Bentley Publishers - Technical Discussions : Heater core temp ...

BonBon

Posts: 5
Registered: 01/06/08

Heater core temp
Posted: Aug 20, 2009 5:34 AM

I notice that the heater core heats up in the summer - even though the heater control valve appears to be operating correctly.
Is this normal?
Presumably the core is heating up via the hose that does not go via the valve.
(The only other possibility is that the valve is not fully closing....and I don't want to open the valve to check, if what I see is normal operation)

Charlie

Posts: 4,669
Registered: 12/09/03

Re: Heater core temp
Posted: Aug 20, 2009 8:42 AM

in response to: BonBon

Reply

Heater valve is worn,leaking past shutoff seals.

BonBon

Posts: 5
Registered: 01/06/08

Re: Heater core temp
Posted: Aug 20, 2009 8:48 AM

in response to: Charlie

Reply

Are you saying that the core should remain ambient temp if the valve is working properly?
I somehow doubt that - as the inlet hose passes into the core with no obstruction - wouldn't one expect the heat to gradually diffuse into the core?

Charlie

Posts: 4,669
Registered: 12/09/03

Re: Heater core temp
Posted: Aug 20, 2009 8:54 AM

in response to: BonBon

Reply

Not sure on hose routing, but don't think the core should be hot when the valve is closed. I understand what you mean about convective heat transfer, so there may be some heat, but the colant is not passing through the core. There may be some, but should be negligible.

BonBon

Posts: 5
Registered: 01/06/08

Re: Heater core temp
Posted: Aug 20, 2009 9:07 AM

in response to: Charlie

Reply

The fact that it is expected to have neglible heat rise with the valve closed is noteworthy.

The best would be to hear from another owner.
To feel the core inlet you just need to remove a single screw from the trim near the driver's right knee (LHD)

BonBon

Posts: 5
Registered: 01/06/08

Re: Heater core temp
Posted: Aug 21, 2009 10:23 AM

in response to: BonBon

Reply

Good call Charlie,
Removed and tested the heater control valve by blowing through it.
When set at a min temp ie "closed" it was approximately 10% open which was enough to heat up the core.
I proceeded to open the valve. Both the rubber protecting the plunger and the valve seat itself were "corroded".
I cleaned them and smoothed them up (as best as possible until I get a new one) and the seal was 99%. This was enough to keep the core cool after a 20 minute drive.
Cheers

BonBon

Posts: 5
Registered: 01/06/08

Re: Heater core temp
Posted: Aug 21, 2009 10:23 AM

in response to: BonBon

Reply

Good call Charlie,
Removed and tested the heater control valve by blowing through it.
When set at a min temp ie "closed" it was approximately 10% open which was enough to heat up the core.
I proceeded to open the valve. Both the rubber protecting the plunger and the rubber valve seat were "corroded".
I cleaned them and smoothed them up (as best as possible until I get a new one) and the seal was 99%. This was enough to keep the core cool after a 20 minute drive.
Cheers

Message was edited by: BonBon