Ok. I thought it was a bad water pump leaking anti freeze... But I think it's gotta be the thermostat housing. Cause coolant is behind it. Can I change out the o ring without having to remove the whole water pump?

 

Yup, three 10mm bolts and the whole thing lifts off the top. It may be a bad thermostat neck though. They've been known to warp and not seal properly. The best bet is either a new neck or a reinforcing ring from somewhere (eBay).

 

Mine leaked after a coolant change. Swapped in a new square oring and it did the same.

The following fixed it and hasn't been a problem since. The ring is the same cost as a new housing.

Thermostat Housing Ring

 

I got one of those rings too, that's the way to go because of the even distribution of the pressure from the bolts to stop warping and leaks.

 

I just used a torque wrench to install the bolts to the specified torque. It seems to me that the pressure is pretty even that way. No leaks so far.

 

The problem is that if the person before you didn't use a torque wrench and just tightened away at the bolts, then the housing is likely warped and crooked and won't seal until it is straightened. Also, a lot of these things get rusty and pitted where they meet the o-ring seal around the thermostat and then they don't seal unless they're overtightened, which again, warps the housing. The reinforcing ring is the best way to go if you can't get the housing to seal up. The trouble is that you won't know you can't get it to seal until it is too late and then you're stuck waiting a couple days for the ring to get there. It's either that, or a custom aftermarket neck with a heavier flange on it...

 

When you pull it switch the bolts out to socket headed cap screws.

You'll have to go down to the hardware to get them, but they are easier to torque and not weak *** **** metal that breaks easy, so you can get an even torque on them.

In all honesty, I RTV'ed mine down.

 

Well should I go ahead and buy a 203 thermostat and new housing?
I found this website The new thermostat abd o ring from ford costs $33

http://www.dieselsite.com/dieselsite203thermostat.aspx

http://www.dieselsite.com/oemthermos...ordpsd73l.aspx

 

I had to replace my housing, anyway.