How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Eric Your Own Question
Eric, Automotive Repair Shop Manager
Category: GM
Satisfied Customers: 32383
Experience:  20+ yrs. experience as repair shop manager and technician.
Type Your GM Question Here...
Eric is online now
A new question is answered every 9 seconds

2005 gmc envoy xl: a radiator..overheating..coolant..water pump

This answer was rated:

I have a 2005 gmc envoy xl that recently had a radiator and thermostat changed, yet it is still overheating i.e smoking, bubbling from the coolant compartment and eventually cuttiing off. Do I need to replace my fan and/or water pump or is something else the problem?

are you having to add coolant to it regularly?

when it is running hot, is the fan running?

Customer: replied 6 years ago.

Yes, the coolant evaporates quickly and I keep adding it in compartment. I do believe fan is operational.


you need to check the water pump by filling the overflow reservoir and then starting engine(when engine is cold). If water pump is working, it will suck the coolant from the overflow into the radiator within 5-10 minutes. If it doesnt, then replace water pump.

However, I suspect a possible headgasket leak(they dont always cause water in the oil or white smoke from the exhaust). To confirm, a Block test is done. you can buy one from Autozone for about $30. It is a glass tube with dyed liquid in it and a small pump handle. you attach it to the reservoir cap opening, crank engine and allow to run for 10 minutes. pump handle and observe liquid in it. If it turns bright yellow, then there are combustion gases in the coolant, which means a leaking headgasket
Customer: replied 6 years ago.

currently engine wont crank, how else can i know or check if its waterpump or head gasket leak


cant really test a water pump for proper operation if engine is not running. if you have a high pressure air hose, you can remove the spark plugs and blow air into the spark plug holes. If you hear air escaping from the intake or exhaust, then you have a headgasket leak. No other way to really test it beyond this
Customer: replied 6 years ago.
Head gasket more than likely then right. Thank you.

yes, unfortunately, it is most likely the headgasket. The one telltale sign is the coolant bubbling into the reservoir. This is normally due to the pressure difference in the engine crankcase and the cooling system which forces the coolant back into the reservoir
Eric and other GM Specialists are ready to help you