TKS filler cap help

[Rmnpilot]

My TKS filler cap is beyond difficult to remove or install.  I saw a previous topic from 2017 where the recommendation was silicone spray, lithium grease or to replace.   Anyone have any updates?  I’m afraid I will rip the hinge off on the filler door.   It can’t be designed to be this difficult.  I’ve looked over the threads and while they are all designed as square, they aren’t in bad shape.  
 

[LANCECASPER]

@CAV Ice Any suggestions on this?

[milotron]

I had this issue on mine when I first got it. I make a point of 'lubing' the threads with TKS when I fill it up. I didn't want to risk contaminating the TKS with any kind of lube or solvent.

I also don't crank it down hard, just barely hand tight. There is no way for the fluid to come back up that pipe, and it just needs to keep stuff out of the tank.

Now I just need to find a fancy wrench for the 5 gal TKS jugs.

[Rmnpilot]

7 minutes ago, milotron said:

I had this issue on mine when I first got it. I make a point of 'lubing' the threads with TKS when I fill it up. I didn't want to risk contaminating the TKS with any kind of lube or solvent.

I also don't crank it down hard, just barely hand tight. There is no way for the fluid to come back up that pipe, and it just needs to keep stuff out of the tank.

Now I just need to find a fancy wrench for the 5 gal TKS jugs.

I only tighten it enough to get the latch to close.   I’m honestly afraid I’ll rip the latch off regardless of installing or removing. 

[Fly Boomer]

2 hours ago, Rmnpilot said:

My TKS filler cap is beyond difficult to remove or install.  I saw a previous topic from 2017 where the recommendation was silicone spray, lithium grease or to replace.   Anyone have any updates?  I’m afraid I will rip the hinge off on the filler door.   It can’t be designed to be this difficult.  I’ve looked over the threads and while they are all designed as square, they aren’t in bad shape.  
 

Any chance the cap and the fitting it attaches to are contaminated with TKS fluid?  Maybe both parts need threads cleaned?  I would try a rag dampened with hot water.  I keep a hot pot in the hanger for jobs like this.  Hot water works great on bugs.

[Rmnpilot]

1 minute ago, Fly Boomer said:

Any chance the cap and the fitting it attaches to are contaminated with TKS fluid?  Maybe both parts need threads cleaned?

Tried that.  I cleaned both the female and the male.  Ran my finger around all of them.  No burrs.   I’ll mess with it more tomorrow as I’d like to fly but I can’t get the thing tightened enough to get the filler door closed now.   I may try some synthetic grease or o-ring lube.  Something plastic safe.   

[exM20K]

13 hours ago, milotron said:

I also don't crank it down hard, just barely hand tight. There is no way for the fluid to come back up that pipe, and it just needs to keep stuff out of the tank.

Actually, believe it or not, there is!

my fill tube had a droop in it, which trapped fluid just downstream of the filler.  In flight, the avionics bay develops sufficient low pressure relative to the vent-pressurized tank that fluid was drawn back up and out the pin hole on the filler neck.  There may also have been tank venting issues, but since that is a big pain to get at, we stopped work after removing the undesired p-trap with some zip ties cured the problem.

My cap is snug but doesn’t bind. @Rmnpilot I’d suggest you reach out to Mooney or CAV Aero.

-dan

[Fly Boomer]

15 minutes ago, exM20K said:

Actually, believe it or not, there is!

my fill tube had a droop in it, which trapped fluid just downstream of the filler.  In flight, the avionics bay develops sufficient low pressure relative to the vent-pressurized tank that fluid was drawn back up and out the pin hole on the filler neck.  There may also have been tank venting issues, but since that is a big pain to get at, we stopped work after removing the undesired p-trap with some zip ties cured the problem.

My cap is snug but doesn’t bind. @Rmnpilot I’d suggest you reach out to Mooney or CAV Aero.

-dan

Number I have for CAV is 913-738-5390 in Kansas City.

[Rmnpilot]

I talked with CAV this morning and waiting on pricing for a replacement cap assembly. I can see where someone prior to me needed to use a pliers of some sort to assist.   So I filled the tank up and now have the cap on.  I guess I’ll need to keep a channel lock in my plane for the time being.  First world problems I suppose. 

[ilovecornfields]

You can use an oil filter strap wrench like this one to get it off then make sure not to over tighten it next time. I found I was initially putting the cap on way too tight.

ARES 56034 - 2-Piece Rubber Strap Oil Filter Wrench Set - Adjustable Up to 4-inch and 6-inch Diameter - Non-Marring Slip Resistant Strap Wrench - Ergonomic TPR Handles 

[Rmnpilot]

I ended up ordering a new cap assembly.   The tks was installed over 20 years ago so who knows what’s happened with the cap over that span.  Filled the tank up with tks, tightened the cap until I was able to clear the door and will replace it when it comes in.   Fly safe!

[Fritz1]

same here, somebody had cross threaded my cap, replaced the whole assembly 3 years ago, smooth ever since

[Fly Boomer]

22 minutes ago, Fritz1 said:

same here, somebody had cross threaded my cap, replaced the whole assembly 3 years ago, smooth ever since

Never occurred to me that it could be cross threaded.  Sorry for your experience but, because you shared your experience, I'll be more careful.  I have a bad habit of over-tightening things.