06 thermostat outlet housing kit and overheating

[Lava]

In July my coolant outlet housing (big chunk o plastic behind the thermostat) sprang a leak on the way home. RockAutoed a Gates CO34838 Coolant Outlet kit which includes the full front and back housing with a new thermostat. Swapped it out and spent two days trying to get the system to bleed correctly. I followed the bleed procedure over and over, and every time I thought I had it as soon as I would take it out on the road it would start overheating within a few blocks. I've swapped all of the plastic cooling system components at least once since I have had her (some parts multiple times) so I'm pretty familiar with the process, but never had this much trouble before. I thought for sure I had a crack somewhere else, but on a whim I swapped back in the front plastic piece of the housing that contains the thermostat from the old housing, and that took care of it instantly. I've put a several hundred miles on it since then with no issue. I'm not 100% sure the new thermostat was the issue. What I'm wondering is if what may have happened is there was still air in the block which acted as a buffer and never caused the thermostat to open? I've read recently that some folks (other cars) will drill a very small hole in the thermostat to allow water to flow through to help the bleed process. Has anyone had success doing this on their LS thermostat?

 

[rgorke]

In July my coolant outlet housing (big chunk o plastic behind the thermostat) sprang a leak on the way home. RockAutoed a Gates CO34838 Coolant Outlet kit which includes the full front and back housing with a new thermostat. Swapped it out and spent two days trying to get the system to bleed correctly. I followed the bleed procedure over and over, and every time I thought I had it as soon as I would take it out on the road it would start overheating within a few blocks. I've swapped all of the plastic cooling system components at least once since I have had her (some parts multiple times) so I'm pretty familiar with the process, but never had this much trouble before. I thought for sure I had a crack somewhere else, but on a whim I swapped back in the front plastic piece of the housing that contains the thermostat from the old housing, and that took care of it instantly. I've put a several hundred miles on it since then with no issue. I'm not 100% sure the new thermostat was the issue. What I'm wondering is if what may have happened is there was still air in the block which acted as a buffer and never caused the thermostat to open? I've read recently that some folks (other cars) will drill a very small hole in the thermostat to allow water to flow through to help the bleed process. Has anyone had success doing this on their LS thermostat?

All cooling parts HAVE to be Motorcraft. Aftermarket parts just won't work properly. I had a similar issue until I put in a new Motorcraft thermostat.

There are lots and lots of threads on this!

 

[joegr]

...What I'm wondering is if what may have happened is there was still air in the block which acted as a buffer and never caused the thermostat to open? I've read recently that some folks (other cars) will drill a very small hole in the thermostat to allow water to flow through to help the bleed process. Has anyone had success doing this on their LS thermostat?

No, that's not it. There's no need to drill a hole. There's already a bleed/bypass path. The Dorman thermostat is well known to be a problem.