Searching for glycol leak in Aldi system

DanSees
DanSees Member Posts: 52
in Heating/Plumbing & Winterizing
I have a glycol leak somewhere under my bed on the drivers side of a 2021 Tab 320S BD. I lost enough fluid that I am not circulating the fluid at this time. The floor is completely covered in this area with glycol & it has leaked out on to the ground. I have cleaned it but there is no definate place that is leaking. We had the heat working for 3 days on our recent trip, on the 4th day the Tab would not get warm. I looked under the bed and found fluid. I have no bulged hoses at any of the connections. I was wondering if I could fill the system with distilled water and run the Aldi just to heat it up to find the leak if it doesn't show with it cold & not running? I know the glycol is a mix is glycol & water.  But I don't want to do any more damage if the system must have glycol to operate. I won't leave the distilled water in the system just using it for troulbleshooting. 
2021 T@b 320S Boondock 
TV - 2008 Toyota FJ Cruiser
Retired aircraft mechanic from AA
2-3 several week trips per year & other trips we can squeeze inbetween our long trips.
Avid road bicycle rider. always carry a bike or 2 with us.

Comments

  • vhollow
    vhollow Member Posts: 97
    My understanding is that the glycol’s purpose is to prevent corrosion (the additives) and prevent freezing. I don’t see a problem with your plan. My own system leaked where the hoses connect to the expansion tank, but only when using it. Double clamping solved it.
  • AnOldUR
    AnOldUR Member Posts: 1,755
    Not sure, but guessing that the glycol also provides some lubrication for the pump. Thinking that even if this is true, short term for testing wouldn’t hurt. 
    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler
    60,865 camping miles through the end of 2025
  • ScottG
    ScottG Administrator Posts: 5,682
    I doubt the "boiler" temperature gets anywhere close to actual boiling. If I was in your situation I'd do exactly the same. Why pour in more glycol just to mop it up from the floor?
    2015 T@B Max S (320)
    2015 Nissan Frontier SV V6 4x4
  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,634
    Have you looked at the Auto Air Bleed Valve and the black hose from that valve?  Unless an aluminum stub end has completely deteriorated inside/under one of the hoses in the Alde compartment (there are several connections/connectors to look at closely) it could be the Auto Air Bleed valve is malfunctioning.  When the bleed valve sticks, the glycol that should flow through the valve instead gets "vented" out of the black hose on the side of the valve.  The black hose could have a leak, or...that black hose, instead of being firmly attached to the "grommet" or "plug" in the floor, is not secured in the little grommet.  A failed valve, trying to drop glycol out of the black tube could be the problem.
    Your idea of filling with distilled water, and then running the Alde pump on "continuous" will allow you to run the pump without the heat being on.  The glycol (or water) will circulate through the "loop" and you should be able to see almost immediately if the Auto Air Bleed Valve is faulty, or if one of the connections in the Alde area is having issues.
    Picture below shows the Alde compartment, with the "grommet" mentioned at "H".  
    I think there are about a couple of  different clamped "fittings" along the hoses, one for the check valve next to the Auto Air Bleed valve, and another where the drain fitting for the glycol goes out under the trailer.  If every thing else here checks out, you would probably need to fish back behind the bed and shelf, where there are several other clamped fittings.


    2017 Outback
    Towed by 2014 Touareg TDi
  • Pintoplumber
    Pintoplumber Member Posts: 182
    edited November 2025
    Have you looked at the radiation on the back wall? I have a leak where the rubber cracked and broke because of the bulge.

    2016 320 CS-S  1954 Ford F100  2017 Chevy suburban  2023 Chevy Silverado 1500
  • DanSees
    DanSees Member Posts: 52
    Thank you to everyone who commented here. These are some great suggestions. And thank you for confirmig what I thought I could do with distilled water. I am 99% positive there is no leak coming from the rear convector. Because that area is very dusty & dry with no streaks of any fluid running down that slanted wall. However I now have everything exposed & will confirm this. PT Thomas your suggestion of the auto bleeder makes alot of sense. I will post back when I get a chance to troubleshoot this leak. It may be a week or so, I have several other pressing things I must do prior to this & our camping season is now complete for a few months. 
    2021 T@b 320S Boondock 
    TV - 2008 Toyota FJ Cruiser
    Retired aircraft mechanic from AA
    2-3 several week trips per year & other trips we can squeeze inbetween our long trips.
    Avid road bicycle rider. always carry a bike or 2 with us.
  • DanSees
    DanSees Member Posts: 52
    I'm back, sorry it took so long to follow-up on this issue with the glycol leak. I've had some medical issues & then the freezing temps hit & I didn't want to leave distilled water in the system and have it freeze. Not knowing just how low the system was.
      I pumped in 3/4 gallon of distilled water till the return started returning fluid. Then about another quart. So my leak lost 3/4 of a gallon. I could not find a leak anywhere with the system static. I vigorously moved all the hoses & no leak. Next I turned on the Aldi and turned the pump to full and continuous, raised the temp to around 80' . The internal temp got to 162'. Again I moved all the hoses & fitting and still no leaks. I left the system on for 2 1/2 days. Still no leaks. I shut it off & left it alone for 5 more days & still no leaks. Today I drained out the diluted glycol + the extra gallon of distilled water I put in & serviced my Aldi with 2 1/2 gallons of Century fluid. Ran the system for a few hours after confirming all the pipes were getting hot. Still no leaks detected and I vigorously shook every hose, pipe fitting, pump, & valve in that area. My only thought would be maybe from the vent, but there is no cut in the hose from the vent to the outside. I'm at a loss & will send it down the road to our next camping trip. 
     We were at Approximately 22000 feet elavation. But we have been camped at 10,000 with no issues in the past.
      I have no clue where or how the glycol leaked out other than it was under the bed where all the hoses, pump & breather are. 
    2021 T@b 320S Boondock 
    TV - 2008 Toyota FJ Cruiser
    Retired aircraft mechanic from AA
    2-3 several week trips per year & other trips we can squeeze inbetween our long trips.
    Avid road bicycle rider. always carry a bike or 2 with us.
  • vhollow
    vhollow Member Posts: 97
    The areas where the corrosion was the worst on my 2018 400 were nearest to the return to the expansion tank: the convector under the bathroom and the line from there to the tank. Were you able to check there? Also, I have had leakage in the past at the clamps of the hoses on the expansion tank, not due to corrosion but because of the nipple design on the tank. A slow leak is hard to find. The fluid can be warm and evaporate. Good luck!
  • ColoradoSun
    ColoradoSun Member Posts: 136
    edited August 5

    I'm having a similar issue with the Alde glycol on our 2021 T@B 400. Five years no problems until this summer when I found the reservoir tank empty after a three day trip. I refilled it before another three day trip, checked it several times while camping but found it empty after returning. Refilled it again and checked it a few times in the following weeks. Initially it looked normal until today when it was empty again. The system had been off the entire time. No obvious sign of any leaking fluid around the Alde unit under the rear bed.

    2021 T@B 400 BD, 2020 Toyota Tacoma Double Cab
    SW Colorado
  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,634

    @ColoradoSun the Alde can drop glycol in a couple of spots: through the top of the Alde tank and out of the trailer through the tank's overflow tube. Or, it can lose it through the black hose coming from that large brass fitting on the side of the Alde. That is the Alde Auto Air Bleed valve. If that valve is stuck "closed", instead of the glycol circulating through the "loop" it will be ejected out of the trailer through that black hose. Follow the hose and you will find a "grommet" in the floor where the glycol will escape.

    The glycol is half distilled water. It is possible the glycol is evaporating the water out, but that is not definitely proven. How much glycol have you needed to add to bring the tank level up to "normal?"

    Did your Alde work normally on your trips?

    2017 Outback
    Towed by 2014 Touareg TDi

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