thetasig28

Just purchased 68' with the 327 350hp 4spd. After driving for 20 minutes in warm weather 78 deg. guage on the inside reads 210....
when i shut the car off, the coolant dumps out the overflow tube onto the ground. Ran the car for 20 min sitting with the cap off the tank, thought maybe air lock. heated up to 215, shut the car off, coolant instantly boiled over.
Thoughts?

Sidepiper

Welcome,

Try giving the system a good flush, replace the thermostat. Maybe the car had sat for awhile before you purchased it.

Roughrider

Good advice. Consider replacing all the hoses as well if you don't know how old they are.

Also...buy a "fail-safe" type of thermostat. They're designed to go bad in the open position rather than closed to forestall overheating and resultant damage.

oldalaskaman

with the engine running remove the radiator cap, if the radiator isnt full , fill it, if its full and has bubbles in the water, plan on doing some work . its a possible head gasket....or worse. after you fill it , shut the engine off with the cap still off

john 72-04

Start with something really easy. Take the thermostat out and throw it away. Bolt the housing back down without putting a new thermostat in. Now see how the temperature acts. If it runs cool now go get a thermostat and put one in. If it acts the same exact way further diagnostics needed.

GDaina

could be your fan...defective, not kicking in...

talley1968

Check to make sure the fan is operating correctly. Back in the 1970s, the fan on my '68 failed. I replaced it with a flex-fan (no clutch) and removed the AIR. Never had a problem since then.

thetasig28

Thanks for all the advise. I should have originally mentioned that the engine is new, hoses, thermostadt, etc...there is no fan clutch (runs continuously). only loses fluid when i shut the car off, seems to be running back out of the water pump into the overflow tank, then onto the ground. gonna check with a temp gun first, see if my guage is actually working correctly. Then on to the thermostadt...then??

Mike Ward

1) make sure that you're not overfilling the system. There's a 'cold' marking on the side of the expansion tank. Filling it to the top will guarantee that it will puke after shutdown

2) make sure the rad cap is the correct 15lb. rating and is in good condition.

3) don't shut it down with the cap off. The residual engine heat will cause the coolant to expand, boil and puke.

TWINRAY

I have that motor in my '67. When I ran the car as a daily driver in the 70's, I remember it didn't like hot days. Compression ratio is 11-1 which doesn't help and with carbon buildup, it'll be even higher. Make sure your timing is on the button and not overly advanced.

larrywalk

The vacuum source to the distributor makes a difference too! With "ported" vacuum, there will be little to no vacuum to the dist and the engine will run hotter. With full manifold vacuum, the dist will provide more timing (earlier spark) and the engine will run cooler after the curb idle screw is backed off to return to normal idle rpm.