1999 Chevy Suburban Overheating

KARAVAN

MEMBER
1999 CHEVROLET SUBURBAN

Engine Cooling problem
1999 Chevy Suburban V8 Two Wheel Drive Automatic 150K miles

We noticed the water temperature was changing from 190 degrees to red line hot and then back to190-210. It varied almost constantly.

Replaced the radiator cap. It had an 18 PSI and was replaced with an 18 PSI cap with relief lever. That seemed to stop the problem but the car cooled down in the meantime.

A leak near where the AC would depense condesation water has a red tint to it and is a bit sticky.

Is this probably the water pump causing this problem?

Do you have a procedure for replacing the water pump?

Thanks,

Bill Berry

1 Reply

CARADIODOC

MECHANIC
33,871 POSTS

Hi karavan. Welcome to the forum. That red tint you mentioned indicates a leaking heater core. That could result in overheating due simply to low coolant level.

Before replacing the heater core, use a cheap digital voltmeter to measure the voltage of the coolant! Put one probe on ground and the other one in the coolant in the radiator, but don't let the probe touch the tank unless it is plastic. If you find a reading of 2 - 4 volts or more, the coolant has excessive acids in it. Acid and two different kinds of metal form a battery and cause "galvanic action", (corrosion). That acid will eat through your new heater core in a few months.

The best thing you can do is get rid of that red Dexcool (Dexmud) antifreeze. GM advertised it as "lifetime" coolant but on the reservoir you'll see it says to change it every three years. Even the Dexcool company never claimed it to be lifetime coolant. To change over to something better, ALL of the Dexcool must be flushed out of the system since it is not compatible with other brands.

Caradiodoc