New member here (long time reader… etc.):
We have a question for the hive-mind.
We bought a new-to-us ’17 XC90 for my partner (we’ve both owned, and I’ve worked on many-many Volvos, She wanted something “new” and “fancy” and “wouldn’t break for a while”).
Car’s got 110,000 miles. (that’s basically a new car for us)
About 3 months in, she got a random “cars running hot, pull over and let it cool” message. by the time she slowed down the message went away… I checked it out and all seemed fine.
2 months later… another “over temp” message… very brief. Then perhaps another a week later.
(I wasn’t up to date on code reading intricacies for SPA cars at this point so no codes to report unfortunately).
Decided this was not something I had time to investigate so booked it at the local dealer (Figuring ViDA would work its magic).
Literally on the way (a blistering cold day) car immediately gave the “over temp” message. (Also heat stopped working).
I pulled over. Engine and hoses nice and cool, reservoir full.
Waited a few minutes… made it half way there an got “over temp” then “overheat” messages in rapid succession.
S**t… getting real.
Let it cool 30min (again bitter cold day and hoses and block are only slightly warm to the touch. reservoir full.
Restarted drove carefully the rest of the way. No messages.
Dealer calls with bad news…”Failed coolant leakage test with no external leakage found” and “Exhaust Gasses detected in coolant”
Likely blown head gasket, $8k (!).
F-that. had the car towed to my shop.
I have done half a doz. leak tests myself on this now.. will hold 20# all day.
Zero coolant loss and I couldn’t detect any exhaust in the coolant with the blue-fluid testers I have.
(BTW… I have no reason to suspect the dealer was “up to something”… but wanted to triple-check)
I really don’t want to do this head (the turbo/supercharger and its location intimidate me) as I have done numerous others on earlier cars (the potential software resets, scripts, updates, etc. unnerve me as well).
Made the leap to Vdash (wow, that program needs a F1 help menu!) and retrieved codes… the relevant:
ECM-P021700 Engine Coolant Overtemperature Condition.
ECM-P26DC00 Engine Sound Control “A” Circuit Low.
ECM-P301900 Electrical Coolant Pump – Low Fluid Level.
BCM-C10157A Vacuum Supply. Mechanical Failures. Fluid leak or seal failure.
I was unable to find a relevant issue here or elsewhere on the web and no good manuals, so I threw some dumb-money/parts at it… New thermostat and pump from FTC Euro.
Went in slick and coolant vacuum worked like a charm.
Car ran nice and cool (now monitoring the engine temp with Torque).
Temp cycled really well at idle. Around 80C
Heat on it would dip and come up gradually nice and predictable.
Tried at increased engine speed… temp moved into the 90’sC and again settled into a nice pattern.
Took it for a ginger test drive. … Flawless (to my eyes). kept driving loops around the block at all speeds and heat on and off… all great… Nice and predictable. mid 90C cycling nice and regular.
Took it up a neighboring hill on the highway and went up and down a few times at 65mph… still good. 90’sC
Congratulating myself on the way home got behind a slow moving truck and the temps creeped to 100C and then cycled back down.
Got home all happy and sat in the car for a few minutes as it idled and turned up the heat… hmmm.
Temperature starts creeping up… heat is blasting cold air(!!)… just keeps climbing until 115C when I shut it down.
When I shut it down radiator fan is blasting and the temp stays pretty constant and then slowly drops over 15 min to upper 90’s. (car stopped)
Now I’m perplexed and curious… so…
I start it again… slow climb from (90 to 95, I try driving on my driveway to see if engine speed/load changes anything… not really… slowly creeping up. as I turn around and head back to the shop it spikes to 115… (!) I shut down to cool.
300 feet to the shop doors…
I restart and creep forward toward the shop and temp starts climbing… Perhaps coincidentally, I bounce through a pot hole on my drive (at 5 MPH) and the temp drops like a stone to 90C… then cycles in the 90s once then shoots up again…
I shut down at the shop doors…
WTF… I say to myself…. as I watch the temp of the stopped car sink back down below 100…
When its at 90 I start it again to get into the shop and I hear the distinct gurgle of a bubble in the heat exchanger.
How’d that get there???
I assume I am doing the head gasket at this point but any other ideas before I spend the next several days crawling over the top (and under the right wheel well) of this thing??
Still feels like uninformed-repair but a head gasket just starting to leak only under combustion pressure and at high block temperatures feels like the most obvious solution at this time.
I would appreciate any thoughts you all might have.
-A