S60 D5 Cooling issues

[webbyd5]

Hello everyone in Volvo land.
Yet more problems with the old girl S60 D5 2001 165k, after sorting a monumental amount of problems with the turbo etc, I now have a new problem. There is a rediculous amount of pressure building up in the cooling system.

It all stems from my radiator springing a leak. I nipped down to Halfords and purchased a bottle of Radweld gold. In my impatience I waited a good 3 hrs for the engine to cool down but there was still lots of pressure in the system so l released it through the lid of the expansion bottle and a fair bit of coolant came out. This was still not enough to top up with Radweld so I took off the coolant pipe that goes to the thermostat housing. After making room I put the Radweld into the system then fired her up to get rid of any air locks. Left for about 30 mins with cap off and all was good. Screwed cap back on ran it down the mway for about 20 mins and stopped at home..... leak was gone no pressure all good! Topped the coolant up job done.

4 days later after driving through rush hour traffic back from work ... temp gauge is bang on normal but there is a hissing coming from under the bonnet... there is coolant being pressurised and forced through the cap. The pipes were rock hard and I thought the worst.
Since then I have had the cap off for hours on end trying to bleed the air out but with no joy. Today I took the pipe to the thermostat housing off and wedged the thermostat open with a screwdriver within the housing. Re attached pipe and all was good temp going up and down as I moved along the road and rising as I came to a standstill but.... the pressure was still there so I don't think it's a dodgy thermostat.
Coolant temp is reading 81 -87. Both top and bottom pipes get red hot but the fan has not kicked in once.
Question is - is this something easy to fix or is it a blown head gasket and time to get rid?

Any help as always is much appreciated
Dave

[cheshired5]

From another thread.....

Originally Posted by cheshired5

Before starting from stone cold, you need to remove the expansion cap to release any residual pressure then replace the expansion cap to normal tightness then start the car.
After about 10 seconds, turn off engine and undo the expansion cap. If it hisses, that's a very good indication of HG failure.
Also smell the expansion filler neck for combustible/smokey /fuel type smells.

[5cilinder]

If both bottom and top hoses get very hot ,your thermostat is working otherwise there couldnt be hot hoses there if it was closed
The fan should be coming in at 105 c
A few things:

The temperaturegauge in the car is dampened wich means roughly that between 75c and 105c its in the middle so if you want to know exact the temperature buildup measure it with your torque app

The temperature sensor itself could be broken and give false signals ,you can verify the correct workings to measure the ohms at different temperature intervals and see if it matches up with the list
i dont have vida at hand now but the values are roughly universal


Coolant system:
The heatercore is placed in serial in the cooling system if that one clogs up it severly hinders coolant circulation wich give the symptomes you are getting .
Ive seen a few cars with the same system thinking their headgasket is blown with an in serial clogged heatercore
Especially the lifetime coolant fillings advise from volvo is wrong here. replacing the coolant once in a few years will definitly prevent these issues , they advised these lifetime fillings because the innerblock is coated with a gold coloured coating but the heatercore, heatexchanger and radiator are still bare aluminium wich will first deteriorate the coolant and if the dopes are used up (longer than without the coating) the coolant will oxidate those components.

You can get your heatercore out and inspect it and replace if needed , bypassing is also possible but is suboptimal and creates extra weaknesses if done poorly
Does it get hot btw in the car if the engine is at operating temperature?

Headgasket is a possibillity (with these symptomes) but its not likely , its an all out aluminium block where almost no blown gaskets are sighted .
It can be but adress first the above issues

[webbyd5]

Hi guys,
Cheshired5 I have tried the method in your thread I can confirm that there was no pressure from stone cold starting.
5cylinder the car gets very warm inside when at operating temp, I can see your theory with the heater matrix. I have now ran the car till the fan kicked in it kicked in at 101c according to torque. The pressure in those pipes is unreal now so will have to wait till they have cooled to release.

I think best bet is to try and blast system out with hose pipe what do you think?

[cheshired5]

You have a physical blockage (debris/stuck thermostat) an airlock or your water pump is knackered.

As the coolant temperature increases and the pipes harden, is the radiator top hose too hot to hold?

[webbyd5]

Yes mate really hot

[cheshired5]

Ok, so is the bottom radiator hose equally hot and under high pressure?
Are both heater pipes too hot to hold and pressurised?
What about the feed and return hoses on the top and bottom of the expansion tank?

[webbyd5]

The bottom hose eventually gets a too hot and pressurised as does the small return pipe from the radiator. A lot of water seems to be returning back into the bottle through the return. I haven't checked the heaters or feed pipes as yet but will do tomorrow and post on here 👍

[5cilinder]

The returnpipe of the expantionvessel should carry a healthy stream of coolant
IN fact if there is a blockage in the system they expantiontank than functiones as a shortcut to partly relieve pressure but not heat
That hints that the waterpump seems to be working

Have you tried to control the temperature with the heater on max blow?
Did you check the radiator at both sides on blockage on airflow etc?

[5cilinder]

To be sure double check thermostat
Warm the car up from cold and continue feel the top hose to check when the heat starts flowing and check at wich temp
Mind that the thermostat has a tiny bleedhole/valve wich will small amounts of coolant trough anyway