Hi all... running out of ideas, lol
Got the 850R back from mechanic.. Still same problem, car overheats and coolant blows out the expansion tank. What I've noticed is its not sending hot coolant into radiator bypass.. or not enough.
So far replaced radiator, coolant tank and cap, checked thermo fans, water pump replaced, system flushed and treated with sealtite (in case of crack in head, no change), pressure tested overnight.. No change. Thermostat changed too..
Anyone else had this happen? And what thermostat are you running? Not ready to pull it apart to check head just yet
Cheers
Dave

Ps... love this car.. Need to get back on road!

 

I'm damn near positive that you have a blown head gasket. I had the same issue and symptoms recently. Do a compression test and that will point you in the right direction. Do you have any white smoke coming out of the tailpipe? Also, if it overheated even slightly you will want to get the head checked for warpage.....

 

+1 for the head gasket. I had the same symptoms a couple of months ago.