Antifreeze puddle on top of the engine - what else besides thermostat housing ?

[Explorer_PL]

First I smelled something, so I look under the hood, and on top of the motor under the intake manifold valley I see a green puddle of antifreeze. The thermostat housing looks new, it's plastic, I went with my fingers around and it was not wet so not sure if that's coming from that.

I think I see a freeze plug on top of the block ?
Where else could it be coming from ?

2007 4.0 v6

 

[07EddyB]

Could be a pin hole in a hose so don't just check the connections - check the entire hose.

 

[michael loibl]

Hose it down thoroughly and blow it dry with compressed air or even a leaf blower. After all traces of moisture are gone, get a pressure tester on it and study it from all angles with a good flashlight.
I just recently resolved a leak on my 06 4.0L. I knew my radiator (number 3) had a tiny pinhole leak, but suddenly I was finding a 6 inch diameter circle of wet under the car every morning, and my accessory belt was chirping like crazy.
I could see traces of cool and running down the front of the block near the crank pulley and was fearing it was the water pump. After removing the accessory belt to get a better view on the front of the motor, I could see a slight drip at the base of the plastic thermostat housing where the short bypass hose attaches. I replace the housing and the hose three years ago, and replaced the clamp with the Screw type. I’m not sure why it took three years to start dripping from that connection, but I tightened it a bit more cleaned it up and no more leak.

 

[MotorCityFats13]

mine does this from time to time even though the housing is not split the 3 bolts that hold it down to the intake decide to get loose..... and then they always take another 1/4 to 1/2 turn and leak stops for a few months....... I think I need to make friends with some thread lock in the future

 

[michael loibl]

I used a tiny dab of thread locker on each bolt when I did the housing 3 years ago, and never needed to tighten. I just apparently failed to sufficiently tighten the one clamp, but wired how it didn’t start leaking for 3 years

 

[Mitchs07explorer]

I would run the engine until full temp have someone fluctuate the rpm's then look at and around the thermostat housing and water pump just under the housing. My guess would be that it's still most likely the housing, that molded plastic can easily have cracks at the seams and you'd never be able to see it. When my thermostat housing started to go and I had a pool of coolant on top of my engine there was no visible evidence on the thermostat housing at first. Sure enough as time went by it became much more obvious. Save yourself the trouble and replace your housing. I would definitely recommend going motorcraft or also there is a steel after market version available. I ordered a complete dorman housing for $44 from Amazon. I immediately returned it once I saw the poor quality and the numerous reviews about Explorers starting to leak 3 months after they installed the cheap part. Trust me go motorcraft or better on this fix. Also make sure you use a torque wrench when tightening the bolts back in place, very easy to overtighten these things and create stress points.

 

[Explorer_PL]

That's my guess too - the housing again.

The metal ones go for $ 150 ????

 

[Davidm53]

I have the metal housing also. Have had the o ring leak on the sensor.
Took a few tries to repair it but it’s been holding a long time now.

 

[swshawaii]

This "may" be a less expensive option for an aluminum housing. Austekk has two different models. One has two sensor ports, the other has one. PM Austekk through eBay, they may offer the one sensor with the correct upper for your 2007 4.0L. Motorcraft RT-1220 is a new aluminum housing that may also fit but it's more expensive. Good luck!

bfoot58 | eBay