ltooz_a6_a8_q7

Can you show the picture of the part please?

Thanks,

Louis

parkrog

[QUOTE=ltooz_a6_a8_q7;24559189]Can you show the picture of the part please?

Thanks,

Louis[/QUOTE

I replaced the entire valve assembly. See previous photo. R&R less than a hour. You helped me in past so anything you need! I can send more photos if you like. Just take off 2- 10MM nuts on front bracket and disconnect 2 rubber supports on rear bracket. (don't do 2 nuts on rear bracket.)
6 hose clamps, 3 electric plugs and its out! Easy to bleed air out with 2 bleed valves on main lines, 1 1/2 turns open them up.My Heater is working perfectly. Check operation----If water is flowing properly you can put your hand on the valve and feel if its right. The little hoses go to heater core (four hoses)you can feel the heat. Bottom two are heat to core's and top 2 are return water. Top and bottom hoses should feel close to same temperature.
If heater is on high,(both sides,) you can feel pulse as solenoids open and close. They do this constantly.Good luck.

ltooz_a6_a8_q7

Not cheap part I'm sure.

Thanks for the pics,

Louis

MP4.2+6.0

Good work. I had mine out recently to fix a pinched o ring I had mis seated when I checked it internally during my coolant change and general check. I can confirm the W12 looks just like the one in the pics.

Also notice the thing that protrudes on one side that looks kind of like a small motor housing--the portion with the green and silver label. AFAIK, that is the booster/auxiliary water pump that assists with circulation to the heater when water pump flow is low. It is powered by the third wiring connection that is down low in the front relative to the two solenoid connectors that are higher up and next to each other. In turn I believe that pump is different than an after run pump, which at least on the W12 is distinct and down under the motor and above the subframe (as in, impossible to reach w/out raising motor some). Anyway, if that auxiliary pump that is integrated into this valve block fails, it would also affect heater function at low RPMs/loads.

awdinut

[QUOTE=parkrog;24559477]
I checked my pump today, I dont think I could feel any pulsing...how frequently do the solenoids cycle, and when you put a hand on the vertical metal casings are the pulses unmistakably noticeable ?

My lower hoses were too hot to touch for longer than 5 sec, but the upper hoses were not uncomfortable to hold onto for as long as I wanted.

So, does it sound like I have a bad solenoids ?

parkrog

[QUOTE=awdinut;24560050]You feel one open and then close maybe every 3 seconds.then second solenoid does same thing.
In VagCom you can manually turn on and off each solenoid to check. You can also take off solenoid cover (4 philip head screws) and see it open and close.
I brought used one for $150

awdinut

[QUOTE=parkrog;24560334]
Today I took one of the solenoid covers off and observed that the shiny silver colored disc...the end of the rod that is supposed to move I am assuming...did NOT move. So, that would seem to confirm the cause of my lack of heat and sometime in the months before it gets cold again here in KC, I'll buy a used unit and do the R&R and have real heat once again.

Thanks to all who opined on the many posts to this thread and helped solve for me (and for a number of us I hope) the mystery of the climate control system malfunction!

alh3010

Update on my heater problem bit the bullet and put it into Audi Stirling,
After 3 days of checking they found some problem with motor for heater flap.
this unfortunately means that the dash has to come out to get to it. Not cheap either costing 958 pounds although I also got an MP3 player coded for it at same time. I hope this will be the solution, ILL UPDATE AS SOON AS I HEAR FROM AUDI.

S4-2-RS4

I know this post is ild but here it goes. Any help on a diy on how to flush the heater cores? Where to start. I am not that familiar with the a8. So any specifics would be greatly appreciated

MP4.2+6.0

I haven't seen a DIY on the heater cores that I recall, but then it isn't typically an issue other than the rarely reported leaks.

If you are struggling with heat output issues, starting points are more commonly a thermostat malfunction or the heater valve assembly that controls the water flow to the cores. Search prior posts on those if heater output is the starting point issue.