Hartwig sells the Aux Tank cap seals for about $25/pair. They don't last very long - they compress quickly. I also have been using Fuel Lube on both the main and aux seals and it helps. I'll probably make my own next time.

Here’s a question for you guys with the newer gravity AUX tanks...

Do you get back flow into AUX tanks even though they have an in-line check valve between tanks? I do get back flow and I’ve talked to one other fella that did too and it bothered him. Can’t say it bothers me, but I’m just curious to hear from more folks.

Update on AUX caps.... got warranty replacements after about 4 weeks. Judging by looks of them, they’ve made some design changes. Old is the top cap and new is the bottom.

How much do the hartwig/monarch aux tanks add to the empty weight?

slow18 wrote:Here’s a question for you guys with the newer gravity AUX tanks...

Do you get back flow into AUX tanks even though they have an in-line check valve between tanks? I do get back flow and I’ve talked to one other fella that did too and it bothered him. Can’t say it bothers me, but I’m just curious to hear from more folks.

Update on AUX caps.... got warranty replacements after about 4 weeks. Judging by looks of them, they’ve made some design changes. Old is the top cap and new is the bottom.

The "check valve" is simply a piece of tubing with a hinged stainless steel "flapper" to cover the opening... They are pre-installed but if you look closely they do not fit tightly closed worth a crap.. I took them out of the set I installed, cleaned up the ends so that it was perfectly flat, re-bent the flapper so it would actually close flat against the tubes, re-installed them and they still back flow.. Really all they do is prevent huge sloshing of the tanks back and forth by slightly slowing the fuel down in that area.. Could be a better system though..

Brian.

Tanks are about 12 lbs each. Then just some interconnects and aux caps. No pumps or anything. I’d say about 26-28 lbs total.

It would be nice if they didn’t back fill when you filled the mains.

It would also be nice if they had a spot to install a sending unit.

Is there room enough to install a real check valve?

https://www.aircraftspruce.com/catalog/ ... kvalve.php

Perhaps, as long as they work in a low flow situation. The lines from aux to mains are 1” to 3/4” if I remember right, so it would need to be a big check.

Really, the only major downside is not knowing the fuel quantity in the aux tanks. Oh, and if you park on a slope while camping and don’t turn the fuel off, you end up with a REALLY heavy wing in the morning.

Seems like it wouldn’t be too hard to add a sending unit to a plastic tank, but I doubt there’s any certified options to do that.

Waiting on Mosaic….

Is there any update from anyone who's installed these monarch tanks in an early 180? Is there a separate filler neck? Do they connect to your mains, or is there an electro-digical transfer pumpinator you have deal with?

Is there any update from anyone who's installed these monarch tanks in an early 180?

I installed mine.

Is there a separate filler neck?

Yes

Do they connect to your mains?

Yes

Is there an electro-digical transfer pumpinator you have deal with?

No

Thank you, slow18. Was this recently?

slow18 wrote:Is there any update from anyone who's installed these monarch tanks in an early 180?

I installed mine.

Is there a separate filler neck?

Yes

Do they connect to your mains?

Yes

Is there an electro-digical transfer pumpinator you have deal with?

No

Have you talked to them? They were some health problems going on in the company and last I heard there was a huge waitlist because they didn’t have anyone to make them.

I think it was in 2018 give or take a year.

The wing-x website touts Monarch aux tanks:

https://www.wingxstol.com/html/other.html

but the Monarch / Hartwig website doesn't seem to show them:

https://www.hartwigfuelcell.com/monarchcaps.php

Plus, I heard some time ago that Monarch quit making the plastic (?) aux tanks for the early ("slant-tank") 180's
because there were a lot of problems with them not fitting.

They stopped making rigid slant main tanks. The rigid aux tanks are still made. No fitment issues noted.

It’s not a quick install.

Overall, I’m glad I did it, but there are aspects of it that I’m not a fan of. If you’re paying for labor, it might be smarter to just go find a set of later model wings already set up with long range main bladders. I think those give you around 84 gallons or so.