I have been working for the past 6 months getting my '68 Donzi 18 back on the water. I replaced lots of parts including the water pump impeller. All new gauges, sending units, wire harness from dash to engine and all new connections. Now when I run the engine I can't get the engine temp over 100 to 110*. I replaced the thermostat... no difference... I replaced the gauge .... no difference. I removed the sender and put it in a pot of boiling water, grounded the pot to the block and the gauge showed it and the sending unit are working.
I'm stumped. Any ideas?