Ok, I searched for a similar problem to the one I'm having with my Denali with no avail. Here's what's going on: Got this vehicle recently and I know it has been sitting for a couple years without much use. I have been going through it ensuring everything works and noticed the A/C is inop(no refrigerant charge) and the temperature of the air coming out of the vents with the temp selector on the hottest setting is not even warm. So I checked the heater hoses and control valve and broke the valve when I disconnected the hoses to it to check for coolant flow. That is when I noticed that with the engine running, there is absolutely no flow of coolant on the heater hoses at all! While I had them disconnected I went ahead and flushed the core and found no restrictions, so we're good there. Installed a new heater control valve, topped the coolant off, brought engine to normal operating temp, around 200*F and still have no heat to the core. The hose coming off the intake manifold with the quick disco fitting is hot at the connection and all the way to the core but the return hose is not even warm. I know that nothing is clogged up since I triple verified that already, and all I can blame now is the water pump since the flow is non existent. Am I right with my diagnosis? I doubt there's an air pocket causing this but it's possible, and I'm not to familiar with the bleeding procedure on a Vortec, if there is one, I'd like to know how to do it if y'all don't mind to share the knowledge. Also, the PO replaced the ever-failing intake manifold gasket set before but he could not be certain if that's when the heater failed to operate correctly. Engine runs great, reaches normal operating temp like it should, top radiator hose gets plenty hot and pressurizes and the cooling fan moves a lot of hot air through the radiator core. I know one of you has been through this and knows the fix, time to share my friends, holler!
Heater problem...
- Thread starter zomeizter
- Start date
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SunlitComet
OBS Jedi-Do Good
follow both hoses from the firewall and feel them to see where the major temperature change happens. It could just be debris in the hose. If you don't go over 200 or so while running then it sounds like you pump is just fine if you are not overheating.
I did exactly that, heater hose from W/P to core is hot, the return however, is not even warm. This led me to believe the core was clogged but I hooked up a garden hose to it and the flow is perfect, no restriction. Did the same with all related hoses. Just seems like there is very little flow to the core. The engine temp is perfect, no overheating issues at all, this sure is something I've never seen in my wrenching years. Guess I'll go ahead and do the pump and see what happens, it's probably something simple and stupid but I can't find it...I did hear some sloshing/gurgling coming from the core when I was under the dash trying to identify what I believe sounds like a vacuum leak, if this is happening, that would be evidence of an air pocket right? You know of a proper bleeding procedure for the cooling system?
SunlitComet
OBS Jedi-Do Good
don't worry about the pump right now. Does the water valve happent o seprate cold hose from hot hoses by any chance. whether from the pump or core. if not take that cold hose off sometime and have a looky for cloggings. the core will blled itself out but you need to get the coolant in it moving first. As for a bleeding procedure it wil take time but the system will bleed itself out. Just need to keep an eye on the reservoir so it does not run dry as it bleeds out the air and puts coolant in it's place.
Will play with it some more today, note that control valve is new and verified fully operational. Also, when I remove any heater hoses from any connection, I see zero flow. Will report any new findings soon, thanks man...
Will agree.
But will back up. Not sure how yours is setup or my 96 (Silverado for sure) My 99 Tahoe has the heater control valve under the hood about 6" from the firewall. (96 does not have it, sure inside the cab)
Do you have heat to/through the heater control valve?
You may need to find it if not like my 99. Had to get one for that, not the best but for $12 from autozone it's not leaking. (my problem)
Water pump will not be it if it's hot to the core.
But will back up. Not sure how yours is setup or my 96 (Silverado for sure) My 99 Tahoe has the heater control valve under the hood about 6" from the firewall. (96 does not have it, sure inside the cab)
Do you have heat to/through the heater control valve?
You may need to find it if not like my 99. Had to get one for that, not the best but for $12 from autozone it's not leaking. (my problem)
Water pump will not be it if it's hot to the core.
Heat goes through valve no prob, I found an arrow cast on the valve, I suspect it indicates flow. Had no time to check it out much yesterday, will see if I can get to it today. Do any of you know what the flow direction of the coolant for the heater is? Does it flow from the intake manifold fitting to the core or from the W/P bypass to the core? Holler...
Still no heat, so I did a google search on this and found another person having the exact issue with their vortech. I got excited to see what the fix was but the thread ended back in '09 with no solution posted, bummer. Everything you can think of was tried in order to get this fixed to include W/P, heater core, all hoses and plumbing/valves, intake gasket, etc, etc. to no avail. It was also mentioned that the vehicle was taken to a pro who put 12 hrs. of labor and got nowhere and did not charge a dime for the diagnosis attempt in exchange for the customer to return with the fix info if it was ever resolved. Ok, now I'm determined to fix this!! Just what kind of gremlin would cause this? To be continued...
SunlitComet
OBS Jedi-Do Good
all water valves are under the hood. btw are the hoses on the correct valve connections?
Proper routing was verified, got some questions:
What are the chances that the PO performed a bad intake manifold gasket procedure and is causing this issue?
Can a thermostat cause this even though the engine operating temp reaches around 197*F?
What are the chances that the PO performed a bad intake manifold gasket procedure and is causing this issue?
Can a thermostat cause this even though the engine operating temp reaches around 197*F?
