1967 M20F: Removing my old windows is difficult - please help!

[Matt Seegers]

I have a 1967 M20F and I'm changing out the windows. 

First issue: the old windows are sealed on to the [interior] metal so tight that I can't get them to budge.  I've removed all of the screws, but they are still held [very tightly] in place with sealant.  There's no room to get a blade between the metal and window without causing damage.  Has anyone dealt with this issue - if so, what's the solution?

Second issue: several of the screws/nuts across the bottom of the windshield seem inaccessible without removing some avionics.  I can access most of them through the exterior (cowling side) avionics panel, but there are 4 nuts that are completely crowded out.

[MikeOH]

Just a possible suggestion as I have NOT done this: Use a heat gun on the inside to soften the adhesive, and then force a putty knife with a tapered blade between the window and frame on the outside.  I.e., press in and away from the frame.

[N201MKTurbo]

Buy a skin wedge from ATS and shove it in between the windows and skin. It won’t hurt the skin and probably the windows. Work your way around the windows. They will eventually peel off. They are sealed with tank sealant. It is tough stuff. 

[ProtoFly]

On 11/26/2025 at 7:34 PM, Matt Seegers said:

I have a 1967 M20F and I'm changing out the windows. 

First issue: the old windows are sealed on to the [interior] metal so tight that I can't get them to budge.  I've removed all of the screws, but they are still held [very tightly] in place with sealant.  There's no room to get a blade between the metal and window without causing damage.  Has anyone dealt with this issue - if so, what's the solution?

Second issue: several of the screws/nuts across the bottom of the windshield seem inaccessible without removing some avionics.  I can access most of them through the exterior (cowling side) avionics panel, but there are 4 nuts that are completely crowded out.

Take pictures and copious notes please.  I'm going to be tackling the same on my 1970 F in the spring.  Supervised by my A&P/IA, of course...

[Echo]

I replaced mywindows in my first Mooney years ago.  I say this with the most compassion, If THIS is a roadblock you are way out of your comfort level and need to get assistance.  Removing the old plexi is the easy part in the process.

[Old Chub]

another option for cutting through the window sealant is to use two short 1/2 diameter dowel rods with heavy safety wire wrapped around with about 12 or more in between.  It takes two people (one inside and one outside) but you can get the wire started between the window and outside skin then wrap around dowels and saw your way around the window.   Still not easy but if done correctly will not damage aircraft skin. 

[N201MKTurbo]

1 hour ago, Old Chub said:

another option for cutting through the window sealant is to use two short 1/2 diameter dowel rods with heavy safety wire wrapped around with about 12 or more in between.  It takes two people (one inside and one outside) but you can get the wire started between the window and outside skin then wrap around dowels and saw your way around the window.   Still not easy but if done correctly will not damage aircraft skin. 

No need to get dowel rods, just grab a couple wrenches from the tool box.

[Matt Seegers]

I got it done and it was relatively easy, although it took two people.  I combined the advice from MikeOH and N201MKTurbo.  I got a heat gun (Home Depot) and a skin wedge (Amazon) and [from the outside] had my son use the heat gun while I used the skin wedge to separate the plexi from the metal skin.  It went pretty quickly once we got a rhythm. I then used the heat gun again on the inside to scrape off [using a putty knife] the residual sealant.

Thank you for the advice everyone - I appreciate it!

- Matt

[Shadrach]

On 12/9/2025 at 12:37 PM, Matt Seegers said:

I got it done and it was relatively easy, although it took two people.  I combined the advice from MikeOH and N201MKTurbo.  I got a heat gun (Home Depot) and a skin wedge (Amazon) and [from the outside] had my son use the heat gun while I used the skin wedge to separate the plexi from the metal skin.  It went pretty quickly once we got a rhythm. I then used the heat gun again on the inside to scrape off [using a putty knife] the residual sealant.

Thank you for the advice everyone - I appreciate it!

- Matt

Are the new windows installed?