Another cooling problem - 70 SE w/383 AT

[spamtank]

Car ran great all summer, even during some of the hottest days.  Now in the fall, the days/evenings are cooler, but after a 10-30 minute drive, the radiator pressure relief cap vents and splashes about 1/4 cup of anti freeze on the ground about 5 minutes after it has been shut off.

Think I have a 185 deg t'stat.  Runs just above the lower line on the temperature gauge.

Replaced the water pump end of last year, and put a radiator shroud back on.  Belts are tight. 

Can't figure out what's changed.  I should probably check to see if any of the hoses are collapsing during operation.  But I don't think so, they are only a year or two old.

Any thoughts? 

I suppose an air pocket some where in the cooling system could expand once the engine is turned off.  it's odd that it just started recently when the weather cooled off.

[Chryco Psycho]

not air pockets but the heads could be boiling coolant after shut down so either the flow has changed or maybe just a weak rad cap

[jhaag]

I agree with chryco. change the radiator cap. If your operating temps are still good when driving then your symptom points to the cap. If your cooling system is in good shape You might even think about putting a little higher rated cap on. The higher rate cap will raise your boiling point a little more.

[spamtank]

Good thought.  I'll pick up a new cap and try that.

[DocMel]

If its a stock radiator (40 plus years old) and the above doesnt solve it, remove it and have it cleaned/recored at your local rad shop

[spamtank]

If its a stock radiator (40 plus years old) and the above doesnt solve it, remove it and have it cleaned/recored at your local rad shop

Thanks for the idea.  Radiator has been replaced, and is in pretty good shape.  But probably worth cleaning it out.

[spamtank]

So I replaced the cap, and that seems to have fixed the problem.    Should have thought about that one a while ago. 

I usually start a repair job by replacing the most expensive or hard to work on part first.   

Thanks guys! 

[dodj]

I usually start a repair job by replacing the most expensive or hard to work on part first.   

So I'm not the only one eh?