything happens at once. So instead of 50-60 here and there. It's 300-400 at once, which can be hard.

 

[atalarico]

If it still smells sweet then you should be okay. Keep an eye on it. If you feel any slipping or other issues then fluid could be an issue. No arguing, just trying to help you and make sure your truck won't need a Trans down the line.

It can be disheartening when it comes to the maintainance, but they do run a while and I think what happens if everything happens at once. So instead of 50-60 here and there. It's 300-400 at once, which can be hard.

Alright, I'll take a whiff then. I'm betting that burning smell was coming from the trans then instead of the usual leftover oil spill mess (and don't get me started about how that seems to be coming back now even though I did my VC gaskets last summer). I appreciate the help!

That's basically how I'm feeling about the maintenance too. Some of this is deferred since it was my daily for 6 years, and the last year of that was rough on her. I just need to reprioritize the maintenance tasks now:

1.) This takes first place, since replacing a trans is going to be the worst outcome. I've never flushed the trans and it has 231k on it. Everything I understand about flushing at that age just sounds like I'd be inviting failure, you know? I think the drain/refill will be how I attack this.

What did you say you had for $35 shipped? A cooler?

2.) Tundra brakes down to second. I can get by on the brakes I have, for another month or two (and put more of the braking on the transmission a bit more since it'll be cooler and happier).

3.) ITR's and OTRE's going down to third since they're not in the worst shape.

4.) Rear transfer case output shaft seal

5.) U-joints

And on and on.

Sigh.

 

[4racer]

Alright, I'll take a whiff then. I'm betting that burning smell was coming from the trans then instead of the usual leftover oil spill mess (and don't get me started about how that seems to be coming back now even though I did my VC gaskets last summer). I appreciate the help!

That's basically how I'm feeling about the maintenance too. Some of this is deferred since it was my daily for 6 years, and the last year of that was rough on her. I just need to reprioritize the maintenance tasks now:

1.) This takes first place, since replacing a trans is going to be the worst outcome. I've never flushed the trans and it has 231k on it. Everything I understand about flushing at that age just sounds like I'd be inviting failure, you know? I think the drain/refill will be how I attack this.

What did you say you had for $35 shipped? A cooler?

2.) Tundra brakes down to second. I can get by on the brakes I have, for another month or two (and put more of the braking on the transmission a bit more since it'll be cooler and happier).

3.) ITR's and OTRE's going down to third since they're not in the worst shape.

4.) Rear transfer case output shaft seal

5.) U-joints

And on and on.

Sigh.

Have you checked the half moons on the back of the valve covers? Usually they are the first culprit if you already did you VC.

Putting off maintenance happens. But once you're done with this, you'll be good other than oil changes. So look at it as a long term investment.

A good drain and fill will just make sure you have some fresh fluid and will be about 4-5 quarts in total. Just more of a precaution than anything else.

I do have an B&M I ran for about 6 months. Still in good condition I would sell you for 35.

Whats wrong with your U joints?

 

[atalarico]

Have you checked the half moons on the back of the valve covers? Usually they are the first culprit if you already did you VC.

Putting off maintenance happens. But once you're done with this, you'll be good other than oil changes. So look at it as a long term investment.

A good drain and fill will just make sure you have some fresh fluid and will be about 4-5 quarts in total. Just more of a precaution than anything else.

I do have an B&M I ran for about 6 months. Still in good condition I would sell you for 35.

Whats wrong with your U joints?

Yeah, I actually did the VC job twice because I didn't receive cam shaft seals the first time. Both times I removed the half moons and resealed them with FIPG, but I'm honestly going to take it to a shop for them to diagnose the oil smell. I'm mixed about telling them the VC gaskets were done recently, since it would be telling if they said something like the VC gaskets are original and worn out. Yee haw.

Yeah, I think you're right about the "past this it'll just be oil changes for a while again", but I've been holding out for that point for a while, and I'm wondering if that's a pipe-dream since it has 231k on it. I'll keep trying though since I really do love this truck.

PM me about the cooler, but yes, I'm in on that for sure so long as this isn't a part I'd need to be replacing every 6 months!

U joints are just original and I was going to replace them to rule out some sloppy drivetrain feels I have.

 

[StreetCreeper]

At minimum do an ATF fluid drain and refill which will replace 4QT's out of 12QT's and should hold you over until you can flush it completely... Like others said get an external cooler and mount flush against the condenser or get one with a fan and mount it anywhere you want. Might also want to invest in a scangauge or some type of sensor to monitor trans/engine temps, going forward. Relying on factory gauges can be a huge mistake.

I agree completely about the ScanGauge. Even though Atalarico can't monitor his tranny temps with a ScanGauge, he can still monitor engine coolant temp which gives great insight to how the rest of the truck might be doing.

If not for my ScanGauge, I would never have known that my coolant temps were climbing towards dangerous territory since the factory gauges are next to useless and never showed any temp change at all.

I'll never own an OBD2 equipped vehicle again that is not outfitted with a ScanGauge or similar reader. The real-time data is absolutely invaluable if you want to be alerted to problems — before they even become problems.

In my case, the higher temps were a result of a failing fan clutch. Interestingly, the fan clutch passed all the typical test for determining whether the clutch is good or bad. In every respect the fan clutch seemed fine, yet replacing just the clutch fixed the higher temps immediately.

I credit the ScanGauge with saving me a lot of potential future damage from repeated and succeedingly higher coolant temps before finally being alerted by the dash light or other overheating symptoms.

Perhaps Atalarico has a failing cooling system that simply hasn't registered yet on the useless factory gauges — contributing to his high tranny temps? Something to consider anyways.