chip-powell

Took the wife out for a drive yesterday. It was a short one, only about an hour or so. When we got home and I shut down the car, I noticed that the radiator overflow hose spit out about a cups worth of antifreeze onto the driveway. It was definitely from the hose and NOT the water pump. The Olds was not running hot while we were out, but she's never done this before.

Any ideas on what I should check?

oldcutlass

You probably overfilled the radiator. The level should be about an inch over the transmission cooling lines and there is a mark on the back of the radiator. The coolant needs headspace to allow for expansion when it heats up. If the level is correct, then you may have a weak radiator cap.

Fun71

Heat continues to build after the engine is shut off and the coolant flow stops - all that engine heat transfers to the coolant in the block, which can then cause some to puke out. Do you have an open system without an overflow tank? If so, make sure the coolant level in the tank is at the FULL line which is about 2 inches below the top of the tank to allow for thermal expansion.

Vintage Chief

Somewhat a classic sign of a bad/faulty radiator cap. As Kenneth noted, after car is shut down, heat continues to be absorbed into the system. With no air circulating over the radiator (as there would be while driving the vehicle) to dissipate the heat, the temperature can rise & fluid can puke from the overflow tube. It's the exact symptom I've experienced on several classic vehicles. R&R the radiator cap.

chip-powell

Thanks guys.

tnswt

Don't assume because the cap is new that it holds pressure. My experience is that a good percentage of new, out of the box caps, and those caps supposedly rebuilt by those specializing in the practice are faulty.

Procure a tester and do your own testing to pass the radiator cap. Down the road, the cap should be washed, inspected, and retested at every coolant change.

My guess if you have recently added coolant or changed your coolant that you simply overfilled and the system is purging excess coolant through the overflow tube.

Happy Motoring!

Koda

What's a good tester for cap and radiator?

70W-32

Ive had a Stant brand for about 30 yrs now. Its basic, the pump, and the cap tester adapter. Only fits radiators and caps the same size as used on our Oldsmobiles and similarly sized American cars. Ive noticed Some newer cars use a different size cap, so if you want a kit the fits everything, probably a Matco, or MAC unit. Snap-On is almost $300. The Stant is about $90

STANT KIT

Vintage Chief

Speaking of Stant. I've been very pleased with the construction & performance of a Stant radiator cap.

tnswt

I also use the Stant tester.