Brown Liquid Rear Passenger Side

[FWGERHART]

Recently I noticed a brown color liquid on my RV pad under the coach, rear passenger side. Directly to the rear of the mud flap. The liquid doesn’t have an odor or feel (viscosity). Seems like colored water. I notice it’s wet after a rain storm. No rain no wet. I run the engine in idle mode for 30 minutes. No drip. Nothing wet on the pad. I recently had the stop light come on while idling. I added coolant and have not seen the stop light since. Is this possibly a radiator leak? 

Edited November 21, 2021 by FWGERHART
Added photo

[1nolaguy]

My guess it's likely rusty water. Add a few drops of phosphoric acid (fust inhibitor sold at most hardware stores- usually a green liquid thin a warter, not royal gelly). If it turns black or black particles precipitate out its rust, possibly carried by rain run off. BTW- PA is great to have around for treating anything that is rusty - tools, pipe, chassis, etc.

[FWGERHART]

13 minutes ago, 1nolaguy said:

My guess it's likely rusty water. Add a few drops of phosphoric acid (fust inhibitor sold at most hardware stores- usually a green liquid thin a warter, not royal gelly). If it turns black or black particles precipitate out its rust, possibly carried by rain run off. BTW- PA is great to have around for treating anything that is rusty - tools, pipe, chassis, etc.

So you think this is simply rusty chassis? 

[hex_nut]

That is what water drips look like after the water seeps down through a laminated wall and becomes stained from dissolved adhesives ( I think you understand how I know that).  I would be looking up above for water intrusion issues.

Richard

[Dear LaserWorks]

41 minutes ago, hex_nut said:

That is what water drips look like after the water seeps down through a laminated wall and becomes stained from dissolved adhesives ( I think you understand how I know that).  I would be looking up above for water intrusion issues.

Richard

That's what I was thinking.

[jacwjames]

49 minutes ago, hex_nut said:

That is what water drips look like after the water seeps down through a laminated wall and becomes stained from dissolved adhesives ( I think you understand how I know that).  I would be looking up above for water intrusion issues.

Richard

Yup, ask me how I know. 

Start at the beltline on top, I had a spot where the back cap met the top.  There was a wave in the fiberglass and the beltline did not seal correctly, probably prone to flex movement. 

I stripped out all the old beltline and cleaned it all good and used Geoflex.  Takes a little time but I taped everything before caulking, wet my finger to smooth out the Geoflex and then pulled the tape.  This provided for a smooth finish. 

[1nolaguy]

Replies above are all valid. Test it to see If rust but look for potential leak or seepage as well. Better to deal with that now than desalination later.