69monzaredbigblock

Have always had problems with air in the coolant. Tried a 160 stat,180 stat and currently no stat at all. New temp sensor says 150-190 most of the time.I checked for combustion gas in the coolant with a chemical test kit and got a negative reading. Sometimes when parked it burps up a 1/4 cup or so(embarassing at cruise nights) sometimes not at all. I don't like running without a stat, I always felt that no stat setups shot the water through the radiator too fast to be cooled . I don't have coolant in the oil and don't have oil in the coolant. This engine seems to get blazing hot to the touch fast- but the temp gauge readings say otherwise.I think the previous owner had the same problem. If there is a crack somewhere where would it be? The spark plugs all look about the same (very lean due to a sick Quadrajet) and the engine runs pretty good. I suspect it has some sort of performance cam as the engine vacuum is very low,but I don't see how that would relate to expelling fluid out the overflow. Any Ideas?

Larry B.

I would check the upper radiator hose for exact routing. I must be a formed direct fit replacement and must route in front of ( not over) the alternator . If the hose has any point that is higher than the pressure cap, air will got to the highest piont which is now the hose instead of the cap. Expanding air forces water out of the radiator cap, where ever it is. Mine is on the surge tank. This is a REAL condition that you cannot ignore. Physics! Several forum members have solved this problem with a correct and correctly routed upper radiator hose.

79ls1

I would also put the t-stat back in.

Big Fish

You might have a bad cap, not allowing pressure to build up in the cooling sytem, and therefore lowering the boiling point of the coolant. I would not trust the factory temp gauge setup either, verify the reading with a thermometer.

sjr1971

Check/sand your rad cap sealing surface. Reverse the gasket on your rad cap. Make sure it has no pits. Re-install a correct thermo. I had the same problem and cured it doing the above. Car sat on stands for 12 yrs. Corrosion was a big problem.

71coupe

Occasionally this will happen with the thermostat removed with a weak or low rated pressure cap. It's not an overheating issue, but an excessive pressure issue - without the t-stat causing a restriction.
Try installing an 18 # radiator cap and see if the problem goes away.

69monzaredbigblock

The hose is routed over the alternator. I suspected this as a problem but saw a similar car with the hose routed the same way. That owner had no problems (he claimed) with pushing out fluid. The stat housing hose connection points up at some angle making the routing of the hose in front of the alternator difficult, so I will replace the housing with one that goes straight out and reroute the hose as you suggest. May as well put a stat in at the same time. I hope this cheap fix does the job.Thanks for taking the time to help.

69monzaredbigblock

I think a 160 will do the job, thanks.

69monzaredbigblock

New 16 lb cap. I will check out the gauge ,thanks.