V50 General : Weird Intermittent Coolant issue

[FunkyMelon]

From my experience, there should be no pressure when releasing from cold, so I'd keep an eye on that...

They operate under pressure yes, but when cold there should be no pressure.

Does the engine temperature sit in the middle now when using it? No fluctuations?

[Bungo]

Originally Posted by TallPaul1975

Think will have to take it to the Volvo main dealers and get them to connect it to a diagnostic software. Hope they don't rip us off too much, I know they charge between £60 - £140 just to read it depending on what they find.

Do you have a volvo indy nearby ?
I think £60 is the going rate anywhere to be honest, I don't know why they would charge upto £140, get a quote first.
I think temp sensor or wiring to it most likely.
You will still need to address dpf situation at some point.
All the best

[TallPaul1975]

Well I have received by head gasket tester kit, tested it and the fluid remained blue also no air bubbles.

Did the same thing again today, ok driving there 20 miles, and about 14 miles on the return trip temperature started to rise, thought I'd try a few things to see if anything makes a difference. What I noticed that if I increase the revs the temperature starts to fall again back to normal (90 degrees)

Also stopped off at a supermarket close to home on the return trip, no fans were on. Then when I arrived home approx 2 miles, after switching the engine off then fans carried on running for a good 5 maybe even 10 mins.

[Tannaton]

I don't think it is the sensor or the wiring - that would tend to fail hard (i.e. short circuit or open circuit - gauge on maximum or zero). It's not beyond the realms of possibility though that the sensor is failing.

It could also be a blocked radiator core or the radiator has corroded/too many pressure washes and the fins are damaged/missing?

The fact that it drops when you rev does point to a air/gas lock or blockage

I think the fans are operated by a separate switch/sensor