unit91

Running without thermostat. Temp gauge stays a little to the left of center. Will lack of a thermostat hurt the engine?

2+2GT

Yep. It will take too long to warm up, and never get warm enough in cold weather. This will reduce mileage and performance, and create corrosion and sludge. Ford designed this engine to run at 190°. I prefer the genuine Ford unit with the air bleed to help with filling the coolant.

rbrown22

You need a thermostat! The water will flow to fast without it.

RHuckster

The colder you run the engine the more carbon build up, run a 180 minimum.

Rick

longlive289s

ya like 2+2 said. no major damage but youll never gain anything good from it.....why are you running with out a thermo?

jimmy428

my 69 coronet 500 was without a thermostat and ran hot as f**k. i put a 165 in it and runs perfect.