2005 Chevy Trailblazer

WOLFPACKFAN

MEMBER
2005 CHEVROLET TRAILBLAZER
6 CYL
2WD
AUTOMATIC
75,900 MILES

Can a failing waterpump cause a car to idle rough? I took my car because it was idling rough. No other problems. They told me the water pump was running hard and I should replace it soon and they could do it the next week. I drove the car home and started it the next morning. As soon as I pulled down the street the hot light flashed and the car shut off. My neighbor let it cool and put water in it so I could get it back home. When I got back home I did see a big wet spot in the driveway. When a friend looked under the hood there is some water on the side engine. He said it could be a head gasket. There is no water in the oil, but there is a smell of antifreeze when you start it.

1 Reply

MATHIASO

MECHANIC
1,209 POSTS

Hello wolfpackfan

yes, a failing water pump could cause a car to idle or run rough.

When the engine overheats, the first thing that will happen is a gasoline engine will start to detonate. The engine will ping and start to lose power under load as the combination of heat and pressure exceed the octane rating of the fuel. If the detonation problem persists, the hammer-like blows may damage the rings, pistons or rod bearings.
Overheating can also cause preignition. Hot spots develop inside the combustion chamber that become a source of ignition for the fuel. The erratic combustion can cause detonation as well as engine run-on in older vehicles with carburetors. Hot spots can also be very damaging and burn holes right through the top of pistons.
Another consequence of overheating may be a blown head gasket, in short or long term. Heat makes aluminum swell almost three times faster than cast iron. The resulting stress can distort the head and make it swell in areas that are hottest like those between exhaust valves in adjoining cylinders, and areas that have restricted coolant flow like the narrow area that separates the cylinders. The typical aluminum head swells most in the middle, which can crush the head gasket if the head gets hot enough. This will cause a loss of torque in the gasket allowing coolant and combustion leaks to occur when the head cools. A HOT warning lamp should never be ignored. Find a shop that can replace the water pump immediately.