Mechanics

OLDSMOBILE CUTLASS RADIATOR PROBLEM

1972 Oldsmobile Cutlass • 226,000 miles

Car is overheating (hot light comes on) after only 5 mile round trip, though return is all uphill - altitude gain about 500 feet.
In 30 years I have had car, it has no overheating history.
Car has original engine.
Radiator was replaced about 3 years ago with an aluminum core, plastic tank one.
Replaced heater core about a year ago.
Water pump about 4 years old.
Car is driven about 4 - 5,000 per year.
Coolant has been emptied and replaced several times, so it is clean and green.
Hot light came on a couple of days ago after freeway ride of about 8 miles for first time.
I put heater on and it went off after about a minute, but then flickered back on.
When I got home, about 5 miles after it came on, coolant came out of radiator through overflow hose.
Next morning, I checked for leaks. There were none.
Put in about a gallon and a half of coolant and water.
Did test ride today (outside temp 70º) and it overheated (hot light on), though no boiling over, after only 5 miles.
I opened hood to check.
Hose from thermostat to radiator was firm and hot.
Radiator was warm on the upper part of the core, cooler as it went down, and cool at the bottom.
Return hose to water pump was warm at best.

Using a laser thermometer, the temperature sender was 232º.
The upper radiator hose at the radiator was 220º.
The upper part of the radiator was 160º.
The lower part of radiator was about 80º.

With radiator cap off, it does look like there is circulation, and as it warms up, the coolant level rises and a bit comes out of the radiator cap opening (about a cup of coolant)

I took off upper hose at radiator.
No sign of blockage.

What do you think is wrong?
What should I check?
Thanks

Avatar
Guest
November 22, 2012.




MAYBE SQISHY RADIATOR HOSES S. UCKING FLAT?

DOES IT HAVE A FAN CLUTCH. COULD IT BE DEFECTIVE?

THE MEDIC

Tiny
CJ MEDEVAC
Nov 22, 2012.
Remove the radiator cap and put a running water hose in the filler neck of the radiator. Take the top hose off on the radiator. Start the car up it will run until the thermostat opens. Then you'll see water flowing out of the upper hose. The hose will fill the radiator back up. Let it cycle like this three times. If this looks good then you have to do a carbon test on your cooling system for a blown head gasket. They sell them at all the parts stores.

Cadieman
Nov 23, 2012.
Thanks

I considered it might be an exhaust leak from head gasket, but then wouldn't the radiator also be hot?

Also, I didn't see a lot of bubbling in the coolant in the radiator or any white exhaust smoke.

The upper radiator hose is very hot, but the radiator gets cooler as you go down, and the lower hose is barely warm.

If it was the head gasket, I thought the whole system would be hot?

I will check as you suggested, but just trying to understand how head gasket leak would still leave cool radiator.

Thanks

Tiny
Srbz
Nov 23, 2012.
MAYBE YOU JUST NEED AN EXHAUST MANIFOLD GASKET

THE OVERHEAT IS UNRELATED

DID YOU EXPLORE MY ANSWER AT THE TOP--BELOW YOUR QUESTION?

REVVING THE ENGINE AND HOLDING IT AT AT A HIGHER RPM (LIKE 1500-2000 RPM) WHILE YOU PAL LOOKS FOR A HOSE S. UCKING FLAT (UPPER OR LOWER RADIATOR HOSE) MIGHT SORTA BE A TEST

THERE ARE OTHER POSSIBILITIES FOR AN OVERHEAT

THE MEDIC

Tiny
CJ MEDEVAC
Nov 23, 2012.
The radiator cap is only rated at like 22 pounds psi. When the compression leaks into the coolant system it raises the pressure over the 22 pounds and that's why it overflows into the coolant hose. First things are the parts store pickup that kit that checks for hydrocarbons in the coolant. Then you'll have your answer.

Cadieman
Nov 23, 2012.
The hoses do not suck flat.

I went to auto parts store to get the CO test kit, but it will take a few days to get.

In the mean time, they suggested I try to pressure test the cooling system to see if there were any system or head gasket leaks, and had a kit to loan.

I pumped the cooling system up to 17 psi.
I let it sit for 20 minutes and it dropped maybe 1/4 psi.

Will let you know what happens with CO test in a few days when I get it.

Thanks

Tiny
Srbz
Nov 26, 2012.
I got the Lisle test kit, set it up, and put in the blue fluid.

I took off radiator cap, let the engine warm up.

Up put tester in, used my vacuum pump to draw radiator air into test fluid.

The instructions said let it bubble for 2 minutes.
I did it for 10.

The fluid remained blue.

I left the tester in after I shut off the engine so residual gases could bubble up, and the fluid remained blue.

Any ideas of what to check?

Thank you

Tiny
Srbz
Dec 2, 2012.
What color would it be if ok?

Cadieman
Dec 2, 2012.
The exhaust gas test fluid is blue to start.

If Carbon monoxide (CO) is present from a head gasket leak, the fluid turns yellow, or maybe green depending on concentration.

I got the Lisle test kit, set it up, and put in the blue fluid.

I took off radiator cap, let the engine warm up.

Up put tester in, used my vacuum pump to draw radiator air into test fluid.

The instructions said let it bubble for 2 minutes.
I did it for 10.

The fluid remained blue.

I left the tester in after I shut off the engine so residual gases could bubble up, and the fluid remained blue.

Any ideas of what to check?

Thank you

Tiny
Srbz
Dec 2, 2012.
I think the problem is solved.

Decided to go back to the simple stuff.

Took out thermostat and put on stove to test.

It didn't open at any temperature, but it had developed cracks all around the housing that let just a little flow through, which is probably why I saw a flow in the radiator.

Put in new T-stat, took on short test ride and it was improved - no overheating.

Also, infrared temp test of temp sender area was 180º instead of 220.
The radiator was pretty much uniformly hot, instead of hot at top and cool at bottom as it was previously.

Will see what happens on longer rides.

Thanks for ideas.
AD

Tiny
Srbz
Dec 2, 2012.

AD