[cygnus49]

My T-housing cracked at the bolt flange. So I bought an after market replacement which leaked so I ordered a Motorcraft part - still leaks even without any pressure applied.

An o-ring sits under the t-stat flange and gets compressed in one half of the housing by the rounded/cambered mating piece of the other housing half when bolted together. That means the t-stat is sealed but the mating piece is metal-on-metal?

Any help getting this one right is greatly appreciated.

[RandyStinchcomb]

iirc the o-ring sits on top of the thermostat and since you've had the coolant systen opened up, dont forget to fill it at the coolant X-over and not the DeGas bottle to avoid air pockets and an over heating issue

[cygnus49]

Thanks Randy - I had a choice since I apparently forgot what order the parts came off. Simple as it might be with only a few parts it didn't appear to be reasonable that the rounded mating piece doing the compression would sit on the o-ring (rather than the o-ring under the t-stat flange) but then as I brightly observed that makes a metal=to=metal fit (not good for liquids). The way you describe (if the o-ring stays centered while tightening) it forms a seal between the two in that space.

[cygnus49]

Originally Posted by RandyStinchcomb

....since you've had the coolant system opened up, don't forget to fill it at the coolant X-over and not the DeGas bottle to avoid air pockets and an over heating issue

Hi again Randy - so far so good. I've seen posts on 4-valves and overheating issues related to the x-over - how do you suggest I do the refill?

It would really help if someone knows of a reliable manual at reasonable cost (not subscribing to alldata etc).

[Lopez16]

Originally Posted by cygnus49

Hi again Randy - so far so good. I've seen posts on 4-valves and overheating issues related to the x-over - how do you suggest I do the refill?

It would really help if someone knows of a reliable manual at reasonable cost (not subscribing to alldata etc).

Ok I have a 98 Cobra and the manual coolant refill instructions are these:
Fill At the coolant fill tube plug(the one with the hex typeScrew located on black tube in front of fans, it runs across and screw is in middle) Reinstall fill screw plug when coolant reservior is full. After pressure cap and fill screw plug are installed put heater and ac, fan speed settings to high. Start engine and allow to idle for a couple minutes. You should feel hot air if it's cold turn off asap and try again.That's all folks.

[cygnus49]

Lopez and Randy thanks guys. As I am new to my SVT it takes a bit of thinking (OK maybe not my strongest suit).

[RandyStinchcomb]

no problem glad to hear it all worked out for you......
now on the shop manuals, I can get the Ford books but they are $$$