I think I found my coolant leak:

there's a cap on top of the thermostat housing (at least that's what I've seen it called elsewhere) that looks like it can be removed with a large Allen key. I observed small bubbles and coolant slowly bleeding past the threads (and some gooey thread sealant around the cap). This cap and housing appear to be plastic.

questions: Is this cap easily removed with an allen key? suggestions?
Is it only sealed with thread sealant or is there an o-ring I have to replace?

thanks in advance!

 

Replace thermostat with a metal one.

 

There is an o-ring. But the advice to replace with an aluminum tower is excellent. There is a lot of information on changing it on this forum if you are mechanically inclined. It would be wise to change the water pump and idler pulley at the same time. They are not expensive.
RJ
______________________
97 XK8 Aquamarine 85K mi

 

What about the chain tensioners? Are they the old plastic body type?

 

Finally replaced the plastic thermostat (cap broke off!) housing with the aluminum one. One caveat or issue I had: The housing cap with the allen key recess can have an issue sealing as well.

One, poor use of a o-ring to seal on the thin lip of the housing. The first time the cap was installed, the lip cut right into the o-ring, resulting in a leak. Two, the lip of the housing can be sharp from the aluminum casting.

Solution: Lightly sand the sharp edges of the OD and ID and replace the o-ring with a 0.070" - 0.1" thick rubber gasket. I cut mine by hand and used some silicon grease. No leaks! Finally no sweet smell of antifreeze when I get out of the car.

 

what type (mfg) of housing did you use. Wondering if the sharp lip is an issue on all of them?