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Discussion Starter · #1 ·
Hey all! On a family vacation and as we got off interstate got error that Transmission Oil Temp was high. Turned off vehicle for about 20 minutes restarted and message was gone and been doing local driving with no recurrence. On interstate I was humming along at 80-85mph in 95 degree heat with a full cargo.

I need to get home and it's about 600 miles. Am I good if I keep it to a slower cruising speed? Maybe drive at night? I have a great mechanic at home that can look at it when I get back. Thoughts?
 

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I see this is your first post. Hopefully, you regularly participate in this forum so you can learn how to prevent something like this from happening again.

To help you now, try going around 70-75 max instead of 80-85mph. See if it comes back. Not knowing the weight you are carrying nor your topography, might be a good idea to drive a little slower. You might just be okay to make it home.

Later, spend some time here to know preventative and regular maintenance, like changing the transmission fluid with the exact correct spec. Not using the exact spec may bring you more problems.

I used to drive ~1500 miles round trip with my XC90 regularly. No way would I drive 80-85 consistently with full cargo and 95F heat. I also do a lot of regular and preventative maintenance so the type of issue shown in this thread doesn’t happen.

This post is a great example of why regular and preventative maintenance is important
 

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I see this is your first post. Hopefully, you regularly participate in this forum so you can learn how to prevent something like this from happening again.

To help you now, try going around 70-75 max instead of 80-85mph. See if it comes back. Not knowing the weight you are carrying nor your topography, might be a good idea to drive a little slower. You might just be okay to make it home.

Later, spend some time here to know preventative and regular maintenance, like changing the transmission fluid with the exact correct spec. Not using the exact spec may bring you more problems.

I used to drive ~1500 miles round trip with my XC90 regularly. No way would I drive 80-85 consistently with full cargo and 95F heat. I also do a lot of regular and preventative maintenance so the type of issue shown in this thread doesn’t happen.

This post is a great example of why regular and preventative maintenance is important
Yes, preventative maintenance is very important. However, I wouldn’t have an issue hauling or towing 80-85 mph in that heat in my old XC90. Towed over the weight limit in 85 degree heat around town and up massive hills and it didn’t have any issues with temp, and that’s pretty much worst case scenario since I was constantly getting that whole thing up to speed and back down again. The converter should be locked in top gear if you’re sitting on the highway so it shouldn’t be subject to huge amounts of heat. Something tells me something else is wrong. Is your converter locking up properly? Also, what do you define as a “full load”? A few bags and suitcases or a pallet and a half of bricks? Two very different ways to fill the cargo area
 
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Discussion Starter · #4 ·
Car top carrier and a full cargo area with suitcases and such for four. Nothing I really thought as overly taxing. I thought it weird as well that it was fine with no warning all along the interstate (this is I-95, so pretty darn flat) and then code popped up on slower street while pulling into a drive-thru.

On maintenence, had actually been doing well, I thought. Really wasn't aware of much needing to be done for Transmission maintenence on this. Not a hobbiest or gear head and ya know... "lifetime", lol! I'm at about 167k miles, so certainly makes sense that the fluid has reached an expiration date, but had to read here to know that.
 

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Discussion Starter · #5 ·
Oh, and not feeling any "slippage". Do get occasional clunk decelerating at low speeds. I tend to baby it and not accelerate fast or brake too fast if I can avoid it, but it's my wife's vehicle, so all bets are off when she's driving.
 

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Car top carrier and a full cargo area with suitcases and such for four. Nothing I really thought as overly taxing. I thought it weird as well that it was fine with no warning all along the interstate (this is I-95, so pretty darn flat) and then code popped up on slower street while pulling into a drive-thru.

On maintenence, had actually been doing well, I thought. Really wasn't aware of much needing to be done for Transmission maintenence on this. Not a hobbiest or gear head and ya know... "lifetime", lol! I'm at about 167k miles, so certainly makes sense that the fluid has reached an expiration date, but had to read here to know that.
Transmission fluid they say is “lifetime” - it’s not. Changing it every 60k is recommended by many, and it will help smooth out those clunky shifts.
But it still shouldn’t be overheating with a pretty normal load and normal driving conditions, even if the fluid is old.
 

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But it still shouldn’t be overheating with a pretty normal load and normal driving conditions, even if the fluid is old.
I would disagree, because at 167k miles on original fluid, not knowing how the XC90 was driven in the past, 95F weather (can make a big difference from 85F), full load, and then add extra drag with a rooftop carrier (the XC90 already doesn't have a good drag coefficient), this could certainly put enough strain on a transmission even with a locked-up torque converter. If there was nothing to indicate this would happen before the trip, then the trip is the variable. Add if there is even a slight headwind. This is not regarded as a normal load, with a normal driving condition, and as we have all learned, not normal maintenance. Anyone who has towed before knows that those 10 degrees from 85F to 95F and humidity can make a big difference in transmission temps.

Do a search and there are XC90 V8 owners who have installed a separate transmission oil cooler, separating the flow of fluid from the radiator. While this may be done so there isn't any cross-contamination due to potential internal leak, better cooling, or adding extra fluid capacity, one of the reasons why automatic transmission fluid (in almost any automatic today) flows through the radiator (even if it routes just inside the end caps) is to help the automatic transmission fluid warm up quickly to operating temp on cold days. Now use that same logic if the engine is working hard with A/C full on, on a humid 95F day, and the hot radiator could contribute to the heat of the transmission fluid. Add the transmission fluid not being changed ever at 167k miles, with the fluid broken down from use, which can also yield carbon, with friction modifiers deteriorated (for clutches), and the floating media from worn friction clutch plates.

I would recommend trying to drive at a lower highway speed and see how the vehicle responds. This would help with reducing internal friction heat and the potential for the internal clutches from slipping when trying to meet the load demand with the heat, even if slipping is not noticeable. Then when you make it home safely, do some overdue maintenance. This will also help with the baseline of your XC90 so you can evaluate those clunks.

It's simple, drive slower, do some maintenance, then reassess. Good luck with the drive and hope you and the family make it home safely. Definitely keep us updated.

Welcome to the XC90 forum!
 

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Hello from Europe country Slovenia where this days we have 38c very hot sunshine days and my transmission on xc90 2.5t AWD and cooling liquid is high... Lets say first I change ATF oil regularly every 30-40k km last 12 years and from km 1 up today in 16 years 357000 km across Europe. I have small module in OBDII and its valid all money as its control real temperature while driving on left driver display. (Swedesolutions.com) I love it for many other functionalities as closing all windows from home while start raining ect...or open to release heat inside the car on sunshine parking...

Cooling liquid was 105 C and transmission oil is 90C when I was driving in slow motion in town yesterday. As soon I came on highway - we can in EU i push kickdown to reach higher speed to cooling better 2 coolers of transmission and engine as well. And yes its helped engine cooler drop to normal 95 C and ATF to 78-80 C what is also normal. 5 speed Aisin and MObil 3309 inside. My oil is always reddish :)

Regarding the clonk - guys maybe its not transmission at all - but as I changed its first joint after bevel gear after 150.000 km need to be changed for sure. Before I had a clunk hard kick now silence.
 

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I would disagree, because at 167k miles on original fluid, not knowing how the XC90 was driven in the past, 95F weather (can make a big difference from 85F), full load, and then add extra drag with a rooftop carrier (the XC90 already doesn't have a good drag coefficient), this could certainly put enough strain on a transmission even with a locked-up torque converter. If there was nothing to indicate this would happen before the trip, then the trip is the variable. Add if there is even a slight headwind. This is not regarded as a normal load, with a normal driving condition, and as we have all learned, not normal maintenance. Anyone who has towed before knows that those 10 degrees from 85F to 95F and humidity can make a big difference in transmission temps.

Do a search and there are XC90 V8 owners who have installed a separate transmission oil cooler, separating the flow of fluid from the radiator. While this may be done so there isn't any cross-contamination due to potential internal leak, better cooling, or adding extra fluid capacity, one of the reasons why automatic transmission fluid (in almost any automatic today) flows through the radiator (even if it routes just inside the end caps) is to help the automatic transmission fluid warm up quickly to operating temp on cold days. Now use that same logic if the engine is working hard with A/C full on, on a humid 95F day, and the hot radiator could contribute to the heat of the transmission fluid. Add the transmission fluid not being changed ever at 167k miles, with the fluid broken down from use, which can also yield carbon, with friction modifiers deteriorated (for clutches), and the floating media from worn friction clutch plates.

I would recommend trying to drive at a lower highway speed and see how the vehicle responds. This would help with reducing internal friction heat and the potential for the internal clutches from slipping when trying to meet the load demand with the heat, even if slipping is not noticeable. Then when you make it home safely, do some overdue maintenance. This will also help with the baseline of your XC90 so you can evaluate those clunks.

It's simple, drive slower, do some maintenance, then reassess. Good luck with the drive and hope you and the family make it home safely. Definitely keep us updated.

Welcome to the XC90 forum!
I’m aware of the differences, I’m just using the closest point of comparison I have. If towing over the weight limit (around 5400 lbs) in 85 degrees up hills and stop and go didn’t overheat it, then just a roof box and some luggage certainly shouldn’t overheat it on the highway where the converter is locked at 95 degrees. It’s worth noting I had original 155k mile fluid in it at that point in time.

Also XC90s have seperate trans coolers as well from the factory, and I’ve towed 4600 lbs (rating is 3300) with my XC70 on an 85 degree day under the same hilly conditions and it didn’t overheat.

I’d argue that is a normal load, as it is well within Volvos set limits (gross vehicle weight, roof rack loading, etc), and even though the fluid hasn’t been changed, that’s still “normal” - Volvo doesn’t have a change interval - it’s “lifetime” fluid according to them. Yes, of course, that’s likely a contributing factor, but I and many others have put our XC90s though far more stress than that and haven’t had issues.
 

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Yup, many of us have put our XC90s through more load. That’s why it should be okay to drive home at a lower speed limit rather than the consistent 85mph. Every case is different, especially when there are higher miles, thus why a good baseline at that 167k miles should be observed after changing the transmission fluid. An XC70 has about 600-700lbs less, better aerodynamics, and not the V8 heat.

The past 3 times I changed my XC90 transmission fluid, the trans cooler line went in and out the radiator end cap (on the left driver side). It seems like a simple in and loop back out, but the line connects into the radiator and line exposed to coolant.
 

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Also XC90s have seperate trans coolers as well from the factory, and I’ve towed 4600 lbs (rating is 3300) with my XC70 on an 85 degree day under the same hilly conditions and it didn’t overheat.
Not to nitpick, but no, they don't. The only model of XC90 that came with an additional separate trans cooler from the factory was the 2.9T 6 cylinder w/ "4T65" transmission. ALL 03-14 XC90s have the integrated radiator cooler. That being said, it's very easy to retrofit the additional cooler onto any 03-14 XC90, I've done it, there are write-ups here on Swedespeed. Here's the parts diagram from the 03-05 T6 XC90 showing how the lines run:

Font Machine Parallel Art Cylinder



I have the ability to monitor temps on the dash with my CFE module (bought it because towing), and I've seen temps as high as 215F without trailer. Granted that was stop and go traffic (surprisingly in the winter time), but still, significantly higher than I was comfortable with. Ended up adding the OEM auxiliary cooler and I've generally noted 30-40F lower transmission temps all around. Towing a ~2500lbs 6x12 trailer @ 75mph in 85F weather results in more or less ~175F trans temps. Highest I've seen with the cooler is about 185F.

Can anyone actually confirm what temperature results in the high temp warning? I'd be concerned about the fluid being absolutely shot at 167k, especially with that warning. Well past time to replace it.
 

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Not to nitpick, but no, they don't. The only model of XC90 that came with an additional separate trans cooler from the factory was the 2.9T 6 cylinder w/ "4T65" transmission. ALL 03-14 XC90s have the integrated radiator cooler. That being said, it's very easy to retrofit the additional cooler onto any 03-14 XC90, I've done it, there are write-ups here on Swedespeed. Here's the parts diagram from the 03-05 T6 XC90 showing how the lines run:

View attachment 161951


I have the ability to monitor temps on the dash with my CFE module (bought it because towing), and I've seen temps as high as 215F without trailer. Granted that was stop and go traffic (surprisingly in the winter time), but still, significantly higher than I was comfortable with. Ended up adding the OEM auxiliary cooler and I've generally noted 30-40F lower transmission temps all around. Towing a ~2500lbs 6x12 trailer @ 75mph in 85F weather results in more or less ~175F trans temps. Highest I've seen with the cooler is about 185F.

Can anyone actually confirm what temperature results in the high temp warning? I'd be concerned about the fluid being absolutely shot at 167k, especially with that warning. Well past time to replace it.
Could have sworn my old XC90 had one behind the lower grill section. Guess not. Must be thinking of something else.
Good to know about adapting one to fit though
 

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Discussion Starter · #14 ·
Okay so... loving this forum already. The great journey is on Thursday, so I'll let you know how it goes. I intend to baby it home (it's actually 680 miles). Wish me luck! Having gained some understanding of how the transmission fluid is cooled by the vehicle'sgeneral cooling system (correct?), I'm thinking that it self-cooled/air cooled adequately driving at highway speed and then, when I pulled off the interstate and into the drive-thru, the temp shot up. Again, not a car expert by any stretch, but is that a reasonable guess?
 

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Okay so... loving this forum already. The great journey is on Thursday, so I'll let you know how it goes. I intend to baby it home (it's actually 680 miles). Wish me luck! Having gained some understanding of how the transmission fluid is cooled by the vehicle'sgeneral cooling system (correct?), I'm thinking that it self-cooled/air cooled adequately driving at highway speed and then, when I pulled off the interstate and into the drive-thru, the temp shot up. Again, not a car expert by any stretch, but is that a reasonable guess?
That makes sense, yeah. It’ll also unlock the converter and start shifting, which will also increase the temp.
 
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Last question before taking off tomorrow… Is turning the DSTC off easier or harder on the transmission? Thanks all!
Doesn't make a difference unless you're losing traction
 
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Glad you are home safe. Another good reason to do a trans fluid change is you can double check the fluid level in case it was running low. Recover and start planning, lol.
 

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What happened with the trans on the way back?
 
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