Cut-off Solenoids Backing Out?

[whc03grady]

Just because, before undertaking a shortish trip I checked on the wiring between my carbs. When I felt for the connection at the left carb's cut-off solenoid, it basically spun around, it was so loose. I tightened it up by hand and then checked the right one, which also took some hand-tightening but wasn't nearly as loose as the left. It did, however, have gas on it; gas wasn't dripping off it, but gas had clearly leaked out onto it.

I'm a nervous type, so checking the tightness of the cut-off solenoids has since become a regular part of the pre-flight walkaround. And wouldn't you know it--they almost always need at least a little tightening!

Do I wrench them down with a wrench? Naturally I'm afraid of breaking something. But I'm also afraid of one liberating itself from the carb at speed, which I assume would quite likely lead to an impromptu bbq. And why would they be backing out anyway?

[Amskeptic]

Just because, before undertaking a shortish trip I checked on the wiring between my carbs. When I felt for the connection at the left carb's cut-off solenoid, it basically spun around, it was so loose. I tightened it up by hand and then checked the right one, which also took some hand-tightening but wasn't nearly as loose as the left. It did, however, have gas on it; gas wasn't dripping off it, but gas had clearly leaked out onto it.

I'm a nervous type, so checking the tightness of the cut-off solenoids has since become a regular part of the pre-flight walkaround. And wouldn't you know it--they almost always need at least a little tightening!

Do I wrench them down with a wrench? Naturally I'm afraid of breaking something. But I'm also afraid of one liberating itself from the carb at speed, which I assume would quite likely lead to an impromptu bbq. And why would they be backing out anyway?

Clean the threads on the cutoffs and the carb and try a little wrap of thread tape. Do not tighten more than by hand, it can act like an unwanted drill bit at the bottom of the hole and slowly choke off the fuel supply it is attempting to control.

They back out as indication of a slightly wallowed out hole + engine vibration. We want to be very nice to the threads in the carb.

What are your daytime temps up there right about now?
Colin

[whc03grady]

Clean the threads on the cutoffs and the carb and try a little wrap of thread tape. Do not tighten more than by hand, it can act like an unwanted drill bit at the bottom of the hole and slowly choke off the fuel supply it is attempting to control.

They back out as indication of a slightly wallowed out hole + engine vibration. We want to be very nice to the threads in the carb.

What are your daytime temps up there right about now?
Colin

You mean that teflon tape stuff, right?

Daytime temps are in the 50s, 40s.

[Amskeptic]

Clean the threads on the cutoffs and the carb and try a little wrap of thread tape. Do not tighten more than by hand, it can act like an unwanted drill bit at the bottom of the hole and slowly choke off the fuel supply it is attempting to control.

They back out as indication of a slightly wallowed out hole + engine vibration. We want to be very nice to the threads in the carb.

What are your daytime temps up there right about now?
Colin

You mean that teflon tape stuff, right?

Daytime temps are in the 50s, 40s.

Yes, the white teflon tape, not too much. Mark the position of the solenoids once snug with a black sharpie marker, visible at due horizontal when you look into the engine, and you will be able to see any migration. Cleanliness here will help prevent any bits of junk from making the engine's life miserable.
Colin

[satchmo]

Clean the threads on the cutoffs and the carb and try a little wrap of thread tape. Do not tighten more than by hand, it can act like an unwanted drill bit at the bottom of the hole and slowly choke off the fuel supply it is attempting to control.

They back out as indication of a slightly wallowed out hole + engine vibration. We want to be very nice to the threads in the carb.

What are your daytime temps up there right about now?
Colin

You mean that teflon tape stuff, right?

Daytime temps are in the 50s, 40s.

Yes, the white teflon tape, not too much. Mark the position of the solenoids once snug with a black sharpie marker, visible at due horizontal when you look into the engine, and you will be able to see any migration. Cleanliness here will help prevent any bits of junk from making the engine's life miserable.
Colin

Don't those solenoids need to have a ground path through the threads? Many of the solenoids I have seen have a good rubber collar/gasket that would prevent grounding from the body of the solenoid to the carb, and if you put teflon tape on the threads, that might cause a problem. Or am I over-thinking it?

Tim

[Amskeptic]

Don't those solenoids need to have a ground path through the threads? Many of the solenoids I have seen have a good rubber collar/gasket that would prevent grounding from the body of the solenoid to the carb, and if you put teflon tape on the threads, that might cause a problem. Or am I over-thinking it?

Tim

You might have a point there, Tim. I have seen teflon tape eat right through on the side of the threads that has to pull the solenoid inward, and provides an electrical path. The seat is also available for electrical flow, if it gets contacted. I am hoping that the "leeward side" will be filled with anti-back-out goop.

Mitch? Check for solid actuation by turning on the ignition and touching the wire terminal to the spade, good click? Do you have the little collars with the rubber seals?

[whc03grady]

Mitch? Check for solid actuation by turning on the ignition and touching the wire terminal to the spade, good click? Do you have the little collars with the rubber seals?

I assume you mean I should check this after I apply the teflon tape (very little, to the threads only)? Because, I have yet to do that.
At my next opportunity (likely not soon, as Winter has descended upon us here at 5,280' and 46.12 N) I will check for a collar, apply the tape, and confirm a click. Then repeat for the other carb. Is that right?

[RSorak 71Westy]

No tape the rubber collars should provide the seal, the solenoid needs a path to ground, which the tape may interfere with.

[Amskeptic]

No tape the rubber collars should provide the seal, the solenoid needs a path to ground, which the tape may interfere with.

I specifically mentioned for Mitch to test the solenoids for correct actuation with the teflon tape. Gotta experiment sometimes ...
I specified (!) teflon tape to help save the damn carb threads which wallow out every time those solenoids vibrate loose, rendering the carbs junk. It is the bane of dual carb buses, most usually with that heavy central cut-off plunger.

The teflon tape reply was in answer to Cut-off Solenoids Backing Out? The cut-offs are designed to seat at their snouts, you can see a beveled edge that would hopefully ensure the electrical path (along with the occasional grounding afforded by the aforementioned "windward" side of the threads.
My recommendation was suggested to fill the voids in between the thread grooves. Vibration is serious, and it will seriously help erode that cheap pot metal carb body.
Colin (!)

[whc03grady]

What about green Loctite?

[Amskeptic]

What about green Loctite?

Green Loctite could indeed be a useful sauce. But it is up to you to ensure that the solenoids click at your request before the stuff hardens up. Test test test.
ColinInAtlanta

[whc03grady]

Roger that. I assume you're implying the green Loctite is an irreversible procedure.

[Amskeptic]

Roger that. I assume you're implying the green Loctite is an irreversible procedure.

No, I am not "implying" any such thing. I am just asking that you ensure that there is an electrical path that WORKS before you blessedly get to forget about this annoying crap and perhaps enjoy some reliability. When you decide to remove the cut-offs, the green stuff splinters and releases its grip just fine.
Colin