2011 s4 no more heat

[Petatew]

HI i will try to explain my problem the best way I can in english.


edit 04-24-2016


( I still don't have any heat except when I drive over 70 mph )
Yesterday , while I was driving to my friend's house (+/- 60 mph ) i had the coolant/shut off engine imediately red light in my dash I saw the temperature half way between the normal and the red zone just release the gaz pedal and instantly drop to the normal zone and was able to drove to the destination safe . I immediately think the thermostat. I'm right ?? already change water pump 2 month ago








So my problem I don't have any heat in my car except my I put load on it like on a 30-70 acceleration.
the car reach the 90degree mark normaly never over heat.

First thing i've checked was the coolant, it was a low i add maybe 1/2 liter twice in 1 month.
Then I tought the problem was the water pump ( commun problem on the vw mk4 impaller strip on the shaft).
I order a WP and when I remove the old one it was ok but i still install the new one, fill the coolant let the car heat and still no heat in car except on load.
Then we checked the coolant hose that go in the heater core both were cold we tought the heater core was block so we changed it ... still no heat except on load.
The bg hose that go in the rad in the top is always cold too.
I don't realy know what to do now I tought about the thermostat but in my head if its don't work the wokd will over heat correct me if i'm wrong and i would never have heat but i still have it on load.

One of my friend said its maybe a head gasket but the cover never heat and the spark plugs are at normal ( not the usualy dry/white plug when it burned coolant.

Any one have a idea... its quite cold when its minus-40 outside ...

[Lockon_B7]

If your thermostat is stuck open it could definitely cause an issue at those temperatures. Also, are you bleeding the coolant system after each repair?

[Petatew]

Yes after each repair the only think that i can't believe with the stuck open thermostat is why the car reach is temperature normaly and keep it?

[DGVR6]

Wow -40.. That'll give any car some trouble getting up to temp.

If it takes load to start pushing coolant through the core than its either a pump problem ( you eliminated that ) or air in the system.
the core could be blocked also.

Edit: you changed the core also

Question, how did you bleed the system?

[chaos2984]

Air in the system. Ive heard this a lot on here. Does it sound like water gurgling or like a waterfall in the dash when you accelerate from a stop. If so you have air in your heater core.

[Petatew]

I don't really know how to explain it in english but i use the same way as i use to do at the dealer

[DGVR6]

Try to pressurize the system again holding it steady at 2k with the heat on full, and slide the heater core hose until the hole shows. Wait until it's a steady stream while your friend is revving to to about 1.5k. Once at idle it should be a steady stream like a water gun. Make sure you cover it with a rag so it won't spray everywhere.

If you added 1/2 twice in one month, it was burping or you have a leak somewhere.

[S4'ed]

Buy a vacuum coolant refill tool ($60 on ebay), a foolproof way to refill the system without any air pockets.

[dizzlesizzle]

Had the almost the same issue with my car...cool air plowing on idle and once moving the heat is fine. I have a thread here about it: http://www.audizine.com/forum/showth...87-Heat-Issues

They said the problem was due to the thermostat not opening and closing correctly...not 100% sure on this, could have been, but i already had the tstat replaced for the TSB a few years back. I think the cause was improper bleeding of the system or filling the system without using the vacuum refill tool. I would buy the vacuum refill tool and properly bleed the system, there is a few places that the systems needs to be bled in order to get all if any the air out. The refill. If this fails and u still get no heat or cool air at idle replace the tstat. Feel the heater core pipes too and see if one is cool.

[o1turbo30v]

+2 for bad thermostat, very common on these cars.

[Dr GP]

I would also be suspicious of the T stat. One of the most common issues with these cars

[sangaroo]

1+ for air bubble.

[Petatew]

i'm going to go to the dealer to use the vacuum machine to do a flush and fill

[theswoleguy]

same issue here from a front end collision, heard the noise and it def is air in the system if it comes back when you start driving. least that is my experience.

Get the car to temp, bleed the supercharger via the screws then bleed the heater core hose (the one on the passenger side) while having a friend rev teh car.

[Petatew]

I schedule a appointment at the dealer on Friday for a real vacuum flush n fill will see the result... only cost me a 24 ....HAHA

[S4'ed]

If the engine operating temperature is at the normal center mark of the gauge, and you lose heat only when the engine is idling a while, then the thermostat is OK. It is an air pocket that collects at the highest point (at the heater hoses in the cowl) that block sufficient coolant flow thru the heater-core when the water pump is at low RPMs. You will hear the gurgling water sound behind the dash when you raise the engine RPMs after some low RPM operation.

The usual thermostat failure mode is stuck closed....the engine will then overheat. If the thermostat is stuck open, then the engine never reaches the normal operating temperature as shown by the temp gauge (and you will have less heater output too).

The early B8 S4 plastic-body water pump failures were that the plastic housing would crack, or the bearing/seal failed, and coolant would stream out. These pumps did not have issues with the impeller coming loose on the shaft, or disintegrating.

Air can get into the cooling system 3 ways :
1) The system was not properly bleed when it was refilled.
2) A head gasket failure which can allow combustion chamber compression air, or exhaust gas being forced into the coolant passages.
3) Air gets sucked in, at some gasket or coolant pipe joint, when the system cools-off, as this causes a slight vacuum in the closed system.

[Petatew]

I didn't believe in the head gasket because I check my spark plug and they were all ok not the typical dry/white spark plug from a blowed head gasket

and i check everyway possible of the engine and to leak at all

[Petatew]

edit!!!!!!!!!!!!!!!!