704CH
Well Known Member
So I am early on in my phase 1 and I had to use cabin heat the other day. Funny thing is my heat won't stay on, it wants to pull itself shut. So I am sure to fix I need to tighten up the spring that ratchets on the cable. Maybe this problem is common?
But I started thinking.. about the pressures that might be causing the door to want to close and decided there are 3 pressures involved.. 1) Cabin Pressure, 2)Pressure above the engine/baffles where the heat intake is, and 3) pressure below the engine/baffles where the box overflow is.
In this case when I hold the heat on heat comes into the cabin, so clearly pressure above the engine is greater than Cabin Pressure.
But the fact that it wants to push close, means that pressure below the engine is greater than above the engine, which I don't understand.
This would mean that pressure is building at the cowl exit around my exhaust, greater than on top? My CHTs are low enough to know I am getting plenty over the engine even though I am still breaking in.
Any thoughts on this? What else could be causing this?
But I started thinking.. about the pressures that might be causing the door to want to close and decided there are 3 pressures involved.. 1) Cabin Pressure, 2)Pressure above the engine/baffles where the heat intake is, and 3) pressure below the engine/baffles where the box overflow is.
In this case when I hold the heat on heat comes into the cabin, so clearly pressure above the engine is greater than Cabin Pressure.
But the fact that it wants to push close, means that pressure below the engine is greater than above the engine, which I don't understand.
This would mean that pressure is building at the cowl exit around my exhaust, greater than on top? My CHTs are low enough to know I am getting plenty over the engine even though I am still breaking in.
Any thoughts on this? What else could be causing this?