Greetings,
I have been having trouble with air getting trapped in the cooling system of my stock 89 Turbo caravan. This last time I replaced the thermostat, I did not drill the hole in the thermostat, figuring I might get some hotter heat with the stock way of doing the thermostat.

I don't suspect the head gasket because the oil is clean and the antifreeze is clean, no white smoke and it runs well. However, I do notice some evidence of antifreeze leaks. The little bypass valve for the heater core has a tiny leak, and the rubber hose connecting the cooling line from the turbo to the thermostat housing (the one that is metal and once had a rubber hose crimped on) has a rubber hose with hose clamps. This rubber hose looks bulged and possibly leaky.

Question is, even if I replace these parts, will that 1/16" or 1/8" (can't remember size) hole in the thermostat solve the problem? Or should I be more concerned about why the air is getting into the system in the first place?
Thanks,
Lee