Cabin heat - too much of it!

[knute]

As the weather warms up around here, I'm again appreciative of last fall's fix to the heater box flapper!  For the first 5 years that I owned 66Q, it was not possible to fully shut off the heat, and summer flying meant lots of icy drinks in a cooler in the back seat.  I don't know how the heat is controlled on the later models, but on the early models it's a flap that controls the flow of hot air from the muffler shroud, and the gasket on that flapper doesn't have much pliability after 45 years.  The fix is a new gasket, but make sure it gets a rivet, because the first time it got fixed (sans rivet) the heat melted the adhesive, the gasket moved, and the flapper didn't seal.

If your Mooney cabin runs hot, this is a wonderfully pleasant fix!

I'm looking forward to some great summer flying this year.

[jetdriven]

Our 77 J has a slide type valve, and it always leaks.  Looks like a similar valve from 1966-1978.  I noticed that this airplane was a pretty hot airplane to ride in, even at altitude.  Oshkosh trip we sweated a bit.  I remarked to my partners and they thought I was being a wuss.  I plugged a massive gap in the oerhead plenum and installed some foil mylar insulation in th ceiling panel.  Heat continues.

Anyways, I noticed, especially when opening the cabin door after landing, hot air would come flowing out of that center vent. Like a hairdryer. I took the slide valve apart and it was working as well as designed, but still leaks hot air.  I measured it with my raytech and its around 100 degrees with an OAT of 60. Pull the cabin ar full open the temp is around 75 or so, but not cool enough.

Our fix is sitting in a box at my house, just arrived.  a 1979 M20K heater box, with a real flapper and gasket, not a slide valve.  These do not leak as much, if at all.

[moontownMooney]

knute, can you give me any details about the rivet you speak of?  I think we've had this exact scenario happen to us in our '68 M20F.  See my other post, linked below, with pictures at the bottom.