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Hello,

Today while driving, I noticed that a small bit of heat was coming through the vents, even when set to cool. From researching posts here it seems that the heater valve might nee replacement. It's not too expensive... and colder weather is coming so I might leave it until next spring.

Anyway, I was just thinking.... I was trying to daignose some small amounts of oil in the coolant, and I did a coolant flush... and in the process I ensured I had the heater set to heat and then ran baking soda through the system a few times.

Is there any chance that this could have affected the heater valve... that I could have dislodged some gunk which is keeping it open a bit?

I don't really know how it works but I guess the coolant must run into the heater valve behind the dash?

Any tips gratefully received.
 

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Heater Valve

My '69 Spider's heater stopped blowing hot air about a year ago. I thought that the valve seal had swelled and blocked the valve shut and that I surely needed a new valve, or at least a new valve diaphragm. When I finally tackled the job last month, what I found was a collection of semi-crystalline junk blocking the valve. I cleaned the junk out and saved the replacement diaphragm for another day. The way I store things, I'll probably never find it when I actually need it. You might have a variant of the same problem.

Although I ended up not having to take the heater totally out of the car, the contortions required to get to the valve and disassemble it, be it in a GT or a Spider, are such that you don't want to do it twice. So be prepared for the worst and have the new valve on hand before you go in.

Regards,
Bob A.
 

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On a 76 Jr you probably have the black plastic heater valve. Yes it's up under the dash, attached to the left side of the heater radiator. If it's internally like the earlier two-piece metal valves, the rubber seal tends to swell closed over the years, preventing water from passing. Maybe your flushing and chemicals did the reverse, opening it up some? Hard to say. I don't know of a way to rebuild the plastic valves; I think you have to replace, though I wouldn't worry about it til it starts leaking.

You're sure the lever/cable has closed the valve fully?

Andrew
 

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Why don't you try to bleed also the heater valve? See the arrow in the photo
Er, actually that's not a bleed screw but part of the cam assembly that raises or lowers the internal rubber diaphragm. No coolant is normally present in the top half of the tap unless the diaphragm is punctured in which case it's called a LEAK :eek: Ask me how I know..........:rolleyes:
 

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Ok. I never had the chance to bleed the system from there, too. I can't recall now the source, I've read in a tech book in a diagram looked something like also a bleed there...Maybe I'm wrong. And while I full restored the heater sytem, I noticed that you mentioned. In any way, why not to have a screw driver there at least to adjust the valve? In a friend's Junior, the valve didn't opened or closed all the way, since we looked at this screw.
 
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