heat issue, help please

[f4m0u5]

Cars been fine heating up for me while siting at idle for the past few months (start car for 10 mins then get into a warm car with the gauge reading 1/4 of the way up). Untill today started my car for 10 mins and then sat inside car for 15 more minutes on break to realize the car never started blowing hot air.


Check my gauge and it looks like the coolant was up to normal temp but no heat.

Started the car again for 10 minuteds 2 hrs later and got in the car and realized the gauge says its already fully warm again and sgill no heat from the heating system. (I swear even after 15 mins of idleing my car never reached operating tempature so idk why the coolant would heat up faster on a day its only 10 degrees outside)

As soon as i started driving to go to the store the car started blowing hot air



Could this mean theres shit in my heater core and i gotta flush it out?

Car had full service done 10k and 8 months ago. Including waterpump (metal impellar) new metal thermostat housing and thermostat. And new ect sensors. Alway use g12/g13 and my coolant isnt dark it looks bright pink.

[B501S4]

Could probably use a flush if it has never had one. I used this as a guide when I did mine (A4 but still works for our application) http://www.audiworld.com/forums/a4-b...w-pics-349252/ May also need to bleed if any air is trapped but seeing as this just started to occur and you had a service not too long ago that probably is not your issue. Worst case it is going to be the heater core on its way out. Would suggest OE if you have to go that route because it is a pain to get to and better not to cheap out on an aftermarket replacement.

[f4m0u5]

Thanks alot! How many hours labr are we talking for replacing heater core worse case?

[B501S4]

Not really for the feint of heart. Here is a link for a time lapse by one of the members here. There is a lot that goes into it so I would suggest starting with a flush or two, seeing if you can remove any of the debris (if any) and then go from there. https://www.youtube.com/watch?v=dRwDpXXxCLU

[f4m0u5]

Ya that would take over my stage 3 build lmao. Hopefuly it just.needs a flush. The car had heat on way home so it was prob something stuck that didnt move with the lower coolant pressure at idle.

[f4m0u5]

Flushed the heater core yesterday, it didnt need much pressure at all and came out pink looking like it goes in.i could also freely breath through it. So that isnt clogged and probably wasnt the culprit knowing thos morning it did yhe same thing, cars coolant temp went up like normal but no heat at idle.


I then tried to bleed the system at the hose to heater core and i cpuldnt get air or coolant out of the hole at idle.

As soon as i reved the car a tiny bit it started spraying coolant out of the hole.

It seems as if i have low coolant pressure at idle. What could cause this? Is there a valve stoping fflow to heater core that could be freezong up or something? My waterpump was just 8 months ago

[Zba]

First of all; it's a 99.99999999% chance need a heater core. Read the archives.

If you don't have coolant coming out of the bleeder hole re-bleed.

With the car off, open the bleeder to the right of the power steering pump. Raise the coolant bottle (although probably not necessary at this bleeder) and remove coolant res cap.

Once you get coolant and no air bubbles out of that bleeder move to the heater core hose (return, right side of vehicle). For this one it may be beneficial to raise the reservoir and get it higher than that bleeder hose. Now go get some coffee since this may take a while.

Once coolant comes out of this hole in a steady stream push the hose back on, top off coolant and get up to operating temp holding rpms at 2500-3000 rpm. I like to blip the throttle once in a while. If there is still no heat pull the heater hose back and see if you have flow. If there is no flow you still have air somewhere or have a plugged heater core.

Like I and others have said before; you need a heater core.

[Nizmo]

-Check Coolant Level
-Fill to proper level (start vehicle, get operating temp, open bleeder and let out air, close bleeder, refill coolant level)
-Check Thermostat Operation (Bring car to operating temp. Feel lower and upper radiator hoses, should BE HOT)
-Possible in cold temps, for water to freeze with incorrect coolant ratio, if heat when REVVING past 4K RPM (its your PUMP)

Thermostat is very common failure, but will also create excess pressure and possible overheat if stuck closed.

[Protection]

-Check Coolant Level
-Fill to proper level (start vehicle, get operating temp, open bleeder and let out air, close bleeder, refill coolant level)
-Check Thermostat Operation (Bring car to operating temp. Feel lower and upper radiator hoses, should BE HOT)
-Possible in cold temps, for water to freeze with incorrect coolant ratio, if heat when REVVING past 4K RPM (its your PUMP)

Thermostat is very common failure, but will also create excess pressure and possible overheat if stuck closed.

Air in the heater core will also result in no heat at idle, and heat above 3k RPMs


Sent from my iPhone using Tapatalk

[getslideways]

/\ just about to post the same thing.

[Nizmo]

/\ just about to post the same thing.

Agreed, but how did the air get there?

Would seem pretty simple diag for a heater core... Seems and my experience telling me its something else :/

*Edit- noticed he did do a t-stat and pump. I've had issues with t-stats 9/10 times, only had a blocked heater core 1 time.

( Heater Core replacements are a true PITA)

[Zba]

You guys are nuts. Every singe S4 I and my friends have owned has needed a heater core.

We were replacing heater cores under warranty back in the for crying out loud.

Could be air, most likely blockage. Both will exhibit no heat at idle and heat when it's revved up.

[f4m0u5]

I dpnt get why it would flow water no problem and air when i blew through it. I think there was air in the system the second time because i did not get a chance to bleed the car last night as i said above. So could have been air in the system at the heater core for sure. And i did bleed it at idle through the heatercore hose . Will report back if it hapoens again without finding air in the system

My mixture is at 60 40 coolant to water, shouldnt be that. Ut has been extra cold out here tho. 10 ° f without wind chill factord in

[Zba]

Because it doesn't plug up to the point of zero flow. There are multiple paths for coolant to flow inside the heater core. When some of these partially plug up you have weak heat, especially at idle. Once the revs shoot up, the velocity of the water can overcome some of the blockages.

Always use distilled water and OE coolant. Doing this should minimize this from happening.

Not my pic btw but the cores I've done have sediment in the bottom of the core and this shit in the tubes.