atalarico
Senior Member
Is there any way to tell that? I wheeled it back down and then drove down the highway to get home the next day and it didn't feel that different.
a/t fluid overheat
- Thread starter atalarico
- Start date
Is there any way to tell that? I wheeled it back down and then drove down the highway to get home the next day and it didn't feel that different.
michaeljtomey
New member
Glad I came across this! Here's my story in summary: I put new shocks and springs on my truck 2 weeks ago and now I can hold significantly more weight before I start sagging. So my buddies and I loaded the 4runner up with all our camping gear and headed up to Mammoth lakes. About 140 miles from home, I noticed smoke coming from the back of the truck. I pulled over and noticed I had sprung a leak from the A/T front bell and the bottom of my car was covered in ATF. Being in the middle of nowhere, I had to drive 40 miles backward to be within my 100 mile AAA towing range and then I towed home.
After a little more investigation and looking at it more, I was convinced that the front pump seal had either blown or cooked. I replaced my front pump seal about 20K miles ago. Last night I drove it down to my uncles shop (50 miles) and we lifted it up. We couldn't find any new leakage. Just signs of residual ATF.
So here's what I'm thinking now... a combination of hot outside heat, lots of weight and steep hills lead the ATF to overheat and pretty much boil or spray out of the pressure relief valve on the top side of the transmission. It must have been overfilled with ATF. My hopeful solution will be an external cooler and a cold air intake. I believe without an external cooler, these old trucks aren't meant to survive with extra weight and California heat. As of now, I'm just going to drive it around and see what happens.
Let me know what works for you guys and I will do the same. I hate the fact that I have no confidence in my truck right now. Its been one issue after another for the past 3 weeks.
After a little more investigation and looking at it more, I was convinced that the front pump seal had either blown or cooked. I replaced my front pump seal about 20K miles ago. Last night I drove it down to my uncles shop (50 miles) and we lifted it up. We couldn't find any new leakage. Just signs of residual ATF.
So here's what I'm thinking now... a combination of hot outside heat, lots of weight and steep hills lead the ATF to overheat and pretty much boil or spray out of the pressure relief valve on the top side of the transmission. It must have been overfilled with ATF. My hopeful solution will be an external cooler and a cold air intake. I believe without an external cooler, these old trucks aren't meant to survive with extra weight and California heat. As of now, I'm just going to drive it around and see what happens.
Let me know what works for you guys and I will do the same. I hate the fact that I have no confidence in my truck right now. Its been one issue after another for the past 3 weeks.
Roc Doc
New member
Not without a teardown, but if it starts slipping in normal operation, or temps are considerably higher in normal opertion there may have been some damage. I can't see any damage from where I sit:nod:, but you definitely need to do a full fluid swap.
As others have mentioned, a Scanguage II is your friend.
Roc Doc
New member
Why do you think it was overfilled? Did you overfill it?
All vehicles have a design envelope and it can be exceeded by operators. There was a good thread on Race Dezert about why Trophy Trucks weigh over 5000lbs, and it really starts with tire size. Want to run 40" tires at race speeds, then you'll need lots of horsepower, 800+, and super strong/heavy axle assemblies, and lots of cooling for everything that moves, and a chassis that can handle 5000lbs jumping 10 or more feet in the air, and spares, and on and on, all that stuff adds weight.
So you might have overloaded it for the conditions, and/or overfilled the transmission.
Me? I live in God's own frying pan, so I'm used to keeping an eye on the various temps of my vehicles, and willing to add additional cooling if necessary, (was on my F250 PSD, not on my EcoDiesel Ram). I'll be adding a B&M 70298 cooler soon to the Runner.
michaeljtomey
New member
Great info. Thanks! Did I overfill it? Maybe. March 2015 I bought the truck and rebuilt the engine bay and also replaced the torque converter and all seals in there. Unless I overfilled it then and never had the right conditions since to cause a problem like this then maybe.
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mtbtim
Elite Member
While you were driving, did you leave the Overdrive on? The reason why I ask is you can significantly drop your trans temp by turning off the overdrive when driving hills and mountain roads and/or loaded down with gear. It's usually around a 20 degree drop in temp when your turn the OD off. I'm guessing your trans temp probably got up there pretty high, and like you thought, maybe you were a little overfilled and it came out the breather.
An external cooler can definitely help keep the trans temps down. When I installed a B&M 70264 in-series with the radiator cooler, I experienced around a 20 degree drop in temperature. Running it in-series is a solid and proven set-up and usually the suggested way sellers of coolers will tell you how to install it.
If you think you want to bypass the radiator cooler to prevent the possibility of being a victim of the "Pink Milkshake", do ample research to figure out if this is the right set-up for you based on how you use your truck. Many are finding their bypassed set-ups aren't cutting it to keep the temps down when they are driving in situations where the truck is working hard (ie towing, 4wheeling steep trails, mountain roads loaded down with gear). Some end up adding pushing fans, a second external cooler or just a bigger single cooler to address the higher temps.
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atalarico
Senior Member
I'm really relieved (not at our misfortune) to read this because this sounds very similar to the state of my transmission over the last couple years, and I thought I was alone. Overfilled, reputable shop can't find leak, etc. Wow.
Well, my cooler comes Tuesday, and from what I've learned from the forums here's what I'm going to do:
I'm going to install it in-series, and mount it right on the condenser.
I'm doing this because my transmission has overheated in a low-speed (low airflow) high ambient temp uphill 4wd situation. Short of installing a separate fan for the aux cooler, that's the best I can do, right? My only concern is that I've read the A/C temps can suffer as a result, and I was hoping to avoid that since it gets hot here in Denver, and my A/C needs a recharge every other year or so anyway.
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mtbtim
Elite Member
My AC with the B&M 70264 cooler mounted to it seems to be working just fine but I didn't record temperatures before and after the install so I can't say for sure how much, if any, the AC has been affected. If it did affect my AC temps, I'd have to say not much because it's still blowing really cold.
You should buy some of that AC condenser cleaner you can spray onto the cooling fins and clean it up really good before you install the trans cooler. I wish I would have known about this product before I installed mine. I just blew mine out a little with some air. I think I'm going to clean it up as best I can without removing the cooler from the condenser.
Here's a link to a product [MENTION=115590]StreetCreeper[/MENTION] recommends.
AC-Safe Air Conditioner Coil Foaming Cleaner-AC-920 - The Home Depot
DK327
Member
Thanks for this, I'll pick up a can as well!
fourfive
Senior Member
I didn't have an a/c temp gauge installed when I installed my B&M 70268 bypassed a year ago but I didn't "feel" a difference in the a/c effectiveness.
This weekend I rerouted my external cooler lines to run in series because I didn't like the trans temps I was seeing after installing my scan gauge: trans>radiator>magnefine filter>external cooler>trans. Also used the a/c coil coil cleaner.
I didn't notice any felt differences in my a/c but that may have been because my condenser didn't look too dirty to begin with. Running my external cooler in series did decrease my trans temp by ~20F. My ac thermometer just came in but haven't driven with it yet.
atalarico
Senior Member
Solid recommendation! My AC condenser looks like hell anyway, so I'm definitely going to hit it with a can of this first. Thanks for saving that headache!
Innnnnteresting. Definitely makes me think I'm going the right way with doing this in-series then. I know bypassing has it's advantages for certain use cases, but I'm just not one of them I think.
Cooler comes today, and it looks like I'll be heading to home despot (har har) before installing. I'm going to pick up some extra hose while I'm there.
Just to double-check, I don't need to clamp off any of the radiator ports because I'm doing this in series, right? So, the hot ATF will come in to the radiator like normal, go out through it's port that should go back to the transmission, but then go to the external cooler, which will then send it back to the transmission?
Thanks!
mtbtim
Elite Member
That is correct. The transmission sends hot fluid to the passenger side of the radiator cooler, exits the driver side of the cooler and then you would run it to the external cooler and back to the transmission.
You might want to consider adding a Magnefine filter like many of us have done. Magnefine says to install the filter on the return line to the transmission for in-service vehicles, more than 5000 miles. The reason for this is you'll be capturing any lose particle lodged in the radiator cooler that could make their way back into the transmission. If it were a new vehicle, less than 5000 miles, you'd install the filter before the cooler to prevent lose particles from jamming up the cooler and returning to the transmission. Hope that makes sense. I installed mine between the radiator cooler and external cooler for ease of installation and mounting. I put a new radiator in and the cooler was brand new too so I could have technically mounted mine anywhere in the lines. It does have a flow direction so be careful to note that before installing.
If you are going to mount the cooler sideways, be sure to make the inlet the bottom fitting and the outlet the top fitting like B&M recommends. I don't know how important this actually is because True Cool, who have the same coolers that B&M sells, says you can mount the cooler anyway you want, even upside down, and it doesn't matter which is the inlet and which is the outlet. But, to play it safe, I'd just do what B&M recommends. I didn't know this little fact from B&M and I routed my lines with the inlet at the top and outlet on the bottom but everything seems to be fine. The reason for this is it will aid with pushing air out of the cooler if the fluid enters the bottom and exits the top.
I embedded my install video somewhere in this thread and it might help you with your install. If you have any questions, just ask.
atalarico
Senior Member
Yeah, thanks for the tips!
On the mounting position, I read somewhere in the many threads about this someone's logic that the inlet should go up top and the outlet on the bottom because heat rises, etc. I'm guessing that's not the recommendation now?
IIRC, I think the reason for being the other way is so you do not have a pocket of air trapped in the system creating a less effective cooling system. Inlet should be on bottom so it fills the cooler up to the outlet making sure there is no air trapped within. Someone mentioned the whole hot rising to the top only really matters when your talking about air, not liquid.
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mtbtim
Elite Member
My logic for having the inlet at the top and the outlet on the bottom was based on the forces of gravity and pressure. It made sense to me to have the fluid coming in from the top because gravity and the head pressure of the fluid would push the fluid downward. I wasn't even considering the issue with air being trapped in the cooler when I installed mine. It's my belief the pressure of the fluid will push any trapped air out but that's just my opinion.
Like I said, I'd just do what B&M suggests with the inlet at the bottom and the outlet on the top in a sideways installation.
I wonder if the bypass on these coolers can create a way for the fluid to pass but trap some air in the cooler? Maybe the air rises and creates a pocket. who knows, maybe it one of those things where something could happen, but the chance of it are low.
I ended up mounting mine with both pointing up because it fits better for my situation. I'm glad that I added a cooler as my temperature were getting high very quickly just using the stock radiator. I was hitting over 200 often. I run in series now. Installing a temp gauge was well worth it.
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fourfive
Senior Member
Sounds about right. I installed my cooler sideways with both ports pointing towards the driver side & it is only mounted to the a/c condenser. I did it this way when I installed it last year b/c I didn't know it was supposed to go through the ac condenser and radiator. When I rerouted my cooler lines, I was going to re-zip tie it so it goes through both condenser and radiator but after checking it out, it was very secure on the a/c condenser so left it where it was & avoid damaging any of my radiator fins.
How I routed my lines:
Trans fluid goes from trans to passenger side port on radiator > fluid exits driver side port on radiator ("L" shaped fitting) > fluid enters magnefine filter > fluid enters bottom port on external cooler > fluid exits top port on external cooler & returns to transmission.
When I had my radiator bypassed, I had my trans fluid entering the top port and exiting the bottom port on my cooler. The justification for having it enter the top port and exiting the bottom port vs entering the bottom port and exiting the top port both have reasonable justifications. Just thought I'd switch it up this time around.
idlingmike
New member
Anyone know what temperature the dash ATF temp warning illuminates?
its in the ~300F range. Give or take a couple degrees. By the time that comes on you have all but destroyed the fluid.
idlingmike
New member
So it's about as useful as the oil pressure light. Might as well make the oil pressure light the "Blown Engine" light and the ATF temp light the "Blown Trans" light.
