XC90: Intermittent temperature/shift issues

[Tannaton]

Originally Posted by Kev0607

I'm suspect of the water pump, which isn't genuine.

You purchased a "kit" that had a pump in it. Genuine Volvo cam belt kits don't include a water pump. The reason being is they're so reliable that they don't need to. I think the seller likely added the pump and made his own "kit", as kdst5 said above. Its likely that pump is a cheaper aftermarket one, which could create problems.

A water pump is far cheaper than a head gasket. I'd suggest you buy/fit a genuine pump (buy it from Volvo) and take it from there.

When you said you had the coolant changed, what colour is the coolant? Genuine Volvo coolant is a blue/green colour. If your car has another colour coolant in it, change that and replace it with genuine Volvo coolant too.

I'd be suspecting low flow from the waterpump also...

[TruckbusUK]

I would concur, the OP was asked earlier on in the thread if the pump was original or not (I am guessing not,) but so far he has not confirmed.