I noticed that the radiator cooling fan was on high speed after driving...it's quite loud when running at high speed. So today I kept a close eye on the temp gauge, and if I'm driving, especially accelerating, the gauge gets almost into the red. The fan is on high then too...but if I stop and let it idle the temps would sink back down to about the midway point, which is where they've always been. What could cause the car to only get hot while driving? The radiator and water pump must be working if the fan at idle is cooling it down. I thought maybe the radiator was blocked from airflow by a bag or something but I don't see anything. Any ideas?
Overheating when driving, but not when idling
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bureau13
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I noticed that the radiator cooling fan was on high speed after driving...it's quite loud when running at high speed. So today I kept a close eye on the temp gauge, and if I'm driving, especially accelerating, the gauge gets almost into the red. The fan is on high then too...but if I stop and let it idle the temps would sink back down to about the midway point, which is where they've always been. What could cause the car to only get hot while driving? The radiator and water pump must be working if the fan at idle is cooling it down. I thought maybe the radiator was blocked from airflow by a bag or something but I don't see anything. Any ideas?
Perhaps your radiator is clogged and therefore not able to cool effectively when there is a high demand (high engine rpm). You can get radiators flow tested.
When was the last time coolant was flushed? You might start by draining some and inspecting the contents.
When was the last time coolant was flushed? You might start by draining some and inspecting the contents.
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@bureau13 , you're maybe new to this vehicle as there are 5 motors (some with variations) over the years. Since you're showing a US flag, that'll make it 4 motors. There's not a ton of variation between them but it's hard to try and guess which one you have without even a model year.
You can either mention it in the thread title or in the initial message. Alternatively, if you use a browser for access you can set up a signature in your profile and every message you send will show everyone what you have and are likelt speaking about.
But don't tell folks quite yet, lest see if anyone guesses.
I vote 3.2-3.2 and 3.0 Thermostat failure | SwedeSpeed - Volvo Performance Forum and if it is, we'll see if @p_gill pipes up. But that's just a very uneducated guess.
Any other takers?
You can either mention it in the thread title or in the initial message. Alternatively, if you use a browser for access you can set up a signature in your profile and every message you send will show everyone what you have and are likelt speaking about.
But don't tell folks quite yet, lest see if anyone guesses.
I vote 3.2-3.2 and 3.0 Thermostat failure | SwedeSpeed - Volvo Performance Forum and if it is, we'll see if @p_gill pipes up. But that's just a very uneducated guess.
Any other takers?
I agree it's best to know which engine. What's the maintenance history, mileage, location (because of ambient temp), etc.
Could be the radiator or thermostat as mentioned. A slipping belt in higher rpms (could be due to water pump bearing issue), to it is truly running unusually hot on load. The engine type and mileage would help narrow down where to look.
Has the water pump, thermostat, and belt ever been changed?
What color is the coolant in the reservoir? (don't want to mix the wrong coolants, which can sludge up. Or if washer fluid was accidentally added to the coolant)
Does it do this only on acceleration load while moving, or does it also happen if you rev it in Park?
How is the engine power and MPG? Any change?
Does it get as hot when you gradually accelerate?
Could be the radiator or thermostat as mentioned. A slipping belt in higher rpms (could be due to water pump bearing issue), to it is truly running unusually hot on load. The engine type and mileage would help narrow down where to look.
Has the water pump, thermostat, and belt ever been changed?
What color is the coolant in the reservoir? (don't want to mix the wrong coolants, which can sludge up. Or if washer fluid was accidentally added to the coolant)
Does it do this only on acceleration load while moving, or does it also happen if you rev it in Park?
How is the engine power and MPG? Any change?
Does it get as hot when you gradually accelerate?
You're right, I don't really know the vehicle all that well yet. I will update that signature.
It's a 2005 2.5T FWD. I'm using the Peak blue coolant that I saw recommended, but I'm honestly not sure what was in it when I bought it. I did notice it was low a couple weeks ago maybe, which is why I bought that and added it. I don't see any puddles, and the plastic reservoir looked like it had coolant still (but it was hot so I should check it again). I also replaced the cap when I topped it up, thinking maybe it was bad and that's why it was low. I hadn't noticed the overheating part at that point, but I'll bet whatever is happening started back then.
I need to clarify a couple things: I haven't taken it up to highway speeds since I noticed this, it was just stop and go. The thing is, I'd stop and idle and the loud fans would cool it down to normal, but then driving (not aggressive or hard acceleration at all) between lights it would slowly heat back up. Like, the opposite of what happens with a bad fan.
I saw the note about replacing the thermostat and thought, cheap and easy, sure, why not...but everywhere I look it shows me what appears to be an entire housing for like $100. Is there really no simple thermostat l can put in that housing?
It's a 2005 2.5T FWD. I'm using the Peak blue coolant that I saw recommended, but I'm honestly not sure what was in it when I bought it. I did notice it was low a couple weeks ago maybe, which is why I bought that and added it. I don't see any puddles, and the plastic reservoir looked like it had coolant still (but it was hot so I should check it again). I also replaced the cap when I topped it up, thinking maybe it was bad and that's why it was low. I hadn't noticed the overheating part at that point, but I'll bet whatever is happening started back then.
I need to clarify a couple things: I haven't taken it up to highway speeds since I noticed this, it was just stop and go. The thing is, I'd stop and idle and the loud fans would cool it down to normal, but then driving (not aggressive or hard acceleration at all) between lights it would slowly heat back up. Like, the opposite of what happens with a bad fan.
I saw the note about replacing the thermostat and thought, cheap and easy, sure, why not...but everywhere I look it shows me what appears to be an entire housing for like $100. Is there really no simple thermostat l can put in that housing?
Update...it turns out I cannot see the coolant level as accurately as I thought. The expansion tank was empty. I put 2/3-3/4 of a gallon in there before it was up to the middle of the tank and stayed there. Poking around further, the lower coolant hose has an oily residue all over it. I suspect coolant has been seeping out of there, it gets low and then overheats. It must be fairly slow, and only when pressurized. Not sure why it's so oily, the coolant and oil both look fine (i.e. I don't think I'm mixing them internally aka head gasket hell). I will see if it stays within operating temps tomorrow, meanwhile I'm ordering a new hose.
...and I'm dumb, that's not a radiator hose, that's a boost pipe, and I apparently need to replace the rubber ends. The oily residue is oily because it's oil 
. So, I still don't know where my leak is, but I've got on somewhere. My luck, it'll be the radiator itself, or worse.
. So, I still don't know where my leak is, but I've got on somewhere. My luck, it'll be the radiator itself, or worse.The inter cooler pipe for the turbo does get oily on these cars, it’s totally normal. If you intend to keep this vehicle for a while, you’ll want to check the health of the PCV system —do a search for “PCV glove test” and that’ll get you started....and I'm dumb, that's not a radiator hose, that's a boost pipe, and I apparently need to replace the rubber ends. The oily residue is oily because it's oil
Sounds like you could be lucky with the low coolant fixing your immediate problem. Ideally you’d want to identify why you are loosing coolant, 2/3 gallon is quite a lot. After you start it and let it idle, check for leaks.
Also, these cars have a coolant level sensor that trips, I’m curious if you had any dash messages? Mine trips as soon as coolant is about 1 quart low.
The blue Peak is okay to use as long as it says for Euro. Since there is a belly pan under the engine, it can sometimes be difficult to see coolant leaks. With the 2.5t, look around the thermostat housing for clues of the gasket leaking. It can be temperamental with the gasket, meaning, not consistent and difficult to see because it may drip under the intake manifold area. Sometimes you can only see clues if you use a phone to reach in and take pics under the manifold or if you are under the vehicle. Also, look inside the timing belt cover or the passenger side lower subframe for clues of coolant leaking. This could indicate it's from your water pump and perhaps in higher volumes from rpms or pressure, coolant is leaking out.
The thermostat is inside the housing, but it can be difficult to remove the old thermostat without removing the upper part of the thermostat housing. For removal and install, you can remove the power steering pump, to help gain access to the lower bolt, but a wobble extension can help the access without p/s pump removal. There's a lot of documentation on the forums on this. You can watch YouTube videos too.
I have only done the entire thermostat housing and gasket. I also purchased new screws/bolts in case I messed up the torx on removing the old ones, especially that lower one.
Sad to say. If you don't know the maintenance history of your XC90 and a $100 thermostat is too much for your budget, then this XC90 could get costly for you if the maintenance has not been done.
The thermostat is inside the housing, but it can be difficult to remove the old thermostat without removing the upper part of the thermostat housing. For removal and install, you can remove the power steering pump, to help gain access to the lower bolt, but a wobble extension can help the access without p/s pump removal. There's a lot of documentation on the forums on this. You can watch YouTube videos too.
I have only done the entire thermostat housing and gasket. I also purchased new screws/bolts in case I messed up the torx on removing the old ones, especially that lower one.
Sad to say. If you don't know the maintenance history of your XC90 and a $100 thermostat is too much for your budget, then this XC90 could get costly for you if the maintenance has not been done.
NorthwestDriver, I have no warning messages about coolant level. I was just going to ask about that...sounds like I need to replace the level sensor.
ChitownV, I understand what you're saying. If I had any solid evidence that the thermostat or housing were bad, I'd have already ordered one. I guess I would state it that it's not too much to pay to fix it, but it's too much to pay just to throw parts at it. I've been down that road before on other cars, and it never ends well! The advice on looking for leaks is helpful, I will try those things.
ChitownV, I understand what you're saying. If I had any solid evidence that the thermostat or housing were bad, I'd have already ordered one. I guess I would state it that it's not too much to pay to fix it, but it's too much to pay just to throw parts at it. I've been down that road before on other cars, and it never ends well! The advice on looking for leaks is helpful, I will try those things.
If it's overheating when you start to drive but it was ok at idle I would look at the water pump. It sounds like the coolant isn't circulating properly when your driving, the water pump is responsible for moving that coolant quickly once those RPM's get going on the road.
One reason to focus on the cooling system, besides that's where you have a current issue, is it can give clues about the maintenance history. If the water pump is bad, is weeping from the weep hole, or leaking from its gasket, this could indicate the timing belt was never changed. You did not state your mileage and knowing that would help. If you have to do a timing belt service (belt, water pump, tensioner, and a good time to do the serpentine belt service), then it's also a good time to do the thermostat and coolant hoses due to wear/age. Another indicator if the timing belt was never done is the thermostat gasket leak and the condition/color of the thermostat housing (you can also try to locate the brand if it is a cheaper replacement aftermarket one). For the timing belt, if there isn't a timing belt service sticker on the plastic engine cover, then you can also look at the belt and even stick your phone down to take pics of the water pump and tensioner for clues.
If you have a cooling issue, throwing money into the coolant system is not just throwing money. It's fixing the coolant system especially if you don't know the history. This is a problem, as you have shown, that can leave your vehicle sitting to prevent damage in normal driving.
Hopefully, it is a simple thing like a cheap aftermarket thermostat assembly with a bad temp sensor or a bad thermostat. Good luck with the diagnosis.
I did not see it mentioned here or I missed it,
FYI, Do not use straight coolant, mix it 50/50 with water.
Straight coolant is thicker like syrup.
The eng will overheat because the thicker syrup coolant cannot get rid of the heat fast enough
going across the radiator.
FYI, Do not use straight coolant, mix it 50/50 with water.
Straight coolant is thicker like syrup.
The eng will overheat because the thicker syrup coolant cannot get rid of the heat fast enough
going across the radiator.
The coolant I'm using is premixed 50/50. Now, just for topping it up as I look for the leak, I'm using distilled water. I know that's not ideal but it's not going to be in there too long.
The vehicle was actually pretty well-maintained. The timing belt was done a bit over 100K, and it currently has 186K. So it's not overdue, but it's not that far off.
When I got it, it had the following problems:
- Service Alarm message, i.e. alarm battery crapped out and sunroof doesn't open, which is weird, but as I understand it, commonly related.
- (Drawing a blank on the name) the anti-skid thing not working message, which supposedly is either the steering angle sensor or some other device under the passenger seat
- 2 OBD2 engine codes related to some evaporative emissions thing, according to PO it is most likely one of two things but he wasn't sure how to tell which.
Other than that, good condition for its age. Since then I've developed a noisy wheel bearing (hub should be here soon) and a bad rear Nivomat shock, which I replaced. I'm still hearing a noise from the rear suspension which I thought the shock would fix, so something else going on back there.
The vehicle was actually pretty well-maintained. The timing belt was done a bit over 100K, and it currently has 186K. So it's not overdue, but it's not that far off.
When I got it, it had the following problems:
- Service Alarm message, i.e. alarm battery crapped out and sunroof doesn't open, which is weird, but as I understand it, commonly related.
- (Drawing a blank on the name) the anti-skid thing not working message, which supposedly is either the steering angle sensor or some other device under the passenger seat
- 2 OBD2 engine codes related to some evaporative emissions thing, according to PO it is most likely one of two things but he wasn't sure how to tell which.
Other than that, good condition for its age. Since then I've developed a noisy wheel bearing (hub should be here soon) and a bad rear Nivomat shock, which I replaced. I'm still hearing a noise from the rear suspension which I thought the shock would fix, so something else going on back there.
It doesn't look obviously newer than the rest of the engine compartment. If I were to hazard a guess, I'd guess that it has not been replaced.
So, it goes back to what was suggested by others. This forum has many many experienced people in the 2.5t's. Check for leaks and perhaps change the thermostat. Hopefully, it is as simple as that, but it appears the thermostat assembly and gasket will need to be changed just based on age.
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