what sealant to use where black tank connects to dump plumbing?

[jackvosney]

Hello, I thought id ask here to see what is recommended to seal where black tank connects to dump plumbing? Ive attached a pic for reference.

Mine is leaking and its got some type of goupey sealant there now, maybe silicone, not sure.

[GCinSC2]

Jack,

I just filed my paperwork for my been there done that certificate for valve R&R on my 2007. Yes, I searched etc and saw several "recommendations".

I called my AS dealer / repair shop and talked to a life long AS tech and posed the same question.

Butyl rubber adhesive sealant.

It was no a common item no local hardware or home center had it. I did find it at an RV dealership.

Feel the clean part of the exposed sealant, feels like chewing gum?

Gary

[ROBERT CROSS]

I used 3M 4520 Marine.
Semi permanent and made for wet environment sealing.
I've used 3m 4200 & 5200 on the AS for many years with good results.👍

POI...trying to seal it from the outside will be problematic, If you want to try I would consider 3m Extreme Sealing tape.........From Amazon.


Bob
🇺🇸

[jackvosney]

Thanks Gary this is helpful. Did you separate the pipes and reseal? Or just apply new sealant to the outside?

Originally Posted by GCinSC2

Jack,

I just filed my paperwork for my been there done that certificate for valve R&R on my 2007. Yes, I searched etc and saw several "recommendations".

I called my AS dealer / repair shop and talked to a life long AS tech and posed the same question.

Butyl rubber adhesive sealant.

It was no a common item no local hardware or home center had it. I did find it at an RV dealership.

Feel the clean part of the exposed sealant, feels like chewing gum?

Gary

[jackvosney]

Thanks Bob! I assume when you say sealing the outside would be problematic your are saying the better option is to separate the connection and apply sealant inside the joint like you would standard ABS plumbing correct?

Originally Posted by ROBERT CROSS

I used 3M 4520 Marine.
Semi permanent and made for wet environment sealing.
I've used 3m 4200 & 5200 on the AS for many years with good results.👍

POI...trying to seal it from the outside will be problematic, If you want to try I would consider 3m Extreme Sealing tape.........From Amazon.


Bob
🇺🇸

[GCinSC2]

Jack,

In the R&R determined that one flange was not surviving. I wiggled the valve or for you looks like fitting and pulled, wiggled, pulled and it came out. If flange slip joint is reusable might be able to clean slip and tank and reinstall getting all lined up etc.

But hands on observations beat armchair guesses.

I let it cure overnight then filled with water and tested all joints etc.

Gary

[ChaseTrout]

Hello,
Interested to learn more about the actual product you purchased for this repair. While reaching under our rig this week I noticed the seal was broken around both the black and gray pipes where they entered the metal boxes holding the tanks. Looks like it just needs a bit of chaulk and maybe a result of the exterme cold weather this past winter. Appreciate if you still have the brand name or reccomendation from the AS tech.
Thank you,
Jim

[richard5933]

Applying sealant to the exterior of these would do nothing more than further aggravate the mess.

On my installation I used a very thin coating of Sikaflex between the plumbing and the tank's collar. Nothing more should be needed if the parts fit together properly without any debris or deformation of the plastic. The clamp is what provides the majority of the seal, and the sealant is there just to fill any gaps which might be remaining.

My advice if this is leaking is to pull the valves down from both tanks, replace the valves with new, and then do a clean reinstall of everything. It sounds much worse than it is in reality, other than having to work on your back. It looks like you already have access to your tanks/valves, and that's probably the most difficult part.