Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner
1 - 12 of 12 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
Hi everybody. I just replaced the water pump on my '04 Envoy (5.3 V8) and now I can't get any heat and the temp rises up to 225 before I shut the engine off and place a fan on the engine to help cool it.

I removed and checked the thermostat which opens around 190 and is fully open by 210 or so.

The two lines that run to the heater core (just behind and to the left of the thermostat as you look from the front) are hot near the pump but not so much further back.

I filled the radiator and overflow tank with coolant/water and after I start the engine I turned the temps all the way up to 90 but it blows cool air - no heat - then when the temp rises to 225 or so, I turn it off and cool.

Is there something I missed or is there a bleed port somewhere I missed?

Any help would be appreciated!

Thanks,
Chrisbo
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #3 ·
[SOLVED] No heat after replacing water pump (overheats, too)

Thanks for replying. I'll look for the bleed port.

It appears that I was a bit premature - I guess the higher than normal temperatures did it to me. So, after letting the truck sit over night then in the morning running the engine with the radiator cap off and gunning the engine in quick bursts, the air slowly left the heater core and I was able to get cabin heat and the engine temperature came back to normal (well, actually slightly less than normal)

All is well now. Whew!
 

·
Registered
2003 chevy trailblazer_ls_ext
Joined
·
76 Posts
i had the same problem. it seems like the system needed BURBING.

i was told to squeeze the hoses several times during operation to gather pressure for the system.

it didn't work for me so i thought it could be a bad head gasket...100k mi.

i had it pressure tested and flushed for $80. it just needed burping, but I didn't do it successfully.

i didn't think about the air in the heater coil. that would make sense and i could have taken a better approach.

V8 5.3 !
 

·
Registered
2005 isuzu ascender
Joined
·
4 Posts
Reviving a old thread. I just replaced my water pump and thermostat today. I am having the same problem as described as above. I start the truck turn the heat to full blast and get cold air. The temp starts to get to the middle of the gauge I get scared and shut it down still with ice cold heat. When it starts to get to the middle temp there is a loud sqeeking sound, which I am assuming is the belt, but could this be the bearings on the new pump starting to overheat? I'm at a loss how do you bleed from this pipe at the throttle body? or should let it run with the radiator cap off? sorry so long winded one more thing why does the coolant not come out of the res. tank? If there is air in the system shouldn;t this take it out and get lower?

2005 isuzu ascender, 5.3 vortec 75k miles.
 

·
Banned
2003 gmc envoy_slt
Joined
·
7,190 Posts
The needle on the temp gauge should read right in the middle @ 210 degrees for normal operating temps.

How long ago did you replace the water pump?

It can take a few heat/cool cycles to get the air out of the system and yes, as the air is expelled, coolant should be drawn back in from the reservoir.
 

·
Registered
2002 chevy trailblazer_ls
Joined
·
236 Posts
My temp. has always read just to the left of the 210 mark. Today I got in and hears a noise coming from the engine area. I noticed the temp was right at 210 maybe just a hair to the right. I'm pretty sure my water pump is going bad. I bought another one and will change it tomorrow. I hope I don't have any problems with having to burp it.
 

·
Registered
2009 chevy
Joined
·
6,431 Posts
You definitely have air in the system.

Sometimes, parking on a hill, nose up, and letting it idle will let the air work out.

Just be careful it does not overheat.
 

·
Registered
2002 chevy trailblazer_ls
Joined
·
236 Posts
Maybe so, but I also have play in the pulley. So I won't take my chances, I'll just change it!:raspberry
 

·
Registered
2003 chevy trailblazer_ls_ext
Joined
·
76 Posts
Inquiry on Pully Change

so did the pully change help you out ?

when i am towing with AC on, my engine gets warm, so i am thinking I should change my pully too.

i've already changed my fan, tstat, belt; but that didn't fix the problem.


there is another thread where someone put in a bypass to the fan selenoid wire so they could turn it on manually. THAT is exactly what I'd like to do, but their instructions are conceptual and NOT YET STICKY.

my thinking is that id turn it on when i am going slow and the engine is warming up past 212.
 

·
Registered
2008 chevy trailblazer_ls
Joined
·
43 Posts
Going through the same problem. 5.3 envoy. No heat, replaced WP and Thermo, no heat and hitting 260 degrees and throwning 1258 code. I've put almost 200 into this and 4 hours labor and its pissing me off.

How do I burp the system to get heat? 15 below this weekend. ugh
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top