So I'm new here to the forum and actually built and have a totally different kind of vehicle.
I came across this thread in a search looking for help with cooling an Ecotec LNF.
Hope some of this might help anyone dealing with the same issues.
Copied form another forum I have a build thread in.
I have been dealing with inconsistent cooling from the beginning of this build.
When you bolt an adapter to the Ecotec you are forced to change the thermostat housing.
I chose to bolt the CBM housing to the motor and this housing deletes the thermostat all together.
CMB says they have sold thousands of them and nobody has temp issues, but I find that hard to believe on any engine without a thermostat.
So what did I do I added an external thermostat. It helped and worked ok, but would get some spikes in temp until the system was fully up to temp then the spikes were not as noticeable.
I tried different thermostats, along with drilling different size and number of holes in them. Some made it better, some worse.
Bleeding the air out of the system was always a pain in the ass and would take hours/days at time to get it all out.
I have searched many different boards and others all having the same issue.
I finally did a proof of concept and will work on machining a housing to incorporate the changes.
I took the CMB block off and machined a bypass slot in the block to allow the engine to internally bypass as originally designed.
Then I removed and bored the hose location to accept an screw together inline thermostat housing, then took a light cut on the housing for a press fit into the block.
Now a thermostat will reside near the original location and the original engine bypass works again.
I'm using a 180 deg thermostat with 1x 1/8" hole in it.
I cracked the top turbo cooling line loose and then filled the system.There was very little bleeding to have to do and it worked perfect.
The engine ran all day @195deg with no spikes like before.