Try thermostat first. It should be quite easy. Water pump is quite hard usually.

 

Isn't it still under warranty?
If so, just take it to the dealer. I'm sure they'll have you on the road in no time.

If not, all the best to you my friend.

 

Isn't it still under warranty?
If so, just take it to the dealer. I'm sure they'll have you on the road in no time.

If not, all the best to you my friend.

Would guess it depends on when he bought car. 4 yrs / 50K is standard. So chances it may be out of warranty are significant, although if it's dealer serviced, he may be able to appeal for some good will if the problem is truly substantial in nature.

 

This is really a cause for concern, a temperature over 90 degrees Celsius (195 Fahrenheit) is bad.
Hope it's a thermostat or some electrical problem But I still suspect the water pump, because the oscillations in temperature are really big in a short period of time

 

This is really a cause for concern, a temperature over 90 degrees Celsius (195 Fahrenheit) is bad.
Hope it's a thermostat or some electrical problem But I still suspect the water pump, because the oscillations in temperature are really big in a short period of time

I assume the X-axis is seconds. So yes, we're seeing an almost instantaneous temperature rise of 60+F, which does not seem physically possible. It could be some sort of steam bubble flowing across the sensor, but I think it's more likely to be an electrical issue.

Zoom in on one of the spikes and check the connectors and wiring. Surprised it didn't throw a sensor code, though.

 

Did you check for any codes?
Remove the engine cover and inspect all of the engine bay area wiring for wire damage or mouse chewing.
The 2016,2017 possibly 2018 4-cylinder engines had an issue with the t-stat temp sensor shorting out.
It should set a hard code and a message; it was not uncommon to just set a soft code and no message.
If the t-stat assembly was not replaced, over time the t-stat short would burn out the t-stat circuit inside the ECM.
If the temp sensor code is permanent, will not erase, the ECM will need to be replaced.
The ECM is covered under the 8/80 warranty.
The t-stat assembly includes a new temp sensor.
You may not have the t-stat code or soft code but it is something to look into.

 

More false info. A "permanent" code is one that doesn't clear itself after a specific number of start/drive cycles and has to be manually cleared. Which is 99% of DTC's. The only truly permanent codes that cannot be reset are codes for memory errors and driver errors in the ECM

 

Anytime I see massive coolant temperature fluctuations, I would look at actual coolant level first. Then I would check circulation (pump/hoses (clog/collapsing under flow).

 

A t-stat failure is usually presents as no heat in the cabin. given the chart presented I would guess fan issue or maybe debris blocking the radiator cooling fins. Unless.... those spikes are only a few seconds - then I'd guess you don't have any issue at all. Likely just normal sensor fluctuation. See if the OBDB port can provide "head temp" this will be more telling.

 

Only if the thermostat fails open. Most of the time they fail closed so the vehicle will overheat, but it won't spike temperatures as rapidly as the OP's data graph shows. Even a bad water pump won't spike up and down as fast as the OP's graph.
I would check the wiring harness to make sure the temp sensor connector pins didn't get pushed back out of the connector, wires aren't cracked/split and shorting against the frame/engine somewhere. Hook up the scan tool with key on, engine off, and watch it while you wiggle the connector and wires and work your way backwards into the main harness

 

If you're seeing 60+ degree swings in a tenth of a second, it's not real. Need to zoom in on one of the spikes.

 

OP, 1 post and done, not worth debating until they come back.

 

In Volvo's Drive-E 4cyl direct injection engines (the T6 is all-aluminum, turbocharged and direct-injected), when refilling the coolant, it is highly advised to use a vacuum coolant bleed tool instead of conventional filling to avoid air bubbles. When you replaced that sensor, maybe did you accidentally allow air into the cooling system? Did you use a vacuum coolant bleed tool to get rid of said air?

The pattern you show, if the sensor is OK, then it indicates rapid heating and cooling. Various things can cause that. For instance, you can have 'cavitation,' which is when the liquid that's supposed to flow in a pump turns to a vapor at low pressure, and occurs because there is not enough pressure at the suction end of the pump. An air bubble big enough to let the impeller of the pump spin in gas (coolant vapor, air, etc) rather than moving liquid coolant would do just that. Jostle things a bit so that the pump can pull liquid and then things (your cooling system) cools the sensor off again until the gas bubble cavitates the pump again... and again... and again. Or it could be there is an electrical problem at the senor or its wiring - the speed of the fluctuations hints that such might be the case - however, if so then I'd expect the temperature shown to hit some certain asymptote; the peaks or the valleys would all be about the same, and the frequency would be more or less in alignment with the make-and-break of electrical contact. I don't know for sure, I have not worked on your car, but that's what I'd expect.

This being the case, without the vacuum coolant bleed tool, more replacements may not fix much. If you're not familiar with this tool already, no worries. You should be able to buy or borrow one locally at an auto parts store, and here's a link to an Amazon page listing a bunch of them: Amazon.com : coolant vacuum refill kit. On some such engines I understand there are workarounds for not using such a vac tool (actually you need "shop" compressed air to run it) but I'm not familiar with those workarounds either.

What say you?

 

In Volvo's Drive-E 4cyl direct injection engines (the T6 is all-aluminum, turbocharged and direct-injected), when refilling the coolant, it is highly advised to use a vacuum coolant bleed tool instead of conventional filling to avoid air bubbles. When you replaced that sensor, maybe did you accidentally allow air into the cooling system? Did you use a vacuum coolant bleed tool to get rid of said air?

The pattern you show, if the sensor is OK, then it indicates rapid heating and cooling. Various things can cause that. For instance, you can have 'cavitation,' which is when the liquid that's supposed to flow in a pump turns to a vapor at low pressure, and occurs because there is not enough pressure at the suction end of the pump. An air bubble big enough to let the impeller of the pump spin in gas (coolant vapor, air, etc) rather than moving liquid coolant would do just that. Jostle things a bit so that the pump can pull liquid and then things (your cooling system) cools the sensor off again until the gas bubble cavitates the pump again... and again... and again. Or it could be there is an electrical problem at the senor or its wiring - the speed of the fluctuations hints that such might be the case - however, if so then I'd expect the temperature shown to hit some certain asymptote; the peaks or the valleys would all be about the same, and the frequency would be more or less in alignment with the make-and-break of electrical contact. I don't know for sure, I have not worked on your car, but that's what I'd expect.

This being the case, without the vacuum coolant bleed tool, more replacements may not fix much. If you're not familiar with this tool already, no worries. You should be able to buy or borrow one locally at an auto parts store, and here's a link to an Amazon page listing a bunch of them: Amazon.com : coolant vacuum refill kit. On some such engines I understand there are workarounds for not using such a vac tool (actually you need "shop" compressed air to run it) but I'm not familiar with those workarounds either.

What say you?

Basically, they are the same two aluminum engines, with the same volume, the only difference is that one model has a turbocharger and the other model has a turbocharger and supercharger.

Volvo doesn't mention use a vacuum coolant bleed tool anywhere

XC60 Topping up coolant | Volvo Support EN-TH

Volvo Support for XC60 Topping up coolant | The coolant cools the internal combustion engine to the correct operating temperature. The heat that is transferred from the engine to the coolant can be used to heat the passenger compartment.

www.volvocars.com

If you have a relevant source of information for that, please link

 

There is a problem with older models that was solved by adding
Bleeder Hose between the cooling system radiator and the cooling system expansion tank which will evacuate the trapped air

Vehicle Recall Number R/2020/210

Details of the vehicle recall #R/2020/210 issued by VOLVO CAR

dot.report

 

FWIW, I'm unaware of any modern engine that does NOT require a vacuum filling tool. And yeah, I do think it's possible to fix one problem and induce another.

If you perform a repair on any modern vehicle's cooling system, you have to replace the coolant and purge the air from the system. I have not seen the factory service manual for this car, but I given what I know out the head/block and cooling system, I would be shocked if this is not a requirement for doing a coolant replacement, OR after a repair where the cooling system is opened.

 

FWIW, I'm unaware of any modern engine that does NOT require a vacuum filling tool. And yeah, I do think it's possible to fix one problem and induce another.

If you perform a repair on any modern vehicle's cooling system, you have to replace the coolant and purge the air from the system. I have not seen the factory service manual for this car, but I given what I know out the head/block and cooling system, I would be shocked if this is not a requirement for doing a coolant replacement, OR after a repair where the cooling system is opened.

+1 to that. Vac filling tools eliminate uncertainty after opening a cooling system.

The other thing I notice is that the OP (Conorxc) has "left the building" and unless/until OP provides an update, I'm done here.

Albertj