Leaking water pump replaced. Now no heat and overheating?
Asked by HCS Mar 28, 2015 at 07:10 PM about the 2004 Chevrolet Express
Question type: Maintenance & Repair
My 2004 Chevy express 3500 box truck was leaking water out of what appeared to be
the water pump. I purchased a new pump and thermostat. After replacing the pump and
filling the radiator I started engine to come up to temp. Never seemed like stat opened,
water level only went down slowly. After engine temp started climbing over normal I
turned on heater and no heat at all, just cold air. With engine climbing above operating
temp I was thinking new stat is no good but with no heat I'm wondering if something
else?
5 Answers
Just by taking a wild stab at it, I would guess that you have a TON of air in the system. If there is enough air in the system, it basically becomes vapor locked, especially in the newer engines. Best way maybe to remedy this would be to take the thermostat back out, fill the block VERY slowly with antifreeze where the stat goes until its full, put the top radiator hose back on the stat housing, then fill the hose just enough that you wont spill it everywhere when hooking it bck up to the radiator, then fill the radiator VERY slowly also. That should do the trick. They also make thermostats that are guaranteed not to stick closed if your worried about that. Hope this helps
Thank you. That makes sense. I will give that a try.
What TY said is correct . I experienced same problem. I took the hoses off. Filled as much as I can slowly with coolant . Started the van. Let idle with few revs all is good
So, instead of draining and wasting all the coolant, I had an idea to take the radiator cap off and run it until all the bubbles came out. I ran it by my dad, he said I should watch it and rev it up a bit once the bubbles start coming up. It took about 20 minutes, maybe more. Until I could count to 60 seconds without seeing any bubbles. The overflow was up to full cold, so I ended up spilling some coolant over, but I didn’t have to spend another 30$ on the 50/50 Dex cool concentrate. As a matter of fact. In my opinion, this is a decent way to go, since you will inevitably get air in the system, no matter how slow you pour it. In any case, put down some cardboard , and stand there with a rag to absorb the overflow as much as you can, and use a brick or something on the gas pedal to idle up a bit.
By the way, thank you Ty, you were absolutely correct I had this problem and I had a lot of air in the system, I was in a hurry and just fluffed the coolant through a funnel in there, without even thinking about it. So glad it was a relatively painless issue. I just replaced the water pump three years ago. I don’t remember having this problem then. I probably poured it slowly last time.
