how hot is too hot??
 

Im finally finished with my engine swap putting the 3.3L into my 86 Vanagon - before yall hate the donor car was mostly junked -

im fine tuning the coolant system and its quite a doozey. the vanagon system is a sealed system - no radiator cap - and i think i might have a bad thermostat. if i have a bad thermostat i dont want to replace it until im absolutly positive its the problem

im curious as to normal operating block temperatures for the svx. im planning on getting a laser thermometer to make sure i dont overheat the block while i test the system. so far its been getting what seems very hot very fast - my fears are that ive got an air bubble somewhere in the motor...

Re: how hot is too hot??
 

If there is a bubble or you assume there is best to attempt to get rid of it. I believe the the operating temp is somewhere near 200 212 so anything above that and you are asking for trouble I hope you find out and don't destroy the block in the process.

Re: how hot is too hot??
 

The sealed system must have a pressure relief valve in lieu of the normal pressure radiator cap. The boiling point of the fluid is fixed as a result of the maximum working pressure set by the valve. Investigate accordingly.;)

Re: how hot is too hot??
 

I believe on the 3.0 H6 and maybe the 3.3 also there is a trick about raising the front of the car and running the motor to free a trapped air bubble when replacing the coolant.

Perhaps ask YT or OT.