Obop

Just wanted to share my 330 overhating issue with the board. See if anyone has any ideas. pretty sure I will be pulling the engine out and taking it apart anyway. I tried to do a 900 mile roadtrip and made it a little over halfway before it started surging and losing power, then the temp light came on.

I pulled over and let it cool down a good while. Made it another 70 miles before the temp light came on again. Poured water on the intake and the the middle ports were boiling the water they were so hot.

-At this point I pulled the thermostat out. I replaced it right before the trip and thought it could be faulty. Did not have access to boiling water to test it.

-Once the thermostat was out, I was able to drive the car 200 miles before it began overheating again. Went through the same process of cooling the car down, and I replaced the thermostat. Car went 5 miles before overheating again.

-Pulled the thermostat out again and the car went another 100 miles before overheating.

-Tried cooling it down several more times and it would last 10-15 miles before temp light again.

-Gave up and had it towed home with my AAA premium membership

-Water pump is working as I see water sloshing around in the radiator.

-The car was puking out a bit of coolant at every long stop until shortly after the overheating issue. Even though it was full, it would not puke out coolant from the overflow anymore. I found this strange.

-Paint is discolored on the engine at this point. Oil light came on at some point and looked like it lost its viscosity

-Got it home, changed the oil. Starts right up with no weird sounds or noises. No smoke. Does seem to get warm fast.

Any thoughts on what it could be?

edzolz

Is it running like a stream from one side to the other or bubbly like it is boiling? Possibly a blown head gasket or cracked head.

Fun71

That was the exhaust crossover causing the water to boil. It's normal for that area to be extremely hot.

Sounds similar to my 70 Supreme back in high school. After the rebuild, I did not torque the head bolts with the stud top portion as I didn't have a deep enough socket. Discovered that the engine would overheat after driving for a while due to the head gasket leaking slightly.

FStanley

read this..


https://classicoldsmobile.com/forums...take-heat.html

olds 307 and 403

Does it have the original head gaskets? If was used for coolant, they may be corroded and leaking, I have seen it before, a pressure test should be done. I have seen bad new thermostats before but removing it then replacing it should eliminate it. Make sure all the factory air dams are in place. Get a new rad cap and maybe get the rad cleaned or replaced.

4SPEED67

do you have a clutch fan? If so that could be bad. also have your radiator boiled out and cleaned. I had the same problem and those 2 items fixed my problem.

Obop

Wanted to update this thread. I had the radiator boiled out and pressure tested last month. Also replaced all hoses and flushed the cooling system along with several other maintenance items. I have noticed the exhaust ports on the intake get too hot to touch within 30 seconds from a cold start. Is it possible the heat diverter ont he exhaust manifold is stuck?

oldcutlass

You can check the heat riser by moving the swing counterweight by hand to see if it moves and snaps back into position.