heater valve help!

[Ronee]

Hi guys,

well now winters here, the Elan has decided that she has no heating and im actually a little icicle when i take her out!

after reading up on here it looks like i need a heater valve, can i just confirm that this is the jobbie i need to buy? we have a 2hr trip to make in a couple of weeks and i cant cope with the coldness!

does the aircon situation make a difference, as my S2 doesnt have it?

http://www.ebay.co.uk/itm/VOLVO-740-760 ... 416db333f2

thank you

[epipete]

Yeah, that's the one I think, however what you need to bear in mind is that in normal use the valve is open (heater dial set to hot) when you turn the heater knob to cold it allows a vacuum to close the valve and hence stop the flow of hot water through the heater matrix. Thus if this has failed then you should be getting hot through the heater no matter what setting the dial is on.

Therefore you need to check that you have a vacuum to the valve before you replace it; turn the engine on, turn the heater valve to cold, pull of the vacuum line to the valve, see if it sucks.

Pete

[GeoffSmith]

I know it's 10p more expensive, but it would be good if you could support Braydons who did us a very favourable group buy a few years ago:

http://www.ebay.co.uk/itm/Volvo-760-740 ... 2577c2452d

[Ronee]

i emailed them a few days ago, but yet to recieve a response as i would have just bought direct and not through Ebay.

i followed the link on WikiLEC

does the fact my car doesnt have aircon make any difference? this is my main concern.

as 'Lily' hasnt gone wrong yet *touch wood* we havent lifted the bonnet apart from putting oil in so havent investigated anything.

[epipete]

Yes, I brought from Braydons and then discovered that my old valve was still serviceable, all be it coming to the end of its life! The first one Braydons posted never arrived but thy immediately sent out another when I contacted them, so good service.

[Ronee]

Yeah, that's the one I think, however what you need to bear in mind is that in normal use the valve is open (heater dial set to hot) when you turn the heater knob to cold it allows a vacuum to close the valve and hence stop the flow of hot water through the heater matrix. Thus if this has failed then you should be getting hot through the heater no matter what setting the dial is on.

Therefore you need to check that you have a vacuum to the valve before you replace it; turn the engine on, turn the heater valve to cold, pull of the vacuum line to the valve, see if it sucks.

Pete

Thanks for the advice Pete, I will check the vacuum. The heating is hot if fan blower setting is turned off for a minute or so and then turned on, but quickly turns to luke warm. So I'm guessing either the heater matrix core is blocking up reducing heat transfer efficiency or the valve is very restrictive, I guess the latter as the coolant appears to be very clean. The temp gauge sits at around 1/4 on the dial (thermostat replaced recently). If the heater is set to cold, it does blow through cold air so the valve seems to be doing something albeit not a great amount.

Gaz

[epipete]

I'm almost certain that during the development phase of the Elan somebody was tasked with ensuring the most difficult and complicated system was used in all areas, this seems particularly TRUE of the heating system!

If you look at the manuals it is intuitive, eventually, but there is a lot to wade through but vacuum is a good place to start.

Pete

[Jeemy]

Is the vacuum valve just meant to hang loose in the engine bay? Mine just came out when I was removing hoses, and I was surprised it just hang supported by the attached and surrounding hoses.....

[epipete]

Is the vacuum valve just meant to hang loose in the engine bay? Mine just came out when I was removing hoses, and I was surprised it just hang supported by the attached and surrounding hoses.....

That is the way mine was too, so I think the answer is 'yes'!

[Ronee]

I'm almost certain that during the development phase of the Elan somebody was tasked with ensuring the most difficult and complicated system was used in all areas, this seems particularly TRUE of the heating system!

If you look at the manuals it is intuitive, eventually, but there is a lot to wade through but vacuum is a good place to start.

Pete

After spending some time on the Elan, I fear it was far from intuitive, on the contrary infact. More questions have been raised, the heater valve in particular. After finding no signs of vacuum at the diaphram feed pipe on the heater valve at all and subsequently no movement from the lever arm when adjusting the temperature inside the cabin. Yet, adjustment to the heater control still allowed the temperature to be altered.

After removing the heater valve from the cooling system, which appeared to ressemble something from the Titanic in the distant future at very best, the heater still operated as it did previously. Infact, the heating has been greatly improved as the coolant no longer has to flow through a restriction prior to arriving at the matrix.

Am I missing something here? The Elan is an S2 if this chances things entirely. The heater flow/direction control is vacuum controlled, there is an audible suction type sound upon turning the dial. A manual flap type noise can be heard upon turning the temperature dial.


Gaz

[epipete]

Hi Gaz

Don't despair! I haven't got the manuals out at present and will check tomorrow but iirc when you set the temp control to cold there are two actions occurring; 1 - an actuator rod extends to the back of the heater and operates a vacuum valve which in turn activates the water valve in the engine bay cutting of the flow of hot water to the matrix & 2 - the actuator rod mechanically closes a flap on the heater box which also restricts the flow of air over the matrix hence it blows cold.

It still sounds as though you have a vacuum leak somewhere.

I'll ponder this further in the morning.

Pete

[epipete]

Gaz

John C provided this diagram in my Heater Rebuild thread:

http://www.lotuselanm100usa.info/heater ... vacuum.jpg

If you can open this up it will show the routing of vacuum for the heater, note that this is a US diagram but the detail still pertains, if it won't open from here grab it from my thread.

Starting at the plenum you can check the vacuum supply at the take off point and at various connections through to Pipe 2, baring in mind that the heater fan etc in his diagram are reversed for UK cars (although the plenum and vacuum res are correct).

But to start, if you reach in, from under the passenger footwell, to the rear bottom of the heater dist unit you can feel the water valve micro switch, this switch is operated by the hot/cold selector knob. Turn the knob and feel the rod move, is it pressing against the switch? With the engine running, and the control set to hot, the switch is not activated so her is no vacuum going to the water valve. Now remove the hose (#6) to the water valve turn the cold on and you should, if the actuator is pressing the micro switch have a vacuum that you can feel at the end of #6. If not then you will need to back track all the way back to the plenum to find out where the loss of vacuum is.

With the engine running, if when you turn the dial on the distribution selector, you can hear flaps being operated then it is safe to assume a supply of vacuum via the branch of pipe #2.

The actuator rod (from the hot/cold switch), in addition to activating the microswitch, also operates 2 flaps in the distribution box which redirect airflow around the matrix allowing ambient air in to the cabin. In operation of the hot/cold dial you should hear the appropriate thunks as these move!

In summary, setting the heater to cold operates a vacuum which cuts off hot water to the heater matrix and also stops airflow through the hot matrix in to the cabin.

Does this help?

Pete

[Ronee]

Thanks Pete, this has helped me out infinitely! The layout of the vacuum system in the diagram above looks insainely complicated

I will take another look when I have time and report back.

Thanks again,

Gaz