Hello all,
I have a 2008 s40 t5 and this was the case last year too... I would like to say its the thermostat? When the outside temperature got bellow 40 degrees this week I noticed my car will start to cool down past operating temp at an idle or light cruising speed. Of course, it will heat back up when acceleration is used. Has anyone had this problem and was a different problem? at 40 degrees this happens... Not like its -30 lol

 

That's got to be a thermostat. And worse, if it's not helping the engine come up to temperature properly, you'll be getting fewer miles on each gallon of gas when the engine management computer is defaulting to its conservative "warm-up values" for fuel injection. Modern engines are designed to run at a specific temperature (usually pretty close to 200° F) and if they're not, they're just not going to be at 100%.

 

I'd also check the resistance of the ECT at cold and hot temps - there's resistance tables online. If you're going to swap out the thermostat, you should consider replacing the ECT as well since its right there.

 

I'll add that you should be happy you're doing the thermostat on a Volvo. I just did my Audi A3, and it requires removing turbo hoses, the alternator, and a host of "little stuff" - normally about a 3-4 hour job (things like that are the reason most of us hate automotive engineers). ;-)

 

yep, when your biggest worry is what size torx bit, you got it good!

 

Thanks guys,
Lol I think a thermo on a honda pilot is easier... this thing and its airbox..... Really makes me want to go aftermarket and get rid of that box lol.