Help identify mysterious driveway puddles... clear, odorless, slightly viscous

[pw1981]

Yesterday, there was a fairly sizable puddle coming out from under my Expedition while it was parked all day. Its backed into the driveway, which means it's inclined forward a few degrees. The leak ran from under the truck, out a couple of feet. I attached a photo of that puddle, but I had backed the truck up a couple feet to get a better look at it. The driveway surface was wet to the touch, but the liquid was colorless, had no detectable odor, and had a very slight oily/viscous feel rubbing my fingers together.

I left it parked all day today, backed slightly further up in the driveway to see if there was any additional. Indeed, there is another puddle. Same clear substance, originating from the same general area under the truck. I attached photos of where the puddle is without moving the truck this time.

I went under the truck, over the truck, looked all around the lines in the engine bay. I cannot find anything that is 'wet' other than the driveway. I see no seeping lines or hoses. The shields and crossmembers seem dry to me. No loose clamps. The engine starts, stops, runs, and sounds completely normal. The AC system seems to be functioning perfectly fine.

I am really at a loss here. I am hesitant to drive the truck on my days off (tomorrow and Thursday) without some idea what I am dealing with. I have a service appointment on Friday to address a recall notice and I already added this to the list for them to check, but like I said, I have errands I need to run and I am hoping the brainpower here has some ideas what I am dealing with so I know if it's safe to drive - I certainly don't want to damage anything.

Images:
7191 - Last night, full puddle
7198 - Today, remnants of last night visible with the new one underneath
7199 - Under truck, today's puddle
7202 - Also under truck today

 

[Trainmaster]

If it dries up and leaves no significant stain can it be condensation from the air conditioning? If it were brake fluid it would taste nasty, be very oily and stain concrete. And you'd get a brake light with that leak. Compressor oil from the air conditioning also would stain.

You don't say how old your truck is, but it could be trapped water from a body panel and the oil could be coming from the metal's factory finish.

 

[pw1981]

If it dries up and leaves no significant stain can it be condensation from the air conditioning? If it were brake fluid it would taste nasty, be very oily and stain concrete. And you'd get a brake light with that leak. Compressor oil from the air conditioning also would stain.

You don't say how old your truck is, but it could be trapped water from a body panel and the oil could be coming from the metal's factory finish.

The truck is a 2018 Limited with 61k on it. You can sort of see the drying stain from the first day in the picture of the second. It does not appear to be a stain, but it certainly is taking its sweet time drying. It has not rained in a number of days.

I am with you on the not being brake fluid and if the compressor lost that much oil it would seize for sure. Haven't really run the AC in a few days given that its been 30-50 degrees here in Florida so I have been using the heat, which is a rare occurrence. But I ran it on max for 15 mins or so and it seemed ok. I don't think its AC condensate, because that wouldn't still be visible after 24+ hours.

One thing I hadn't considered is the possibility that it's just general condensation from the engine compartment? It was 30 degrees outside and I parked it hot. Then given that its a black truck, once the sun comes out, it cold just be 'sweat' from the engine compartment. This could account for the slight oily texture from the various surfaces? Just throwing that idea out.

 

[Zig10]

Did you check the struts (if yours is non CCD)? When one of mine leaked it dropped what looked like a cup onto the ground. The other two just dripped all over the frame.

 

[Soliyou]

This seems like a coolant leak. Check the coolant level to confirm. This amount of leakage should leave the coolant close to minimum in the reservoir.

 

[pw1981]

This seems like a coolant leak. Check the coolant level to confirm. This amount of leakage should leave the coolant close to minimum in the reservoir.

I think you are correct. The reservoir was not low last night when I checked - about mid way between the MIN and MAX markings. But this morning I had another puddle and the reservoir was bone dry.

I topped off the coolant and slid a plastic bin under the truck to catch whatever is leaking. Hopefully this will determine once and for all what it is. I cannot imagine what would cause a random coolant leak, but we shall see. If that is what's happening, I will let the dealer pressurize the system and find it. I have Premium Care so its not really worth my time to try and fix it. I just want to make sure its safe to drive, so if just topping off the coolant is all I need to do then that's fine for a couple days.

 

[NukeLife]

It’s safe.

I have had two coolant leaks about a year apart. I got to where I was driving around with spare jugs of antifreeze in my cargo area. In a 2 year old $82,000 vehicle.

The first time it was leaking at the coolant line fitting going into the driver side turbo.

The second time it was leaking around the water pump shaft seal. And this was on a water pump that had already been replaced once.

Quality is job 1.

 

[fatgroundhog]

I'm dealing with this now myself. But I'm out of warranty (105K), so I'll either find a way to fix myself, or live with topping it off.

 

[JExpedition07]

When cold your degas bottle for the cooling system will read a lot lower than when it’s hot. You need to compare it hot or dead cold.

 

[TM_Bob]

I had a similar issue with my 2019 Expe. My puddle was smaller that yours but seems to otherwise match your description. It turned out to be front shock fluid which I did not recognize as such. I did not notice a failing shock issue driving. Had it fixed under warranty.