Leaking Coolant (pic) | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Leaking Coolant (pic)


Well-Known Member
May 19, 2006
Reaction score
City, State
Oceanside, CA
Year, Model & Trim Level
1998 Eddie Bauer 5.0
Well I just replaced my thermostat housing gasket as there was a puddle of coolant dripping from under there. That did not fix that leak, as there is still a small puddle forming directly under the thermostat housing. Well, thats one thing.

But today I came home and found this beauty underneath my passenger side behind the RF wheel. My coolant reservoir is already empty (was full yesterday). Heater core? Im going to crawl up under and look around in a bit, thought Id post this here first. 98 5.0 2WD. Thoughts on this?:


Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

Ok, well - Im confused...maybe it's not coolant? I got up under my truck and it appears that its just water thats coming out. I pulled away my RF inner fenderwell liner and saw this. The water is coming out of this black hub, but Im not quite sure what it is. Air Conditioner related? The water leaking out has no coolant in it, but my reservoir is dry for whatever reason


ya that is where my a/c condensation used to drip down on my 2000

Ya its just pouring out pretty good that is what is tripping me out, and its just water not coolant. I have no idea whats happening, because the coolant reservoir box is empty now too...not sure if it drained from there or what

if you didn't get all the air out of your cooling system when you refilled it, it will suck up the resevoir when it cools down. Put more in and keep an eye on it for a couple days. Have you been using the a/c? - looks like condensate. Man that thing is clean, no dirt, no rust - must be nice, everything here gets nasty in a hurry.

Will do thanks. Combination of always smelling antifreeze because of thermostat area, water leaking out the bottom of the truck, and the reservoir running empty, just paranoid I guess. Already replaced radiator and several hoses in last few months.

Alright well just in case somebody finds this post in a search down the road:

- As for the thermostat housing area leak - I took my truck in and had the cooling system compression test done, and the only leak they found was under the thermostat housing. Turns out I did not prep the backside of the thermostat housing and the front side of the intake manifold properly. I got a new gasket, went home, took it all apart again and sanded both sides down, then put the new gasket on. I have not had a leak since, seems to be working fine now.

- As for the massive water leak, me and the mechanic figured that some water condensation from the A/C built up and got clogged, then all poured out at once, or something, as there is no coolant leak in that area, and my heater is working fine so no heater core issue.

So just like that my Explorer is back in the game, maybe I will move forward with lifting it, etc haha.

Moral of the story, clean both sides before placing in new gasket :)

Is there a drain tube for the condensate tub? My mother had a similar problem last summer and I found there plugged drain tube (slime and dust) that allowed the resevior to fill up and leak both on the passenger side carpet as well as underneath near the firewall. Her vehicle is a Saturn, but still could be a similar issue.

Well, thats interesting. I took my truck for a spin around the block this morning just to make sure I am not leaking coolant from the thermostat area.

I parked my truck, and there is a small puddle of coolant directly under the thermostat area, but its not bad. Still sucks, will continue to monitor it. It must be a real finicky deal to get the new gasket to seal just right, already done this twice now...unless the lower intake manifold itself is leaking. I hope its just the gasket

I would put money on the timing cover gasket. Very common on 5.0s not long after a water pump replacement.

Also did you change the hose clamps to screw ones? The self tightening ones loose their spring after awhile and that little hose on the thermostat housing will leak.

If anybody is curious, I ended up getting another gasket and some RTV sealant and redid the job, haven't had a leak since.

Dry is good... :)

Thanks for posting the updates, K$- helps when people are searching for solutions. :thumbsup:

If anybody is curious, I ended up getting another gasket and some RTV sealant and redid the job, haven't had a leak since.

I'll be giving this a try. Mines been doing it going on a couple years and if it's that simple that would be great. It's looses such a small amount no one can pinpoint it but the smell gives it away.

No prob guys. The key is to put the RTV Sealant on the Thermostat housing itself (with the thermostat in place), then put the gasket on the housing, on top of the thermostat.

Next put the RTV on the other side of the gasket that is stuck to the housing. Then slide the (2) bolts through the housing and install it back on the manifold.

- I used my finger to spread the RTV sealent. I made sure it was covered on there good.

- Make sure to put the thermostat in place first, THEN put the gasket on top of it. Obviously make sure the spring part of thermostat is always facing the manifold when you install it. (It's easy to overlook these things on a seemingly simple task)