This past week I went on a trip with my wife from MN to Utah. Before we left I noticed the Coolant reservoir tank was super low, but no noticeable leaks, so I topped it off and we went on our way.

We stopped halfway at Mount Rushmore. When getting out of my truck, I smelled antifreeze, looked under the truck and still no leaks. I checked the engine when we got back from walking around for an hour and the reservoir tank was bone dry. Filled it up with water (all I had at the time) and drove to the nearest auto parts store about 50 miles away (while keeping an eye on the temp sensor - never got above halfway).

The very moment I pulled onto the street of the auto parts store, the temp gauge started to rise slowly. As I parked and shut the engine off, steam slowly started coming from under the hood (see picture #1 below to see from where), where the thermostat/housing is.


Filled up the the radiator and reservoir tank with coolant, radiator fluid leaking from below (see picture below), take it to a mechanic and he says it's probably the gasket and would be good to replace the thermostat and gasket. Also says we would be fine driving it the rest of our trip while periodically replenishing the radiator with water along the way and fixing it when we get home.

(Leak from underneath the engine)


So we drive the 500 miles to Utah, stopping about every hour to fill up the radiator with water (keeping an eye on the temp gauge- never letting it get higher than a little over half).

Get home, replaced the thermostat, thermostat gasket, and replaced the water outlet/thermostat cap (as the other one was a little chipped).

Flushed the radiator with radiator cleaner, water, then put in new coolant.

**my current issue**

Only while the car is running, does the radiator drip/leak coolant from underneath the engine (see previous picture to the exact point where it's leaking from). It leaked quite a bit before I fixed it, now it's about a drip every 5-10 seconds.

I am just at a loss as to what I need to replace? A certain gasket? Should I just cut my losses and bring it in to fix? I'm pretty mechanically savvy and would rather do it on my own but just looking for a permanent solution.

 

Welcome to the forum


Coolant leaks are pretty hard to ID since they can squirt coolant to another location and that's were you "see the leak" but not where the leak is, lol.

Especially if it only leaks after warm up/under pressure

Good look here at common leak point on the 4.0l SOHC engines: How To Replace the Upper and Lower Thermostat Housing on a Ford 4.0L V6 SOHC Engine

May not be this but good chance of it, did you replace the lower housing?

What I often do on hidden leaks is to rent a cooling system pressure tester
These connect to rad cap opening and have a manual pump and pressure gauge to pump up pressure in COLD system to 20-25psi
Then you can safely feel around to locate a leak

 

Thanks for the posts on V6~4.0L~SOHC engines & TStat housings; good reference info.
Replaced the old leaking FRPlastic TStat Housing with a new Aluminum TStat Housing
in 2019Aug on a 2001 Ford ExSportTrac; no leaks as of 2020Mar after ~5K more miles.
My full write up with pics on that repair:
http://2001fordexplorersporttrac.fandom.com/Coolant_ThermoStat_Housing