Heating system flapper valves
04-04-2009, 06:24 PM
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Heating system flapper valves
Planning to put the car on the road after winter hybernation 
. Remembered that I had poor heating last spring so I checked the flapper valves. They were both stuck! Removed both valves and found that they are two piece castings held together by rivets. Drilled out the rivets using a 4 mm drill bit and was then able to separate the halves. The butterfly shaft is supported by plastic bearings at the ends. They have a flange that exerts axial pressure on the shaft. The bearings had shifted position causing the shaft to jam. As I was not able to remove the bearings without destroying them I trimmed the bearing flanges down using emery cloth. Assembling the valve using M4 bolts checking the butterfly action, disassembling again, trimming some more on the flanges until the action was smooth and light. I stopped trimming when the butterfly required only very light finger pressure to move, thinking that if it got too loose it might start to rattle. Now that I know they function properly I will clean and install them tomorrow. But tonight, 
. Remembered that I had poor heating last spring so I checked the flapper valves. They were both stuck! Removed both valves and found that they are two piece castings held together by rivets. Drilled out the rivets using a 4 mm drill bit and was then able to separate the halves. The butterfly shaft is supported by plastic bearings at the ends. They have a flange that exerts axial pressure on the shaft. The bearings had shifted position causing the shaft to jam. As I was not able to remove the bearings without destroying them I trimmed the bearing flanges down using emery cloth. Assembling the valve using M4 bolts checking the butterfly action, disassembling again, trimming some more on the flanges until the action was smooth and light. I stopped trimming when the butterfly required only very light finger pressure to move, thinking that if it got too loose it might start to rattle. Now that I know they function properly I will clean and install them tomorrow. But tonight,
04-11-2009, 09:02 AM
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airfan, good info, thanks. I think I have the same problem. I get no heat into the car. Lots of posts about servo valves, but before I get into those I want to troubleshoot the easy stuff first.
One thing pointing me to the flappers is the absence of a 'rattle' noise when I close the door (it used to be there and is apparently a sign of a normally functioning flapper).
Questions: Did you have to remove the flapper assemblies to check whether they were jammed, or can it be done mounted? Can you provide a litle more detail on how you removed them from the car ?
Thanks!
One thing pointing me to the flappers is the absence of a 'rattle' noise when I close the door (it used to be there and is apparently a sign of a normally functioning flapper).
Questions: Did you have to remove the flapper assemblies to check whether they were jammed, or can it be done mounted? Can you provide a litle more detail on how you removed them from the car ?
Thanks!
Last edited by breale01; 04-11-2009 at 03:49 PM.
04-11-2009, 11:13 AM
#3
Burgled
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airfan, good info, thanks. I think I have the same problem. I get no heat into the car. Lots of posts about servo valves, but before I get into those I want to troubleshoot the easy stuff first.
One thing pinting me to the flappers is the absence of a 'rattle' noise when I close the door (it used to be there and is apparently a sign of a normally functioning flapper).
Questions: Did you have to remove the flapper assemblies to check whether they were jammed, or can it be done monted? Can you provide a litle more detail on how you removed them from the car ?
Thanks!
One thing pinting me to the flappers is the absence of a 'rattle' noise when I close the door (it used to be there and is apparently a sign of a normally functioning flapper).
Questions: Did you have to remove the flapper assemblies to check whether they were jammed, or can it be done monted? Can you provide a litle more detail on how you removed them from the car ?
Thanks!
