Jaguar thermostat housing cap leaking

[alterego]

Hi,

Lincoln LS V8 Gen1
I got some overheating problems with leaking coolant from thermostat housing, figured out that problem is in bad hydraulic fan actuator(fan does not kick in high speed) and plastic coolant housing was deformed(leaking gap in connection). Just replaced plastic thermostat housing to jaguar aluminum, but did not put thermostat back, because i want to check it. I don't know if it is possible to correctly bleed air from system without thermostat inside, but i tried and got this.
https://youtu.be/H3LtxIleHfY

When i turn heater to max inside the car, coolant starts leaking from the thermostat housing cap. When i turn heater off it stops. Cap of thermostat housing has been replaced tight and not over-tightened.

What about the color of my atf fluid? Is it ok?

 

[joegr]

It looks like the seal on your cap is bad, or the neck of the thermostat housing is defective.
There's no good reason to not install the thermostat. Running without a thermostat won't stop it from overheating and it will cause additional engine wear.
You need the hydraulic fan system, and when you do you might as well replace as much of the fluid as you can. It looks okay in the picture.

 

[oddball]

I wasn't terribly impressed with the quality of those aluminum parts. Seems like they used a plastic one to make the mold.
Make sure the rubber seal is actually in the cap. The poorly cut threads are probably locking up before the seal actually hits the housing.
No specific advice, just work on it carefully to get it to seat well. Or find an additional rubber gasket to put on there to take up more space.

 

[Rapidtransit]

I had the same thing happen to me when I installed the aluminum thermostat housing.
Make sure you use a torque wrench to tighten the cap. They use a o-ring to seal the cap to the housing. Too much force will distort the o-ring and cause the leak.
The cap says to torque to 9nm which is equivalent to 80 inch/lbs or 6-7 ft/lbs.

 

[izzy]

I tightened the cap on my jag metal housing by hand. no issues.

 

[RigsLS]

JAG thermostat housing is/was best upgrade to my LS, zero issues.

 

[02LincLS]

.

 

[02LincLS]

I wasn't terribly impressed with the quality of those aluminum parts. Seems like they used a plastic one to make the mold.
Make sure the rubber seal is actually in the cap. The poorly cut threads are probably locking up before the seal actually hits the housing.
No specific advice, just work on it carefully to get it to seat well. Or find an additional rubber gasket to put on there to take up more space.

Agreed. Mine had a notch out of the sealing face. I had to use a palm sander to flatten it so that the rubber could contact the whole way around. Fortunately there were enough extra threads that it still bottomed on the rubber.