Q: 1998 GMC keeps overheating on the temperature gauge. It's full of water and has a new thermostat.

asked by on

What's causing truck to overheat

Hi and thanks for writing to YourMechanic. There are several things to look at. First off, have the coolant tested and make sure it is within spec. If coolant is not mixed at the correct ratio, it can cause the engine to overheat.

Second, being that your truck is a 1998 there is a possibility of a water jacket getting obstructed, not allowing proper coolant to flow and cool the engine.

In this case a coolant system flush can cure this problem. Check and make sure that the radiator fins are clean and clear of any debris. Not enough air flowing through the radiator fin will also cause overheating.

Finally, there could be an electrical issue. The water temperature sensor might have corrosion which acts as resistance and will read high temperature. In this case, the temperature sensor switch will need to be replaced. You will need to have the coolant temperature electronic system checked for resistance and/or any broken/bare wire. If you would like to have this taken care of, a qualified pro from YourMechanic can come to your car’s location to inspect the overheating problem and proceed with the proper repairs.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. 1998 GMC keeps overheating on the temperature gauge. It's full of water and has a new thermostat.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Open door warning on the dash

Hi there, thanks for writing in about your 2009 Ford Flex. The small door ajar switch in one of the doors is sticking and will move after it warms up. The switch should be replaced in the door it is...

Q: Q: Car overheats; coolant leak

If the engine got hot enough to cause a head gasket failure then all of these other parts must be replaced with it. I typically do a block test to verify that the head gasket is bad. If it is...

Q: Car only runs 10 minutes before overheating - 1994 Acura Vigor

A head gasket can fail in a few ways and yes one will leak oil into the cooling system. A technician can check coolant flow with a temperature gun by taking temperatures at opposite ends of the hoses and engine...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...