Mystery overheating

[cycleguy55]

As you didn't have these problems prior to draining and re-filling the system, it would seem the most likely culprit is air in the system. Obviously the expansion tank is to aid in that, but if the air is not getting past the thermostat the best expansion tank in the world won't help.

I'm running a BBF, not an FE, but it was recommended that I drill holes in the thermostat plate to allow air to pass. My 180° thermostat has a 'jiggle valve' in it to allow air to pass, but I still drilled a pair of 3/16" holes in the plate and I've never had any cooling problems.

I suppose another possibility is a stuck thermostat, but it would be odd for the original 180° thermostat to work fine before you removed it, then fail when you put it back in. It would immediately overheat if it was in backwards, but it sounds like you've done these more than once so that's highly unlikely.

Your switch that turns on your fans is in the lower / return radiator hose. Is it possible the process of draining and re-filling your system dislodged something and you have a radiator blockage? If so, or at least to rule it out, a reverse flushing of the radiator may be in order.

Maybe this helps, or perhaps not. Best wishes on solving this!

[BAsque1]

Originally Posted by cycleguy55

As you didn't have these problems prior to draining and re-filling the system, it would seem the most likely culprit is air in the system. Obviously the expansion tank is to aid in that, but if the air is not getting past the thermostat the best expansion tank in the world won't help.

I'm running a BBF, not an FE, but it was recommended that I drill holes in the thermostat plate to allow air to pass. My 180° thermostat has a 'jiggle valve' in it to allow air to pass, but I still drilled a pair of 3/16" holes in the plate and I've never had any cooling problems.

I suppose another possibility is a stuck thermostat, but it would be odd for the original 180° thermostat to work fine before you removed it, then fail when you put it back in. It would immediately overheat if it was in backwards, but it sounds like you've done these more than once so that's highly unlikely.

Your switch that turns on your fans is in the lower / return radiator hose. Is it possible the process of draining and re-filling your system dislodged something and you have a radiator blockage? If so, or at least to rule it out, a reverse flushing of the radiator may be in order.

Maybe this helps, or perhaps not. Best wishes on solving this!

Well we did purged the system, and after it cooled off I topped it with more coolant the next day. The thermostat is in right not backward I will try running the car again with the cap off just in case that ther is still more air trapped in the system.
tks
Lou

[DanEC]

If you pull the thermostat again, you might drill a 1/8 inch hole in the flange and position it up when you reinstall the thermostat. That can help letting some of the air bleed out to the tank.