V70 2.4D Running Hot
 

Hi I own a 2010 V70 showing 210k. I have posted before regarding running hot, but decided it would be better to do a clean update in the hope that someone can suggest anything that I've overlooked. I will start by listing the work carried out so far:-

1) Check for combustion gasses in the cooling system carried out. Negative.
2) New Volvo Thermostat fitted.
3) New Volvo temp sensor fitted.
4) Cooling system was cleaned and flushed.
5) New water pump fitted.

Symptoms

If the car is driven at 55-60mph with the A/C switched off the live data shows 105-112 deg C. The car has been driven for 50+ miles like this. Drive faster or switch A/C on, and the temp increases until ‘Engine running hot, Slow down.’ Warning lights up. As the temp increases past 94 deg the cooling fan comes on and increases in speed from 12%-94%. This has been checked and verified. The system does not lose water. The car has been driven approx 1200 miles since the fault appeared. The car heater works. The top hose gets very hot, the bottom hose, luke warm.

6) New radiator fitted. Back flush (TODAY)
After the new radiator fitted the temp was monitored at 102deg whilst stationary, the garage spent an hour trying to bleed any air from the system. They feel there is possibly still air in the system.
I took the car and drove 10 miles home (55-60mph) monitoring temperature. It rose to 107deg C but cooling fan on live data remained at 0% . 2 miles from home I stopped and switched off the engine for 5 minutes. On restarting the temp was 97 deg then almost immediately dropped to 88deg and the fan showed running at 12%. 100m from home the engine temp started rising again. I have removed the cap from the expansion tank and left over night. I should have scrapped the vehicle when this started but made the mistake of spending money on it. Please any thoughts…..

fresh coolant? or just water? was the thermostat fitted correctly with the bleed hole at the top?was a genuine volvo water pump used ? iv seen cheap alternatives with plastic impellers fail the first time an engine overheats.

Yes fresh coolant, but not Volvo water pump. The garage I use has changed water pumps on My previous V70 and S80 without a problem. As for the Thermostat, mine is the unusual thermostat at the back of engine near bulkhead. A very strange design, new thermostat permanently fitted into a complete housing with long metal pipes. Had to be Volvo at a cost of £300!

It's a pain chasing such faults.

If your purchased pump had a metal impeller I wouldn't expect there to be an issue. Specifying Volvo only is fine if you've got money tree's in the back garden.

Your hot top, cold bottom hose is classic trapped air but are you also confident that the lower portions of the radiator are clear so that flow is unrestricted other than when the thermostat is closed?

Borrowing/buying an infrared thermometer would be good to take a snapshot of individual cooling system component temperatures which could help identify an issue.

One method of removing air is to elevate either the expansion tank or the corner of the car where it's situated, ie jack under front o/s of the car. Then run the car with expansion cap off, engine running heater on hot, watching for bursts/bubbles of air in the header tank, coolant at the ready to top up with.

Radiator removed and replaced with new unit yesterday. Yes bottom hose feels empty so there is defiantly a restriction some where. I presume that hose goes to the thermostat which is a New Volvo part.

When the coolant was changed, were the heater pipes removed to flush the heater core?
After a run and with the engine still running, are both heater pipes in the engine bay equally too hot to hold?
Can the climate system push out uncomfortably warm air when up to temperature and set to maximum?

Ill check the heater pipes. Are they difficult to get to? I think one is hotter than the other.
Thanks

The 2 hoses are on the back wall of the engine bay so coolant can flow in and out of the heater core in the cabin.

Access to feel hose temperatures is normally decent.

dont skimp to save a few quid on important parts . remember this. the quality is still there once the price is forgotten bont buy cheap or you may end up buying twice . ask me how i know:teeth_smile:try filling the system from the radiator drain point.slowly

With regards the cooling circuit flow, does the heater circuit hold enough capacity and if blocked likely have an effect on what the main cooling system is doing? if the heater controls are set to cold, theoretically it's not involved in engine cooling - or is it on this vehicle?