Brrrrrrrrr....cold in my CAV....

CliffBeer · 12-30-06, 08:46 AM

Just wondering if someone knows how the heating system works in a CAV mono? No heat (not even a dribble) coming out when the car is up to full temp. I have the toggle switch set to the middle setting and the fan turned on but nada. Is there a heater valve or something which may not be functioning? Thanks in advance.

Pat Buckley · 12-30-06, 10:46 AM

Make sure that the heater hoses are hooked up to the heater and not just looped?

PosMan · 12-30-06, 06:11 PM

Sure you've probably tried this :-

I'm just building my Cav at the moment and there is a water shut off valve behind the dash. Follow the heater pipes from the Air con / heater unit behind the dash and you should come across a shut off valve. This valve should have a cable attached (from the dash) that controls the heat. Make sure the cables connected and the valve is not faulty.

chuck smith · 12-30-06, 06:18 PM

it has a solenoid that when you put the switch to the middle position it opens the valve. Mine keeps slipping off when activated and I bet this is your problem. It needs a retaining sevice(cotter pin) or something. Works great when valve is open. chuck

CliffBeer · 12-31-06, 02:29 AM

Hi Chuck, thanks, you may be right. Let me ask you, what exactly is it that slips off? You mean the wires/leads slip off the solenoid valve? Or the leads slip off the switch or ?

Thanks again.

Canuk40 · 12-31-06, 12:52 PM

Hi Cliff,

Also check the vacumm to the hot water valve dashpot. I've seen them reversed or leaking, either way, no heat. You could also have an airlock in the heater. You can see the valve in the pic below.

Although not in this pic, we fit radiator back flush fittings in the hose entering the heater and fill the car from there. The heaters' vacumm valve has to be propped open while filling the car. FYI

Cheers

chuck smith · 12-31-06, 01:27 PM

Cliff,it is mechanical. the solenoid arm slips over the valve,but mine has no locking devise. I will make one. Take the access cover off like Ian is showing

CliffBeer · 12-31-06, 04:16 PM

Thank you fellas - very helpful, much appreciated. I will do as suggested this week and report back.

Happy New Years!

Bob Childress · 12-31-06, 06:14 PM

Hi Cliff,

This may be a helpful picture. In the upper right is the mechanical lever that I think Chuck mentioned. The actuator rod slips off the lever. My fix was to add a small washer and cotter pin on the end of the lever to keep the actuator rod on without binding. Several of us have had problems with this in the past.

For what it is worth, I drove my car back and forth to work all last week during daily thunderstorms and the heater/defroster seemed to easily keep up even on the lowest fan setting. I also found a source of water leaks where the fiberglass edge in front of the windshield seals against the S/S chassis and around the removable electrical access panel just forward of the windshield.

Bob

CliffBeer · 12-31-06, 10:36 PM

Perfect. Thanks guys - very big help. I'm sure you just nailed it. Will get out to the garage this week and pop the front cover off and make the suggested checks.

Thanks again!

CliffBeer · 01-06-07, 12:22 PM

Quick update here gents - checked the lever arm on the solenoid valve and everything it attached correctly there (the lever arm had not dropped off the actuator), however, one of the vacuum lines (the rearward one) wasn't attached to the item directly next to it (the dashpot?).

Anybody know what/where the rearward vacuum line is supposed to go? I don't see an unattached vacuum line hanging around in the area which would obvoiusly be it.

Thanks in advance!

CliffBeer · 01-06-07, 12:36 PM

OK gents, dumb question above - I now see that the rearward hose is the vacuum actuator for the solenoid valve. In other words, one end of that hose is connected to the vacuum dashpot and the other end is attached to the back side of the solenoid valve. No vacuum, no actuation of the heater valve....doh!!!

Should work now.....going for a chilly drive...will report back.

Thank you!

Dutton · 01-06-07, 12:55 PM

Cliff,

This may or may not help, but years ago whilst racing Formula Ford, I made it a practice to secure connections similar to yours with some real small zip-ties. A racing friend, who had a look at my engine after he experienced a DNF, never had a spark plug lead pop off his distributor after that...

Best,

T.

CliffBeer · 01-07-07, 03:25 AM

Hi Tim!

Good suggestion. I took your advice and secured the vacuum pipe with a little zip tie - shouldn't fall off now!

Situation is improving - took the CAV for a long drive today and got her up to operating temps. Definitely some heat coming out now but it's really not a lot. Only marginally warmer than the 40 degree cockpit unfortunately.

I suspect I need to "burp" the lines for the heater. As suggested above, sounds like the right fix is to install a small valve in line with one of the heater lines to help evacuate any air. I'll give this a whirl tomorrow.

Thanks again.

Gary Kadrmas · 01-07-07, 12:52 PM

Cliff,

Seattle has cold weather? Heater in a GT40? Next thing, you will be asking about studded tires for driving in the snow and ice! Ha-ha-ha-ha!!!

Gary

Gary Kadrmas · 01-08-07, 09:34 PM

Cliff,

Did you get any closer to finding out if air in the system is creating your issue?

Gary

CliffBeer · 01-08-07, 10:49 PM

Hi Gary, thanks, haven't had a chance to "burp" the heater yet. I suspect this just may do it and restore the heating system to full capability.

One question - anybody know the best way to install an access point in-line in the heater hose? In other words, where is the best position to put this, and, any suggestions as to specific device?

Thanks.

Neal · 01-09-07, 10:16 AM

Cliff,
I recall seeing a small inline fitting with a schrader valve installed that was to be installed at the highest point in the system. I'll try and locate the source.

Lynn · 01-09-07, 11:57 AM

I'm going to make the assumption that the heater lines come off of the radiator lines once they reach the front of the car, one before the radiator and one after it. If this is not the case, then, in the words of Rose Ann Rosanadana, never mind.

Otherwise, with the engine running and heater on, try pinching off the radiator line between the inlet heater hose and the radiator for a bit to force more water through the heater core to clear any air lock. Not saying that you shouldn't put a valve to release air during fillup mind you.

Bob Childress · 01-09-07, 03:29 PM

Cliff,

All the suggestions here are good although I don't believe anyone has suggested wearing a coat and/or waiting for global warming.

Here are three pictures to help. Bleed valves could also be added in the heater lines or the main radiator hose instead of to the radiator itself. Also note the brackets to anchor the top of the radiatior. AutoFutura has add on brackets to do the same job. Finally raising the rear overflow catch tank in the engine compartment will naturally get rid of a lot of air in the system especially if you let the car idle with the nose down.

Bob