Pressure in radiator hoses

[StanC]

I apologise if I'm missing something here, but with every car I've ever owned in sixty years of driving, once the engine is up to operating temperature and the coolant is pressurised (to correct pressure) the hoses always feel very firm to the touch. On my current 960 3litre B6304, which I've run for 27 years, the hoses are completely unyielding at operating temperature/pressure and I know I'm using the correct header tank cap. It might be that Casheye just doesn't have a problem?

Stan.

[Forrest]

If you were able to open the coolant cap without a rapid release of pressure that suggests that the system was not over pressure.

Were both radiator hoses firm to the touch? And hot? At 80°C if your 87°C thermostat is working correctly then the radiator would be out of circuit anyway.

[volvo always]

My 940 B230FK has always had firm rad hoses when up to temp from when I got it in 2016/7 on 184,000

My 240 GLT were always rather soft. B230E

940 no sign of HG going, no coolant loss and shortly after buying drove to Fishguard from the Midlands then on the ferry to Rosslare and never missed a beat in the 8 hour drive. Now on 210,000

James.

[Casheye]

Originally Posted by StanC

I apologise if I'm missing something here, but with every car I've ever owned in sixty years of driving, once the engine is up to operating temperature and the coolant is pressurised (to correct pressure) the hoses always feel very firm to the touch. On my current 960 3litre B6304, which I've run for 27 years, the hoses are completely unyielding at operating temperature/pressure and I know I'm using the correct header tank cap. It might be that Casheye just doesn't have a problem?

Stan.

NO, you could be right. There might be absolutely nothing abnormal about the amount of pressure in the hoses. To me and a few other people (friends who are mechanics, own race cars, drive HGVs etc...) the hoses in question seem overly pressureised. I'm just trying to ascertain a potential reason for this. As I don't have another identical volvo to hand to compare I'm going on the assumption there's a problem until I'm convinced there isn't.

Originally Posted by Forrest

If you were able to open the coolant cap without a rapid release of pressure that suggests that the system was not over pressure.

Were both radiator hoses firm to the touch? And hot? At 80°C if your 87°C thermostat is working correctly then the radiator would be out of circuit anyway.

I wasn't. That's why I said I opened it slowly. I should have clarified that there was plenty of pressure hiss when unscrewing the cap.

And yes, and yes.

And I also found this strange but then the fluid that is in the expansion tank is;

1 - furthest away from the heat of the head

2 - Presumably passed through the radiator first which would mean it wasn't a great representation of the temp at the thermostat or in the head?


I'd also mention that when I returned from driving it, and after sticking the temp guage in the expansion tank. I screwed the cap back on and left the car running for another 20 minutes after which the radiator (electric fan) came on which made me believe that the coolant had indeed reached or exceeded it's standard operating temp.

I checked the temp of the coolant in the expansion tank after another 5 minutes of the fan being on and it was down to 70c which makes me think that this isn't a realistic location for accurate readings


It's also worth mentioning that the hoses never feel like they're holding an abnormal amount of pressure when the car is turned over from cold and just left to idle while parked. It's only after it's been driven that the pressure really builds up.

[lynns hubby]

I would expect the fan to kick in after long periods idling on the drive as there is no forward movement of the car to give airflow for exchanging heat from the radiator there fore the fan kicks in to do the job.
Also despite what your temp gauge shows at idle, full operating temp is never achieved until the car has actually been driven.
To be honest, unless you feel that one of the hoses (usually top one) is about to burst, or be blown of the connection it seems normal to me.
I do appreciate though that it is a little difficult to quantify if you are not used to these things. Have you felt the sort of pressure on hoses from another car straight off a run. Not necessarily another 940 any other petrol car? Would give you an indication of the need to worry or not.

[baggy798]

I'll see if my hose gets stiff tomorrow.

[360beast]

Originally Posted by baggy798

I'll see if my hose gets stiff tomorrow.

Sounds like a new movie is being made here...

Carry On Volvo

[griston64]

Originally Posted by 360beast

Sounds like a new movie is being made here...

Carry On Volvo

The innuendo possibilities here are endless

[volvo always]

More like carry on in your Volvo!

[baggy798]

Checked out my hose after a run tonight. I could squeeze it down to half it's diameter quite easily. It was quite hot and I gasped several times in pain, but managed to maintain a firm grip upon the centre 'shaft' section. If I build up a steady sequeezing rhythm, the liquid in the expansion tank can be made to erupt up into the air!

I was going to take a video but I'm very shy.