Volvo cooling system troubleshooting
 

Hi everyone.

My 04 s60R strikes again. Got stranded on the highway because the coolant temp was pegged. I need some mt.net brainpower since the volvo guys aren't really thinkers.

Back story:

Start my car for work. Scrape the ice off the windows. Get on the highway and the coolant temp is at the halfway mark just where it always is. My heat isn't working. At all. I just figured in the s60's they added a valve to bypass the heater core (the 850's heater core always has hot coolant flowing). So I'm thinking, 'I'll fix it later'. I keep checking the water temp every 30 seconds or so. I forget to for about a minute and I see that the needle is pegged. I pull over right as I get a message that the engine is overheating and to pull over. I open the hood and the overflow tank is bubbling over.

So I wait awhile (in 14 degree weather with no heat) and I keep switching the key on engine off. The water temp gauge doesn't move, so I assume it doesn't work unless the car is on (dumb). Finally after thirty or so minutes I limp it to a mall parking lot on the next exit. My friend brings me some distilled water that was in his garage so it was icy. The overflow tank at that point is empty so I open it up (no hissing sounds or signs of pressure) and then I fill up the overflow tank. The car was fine on the 5 mile trip home and the heat worked again.

The first thing I thought was the freeze plug in the block popped out last night. But there was no coolant in my driveway and there wasn't any noticeable puddles where I left the car for over an hour.

So I went to the dealer and got some coolant and bought some prestone super flush and I'm going to try flushing the system hoping something got clogged.

I have records of a volvo dealer doing a compression check about a year ago and it looked good. So I am doubtful that it's a head gasket. I haven't found oil in the coolant or coolant in the oil.

I haven't messed with the cooling system yet, but I couldn't find any leaks when it was hot and I have not had to add any coolant since I bought it in September. At 155k miles, I assume the radiator (aluminum with plastic endtanks) is the same one from the show room floor and they are known to crack.

Any thoughts/ideas? Methods of troubleshooting wtf happened (without buying a radiator pressure tester kit)?

edit: turbo is water cooled and was rebuilt less than 20k miles ago.

Coolant leaks under pressure only or you would have seen the leak in your driveway..... you lost coolant and whatever was left wasn't hot enough and boiled over.

Pressurize your rad and go searching.

I'd check the radiator first. I had just about this same exact situation happen to me about a month ago. Had my fancy PWR aluminum radiator tanked and there were several small holes in it. I never aw any leaks/puddles nor smelled any coolant, but it leaked enough to cause the heat to not work and the engine to run hot (I caught it pretty quick as well). Read into how aluminum radiators corrode from electrolysis. This is why many OE radiators are a copper/brass core...it's immune to the same corrosion that kills alum. rads.

Thanks for the response guys. I just drained the coolant. The PO didn't add any coolant. It was probably 90% water. The hygrometer said the water would freeze at 20 degrees F. And it was 14 degrees out that morning. The water must've froze in the heater core which would explain why when I let the car sit for about 3 hours, the heat worked fine. I'm surprised the freeze plug didn't pop out or the block didn't crack.