HTPerformance
New Member
Supersonicsvt From Focal Jet:
"For all you folks with SVTfs that leak coolant near at the thermostat housing area (if you don't have it now, you will!), here's what was wrong with mine - and how you can fix yours for $2 in 10 minutes.
There are two ports in the plastic thermostat housing that use a small O-ring to seal the port. One is the temperature sensor coming out of the top, and the other comes out of the bottom at a 45 degree angle - mine was just an aluminum plug. Mine was leaking at this plug whenever it got really cold. Some folks have leaks at the temperature sensor, same problem. Once hot, it didn't leak.
The problem is that Ford saved about $0.50 by using a Buna-N (Nitrile) O-ring to seal these ports . Buna-N is only good for a MAXIMUM 230°F service. The engine runs constantly at just about that temperature, and hotter when you shut down after a long run on a hot day. So after a few years, these O-rings get hard and don't seal.
So, rather than pay $60 for a thermostat housing, and/or $10 for a plug (or a fortune for the dealer to fix it, if he ever does), here is what you need to know:
You need a #203 O-ring, made out of VITON. Viton is good for 450° service."
For the lower plug, the #203 will work, and the #109 for the temperature sensor."
"For all you folks with SVTfs that leak coolant near at the thermostat housing area (if you don't have it now, you will!), here's what was wrong with mine - and how you can fix yours for $2 in 10 minutes.
There are two ports in the plastic thermostat housing that use a small O-ring to seal the port. One is the temperature sensor coming out of the top, and the other comes out of the bottom at a 45 degree angle - mine was just an aluminum plug. Mine was leaking at this plug whenever it got really cold. Some folks have leaks at the temperature sensor, same problem. Once hot, it didn't leak.
The problem is that Ford saved about $0.50 by using a Buna-N (Nitrile) O-ring to seal these ports . Buna-N is only good for a MAXIMUM 230°F service. The engine runs constantly at just about that temperature, and hotter when you shut down after a long run on a hot day. So after a few years, these O-rings get hard and don't seal.
So, rather than pay $60 for a thermostat housing, and/or $10 for a plug (or a fortune for the dealer to fix it, if he ever does), here is what you need to know:
You need a #203 O-ring, made out of VITON. Viton is good for 450° service."
For the lower plug, the #203 will work, and the #109 for the temperature sensor."
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