Looking for some advice here. My 05 has no heat and it seems like it lost heat suddenly although I could be completely wrong about that. Just a few months ago I remember putting the sliders to cold because heat trickles out the vent, ya know? It was a warmer day...

Around the same time I did a coolant flush and found that one of the hoses to the heater core was completely filled with brown gunk. Obviously it couldnt have been fully clogged correct? The engine would overheat? Anyway I blew some compressed air into one of the hoses while putting the other hose into a jug to catch everything. Lol ended up blowing brown crap ALL over myself and my wife. The jug was a milk jug with the opening being the same diameter as the heater core hose. Hindsight always 2020, I know.

Anyway, recently needed heat only to find that it didnt work. Its a bit warm right when you turn it on but within seconds its cool air.

Started investigating and found a very small leak in the radiator that I assume has been there since before I lost heat. I believe the heat worked well with that leak.

Ive heard running liquid or rather, sloshing that goes up and down with RPM for several years in this car and always assumed its just a small amount of air in the heater core. It is much worse now. Timing correlates with the heat loss.

So my questions are,

Could a pinhole size leak in the radiator cause me to lose heat? I know it will introduce air into the system that could ultimately end up in the heater core? The leak seems to be at the very top of the rad.

Does it sound like the heater core is just full of gunk? Is there a way to clean that out?

Any easy way to replace the heater core?

Anything else I should be considering here? I just find it strange that the heat would suddenly quit working. Remember, almost warm when I first turn it on and quickly goes to blowing cool air.

As always, thanks much.

 

I had a co-worker that helped someone who clogged the heater core on a Ford car with BarsLeak years ago. He said he fixed it by disconnecting the heater core hoses and using Draino and the garden hose. Kept pushing water in until it pushed the crud out the other end. Once they got good water flow, flushed with water, re-assembled and the heater core worked. OH and that Ford had a factory design that basically planned for "what if the core is clogged" (a built in bypass).

Now your issue. If you got an air pocket into the heater core, then definitely no heat. But I am also wondering if your thermostat is working right. If it is left open, the car never gets to the correct temp since coolant is moving in a continuous loop, thus you have no heat from your HVAC. I would also consider putting a radiator pressure tester on the radiator and make sure you are holding pressure (no other leaks).

I have heard of people changing the heater core without removing the entire dash on these. I am not sure how that works out. Years ago, I removed my entire dash to get the HVAC module out to change the A/C Evap core. I also decided "to heck with it, do a heater core now". Something I never want to do again. To make maters worse, not sure when GM did this, but in 2004, the HVAC module is held together with heat stakes. You have to drill or break them, THEN source your own screws for re-assembly!! Personally, I would do everything to avoid changing the core unless you can prove there is no other answer.

 

Check the heater hose's when the system is up to temp. If one is still cooler than the other I would try back flush the heater core. Basically connect ttwo hose's to the core to avoid getting sprayed with that nasty gunk and run water through both directions. Running a cleaner like CLR in the core wouldn't hurt . Just dump a bottle in the hoses and let it sit for a while. Personally I would avoid using a high pressure blast of compressed air, with my luck I'd blow a hole in the core.

 

In my '74, I have what's called a water control valve. It's a vacuum actuated valve that controls water flow into the heater core. If your car came with one, can't hurt to check that as well.

 

Thank you guys. Ill report back after this headache concludes. For now im just driving the 5 of us around in my 300zx LOL!

 

So it seems there are no leaks and im getting better heat but I cannot get all this damn air out of the system. I dont remember having this much trouble the several other times ive done cooling stuff.

Is it possible to have the hoses on the water pump reversed? Could that make a difference??

 

I've had the dexcool sludge problem before and I never put anything other than dex in the system. Flushing it many times for fresh dexcool, I finally decided to go green, so I flushed it good with vinegar and got it all out. I've been green since 2015, that rhymes.

I've fixed my no heat bubble in the heater core problem by squeezing on the lower radiator hose with the cap off. It seems to burp it out somehow. As the coolant goes down just add more, once it finally stops going down as you're squeezing the hose, you should be good.

I liked the old school way of doing a coolant flush where we used a garden hose adapter on the heater hoses. Just remove the thermostat but reconnect the housing and all hoses and turn on the house spigot and you were completely flushed within seconds.

 

Didnt think about squeezing the bottom hose// Thank you

 

I had some heating issues on my 2005 Impala, it did not have any heat at 20 below. The garage back flushed the heater core. When they did, I wondered if they should just do a complete system flush. They said no the heater core has smaller holes that plug up easy and it would be fine. When it left the garage it was above 0, but returned to below 0 couple nights later and again no heat. Had them flush the whole system and cured the problem.

 

Don't know if this would remove air from the heater core but in the past to remove air from the cooling system I would do this. 6th gen. Monte, drive the radiator cap side, passenger wheel up onto an object to elevate that corner of the car. Then with the cap off and the car running for 20 minutes the air pockets would burp themselves out of the system as the air is forced to the high point via the circulating fluids.