D Spin

Hi all, has anyone done a complete coolant drain, flush and refill on their 3.0T?

Doing a bunch of service including PCV, Tstat, and new coolant pipes. The water pump was replaced about 6 months ago, I was in a bind and had to go to a random shop for the work. The shop that did it used 'universal' pink/violet coolant that claimed to be safe for all German vehicles. The shop refused to drain the coolant and use proper Audi spec coolant when I asked them what they had used. I contacted Audi and they said that generic coolant would be fine for a few months but that it should be completely flushed and replaced with proper coolant.

I drained the coolant from the oil cooler lines as well as from the passenger side line that runs to the coolant cross over pipe.

Based on the amount of coolant that has come out, it still seems that there is a lot of coolant in the system. Should I keep removing coolant lines to drain them? Is there a coolant drain plug on the block somewhere that I'm missing? Guessing the heater core is holding a lot of coolant but can't see anywhere to drain the core.

May need to just fill with water a few times and keep draining to flush all the old coolant out but wanted to see if anyone else has any tips or tricks?

bg_2007Q7

YouTube is your friend, my friend. Can't tell you how much money it has saved me, since I bought my Q7...

D Spin

YouTube is an excellent resource however this video is also a very good example of how YouTube contains a lot of poor information.

First of all the cooling system holds 15L of coolant. He maybe replaced 8L at best. This is not a flush, nor is it even a good method to replace old coolant.

Secondly, the 3.0t is notoriously difficult to bleed all of the air out of the cooling system. The method demonstrated would not come close to purging all of the air. At a minimum air MUST be bled out of the supercharger using the two bleed crews on top of the supercharger. There are also a number of other bleed screws in the cooling system that should be used to purge air. Air stuck in the supercharger can cause serious damage.

Youtube is great but there is a lot of poor info to watch out for.

'10Q7TDI_Prestige'

You are correct regards to missing info and folks often doing things 'on the sketch' when making car care/repair videos. Best practice is to locate a number of threads and videos via internet search and do the legwork to accumulate a depth of knowledge on a specific repair/service topic.

As to the coolant's color, Audi dealers source theirs from a specific Euro supplier and so it's one color if you buy it from them (Pentosin is the OE mfg., BTW), but here's the actual history/color breakdown:

VW BASF Colour Description
G11 G48 green/ blue- green Standard for coolant with inorganic acids.

G12 red/pink Volkswagens first coolant with OAT formula and free of silicate. Do not mix it with G11 coolants! Aggressive chemical reactions attack the cooling system and the lubricant would clump together.

G12+ G30 red/violet As reaction of the mixture problems between G11 and G12, the G12+ was designed. It can be mixed with G11 and G11 coolants. It is free of silicate.

G12++ G40 red/violet The successor of the G12+ coolant was used in every VW and Audi car. It shows an improved corrosion protection, higher boiling point (135 degrees) and better heat dissipation.

G13 purple
The glycol based G12++ was replaced by the glycerol based G13 coolant. The advantage of the G13 lays in a better economic safety and lower production costs.

Of course, Audi dealers want to sell you exactly what they stock = VW/Audi branded fluids & parts = more profit for them.

When I've needed to top up in the past due to unknown coolant leaks, I researched this and found the aftermarket, Euro car, long-life, violet coolant specified for this type engine (OAT type coolant) is fine, and I keep some on hand now.

FWIW, I search out the OE/OEM supplier parts/fluids to pay less than Audi/VW prices for same product, and on something as ubiquitous as coolant, motor oil, gear oil, ATF, DEF, Filters, etc., well I get the VW spec required and go to the internet to see what matches the exact specification required, and verify the products I buy have the correct specification; I read the labels front & back and review certifications on fluids.

Hopefully this coolant chart showing what colors match to what grade/rating of coolant will help some folks, but the internet is truly your friend...the Audi dealer, not so much.

bg_2007Q7

Apologies, didn't watch the video. Just looked at the transcript, which said it was for a 3.0T.

But yeah, I've gotten some pretty crummy info from YT. In most cases, however, it is a useful tool.

D Spin

All good, it's a good example of what NOT to do, haha. Also realized he used a specific gravity tester for the coolant, doesn't work for G12/G13 Coolant.

Out of curiosity I used this technique to drain coolant, I got 6L to drain this way which seems like a lot but given that the system holds 15L it's barely a third of the total coolant, hardly a 'coolant replacement'

Being as there seems to be little info out there specific to the Q7 I'll try to put together a DIY for a complete coolant flush/drain and proper refill. I found four points to drain coolant from that netted me approximately 12L of coolant so not bad, the rest is in the block and heater core. Pulled vacuum on the system and was able to coax another liter or so out but seems impossible to get it all to drain by gravity. I have since refilled the system twice with water and it's still coming out red when drained. From what I have read online and a reference in the Elsawin, a true flush means filling with water until it drains completely clear. For the 3,0t this is about four complete fills and drains. Planning to do two more flushes over the weekend and hope that gets all the junk coolant out and ready for a proper refill.

Will try to type up a DIY with some pics and post up the link here when I'm done.

pharte

D-Spin: Did you ever figure out how to drain all coolant. I am having the same trouble and getting conflicting information from the dealership.

kelisko

Not the same car and not the exact same engine (mine is the next generation 3.0T Supercharged CREC engine, same engine in the Q7 MKII 4M) but I believe my detailed tutorials below can help.

DRAINING



FILLING


BLEEDING ENTIRE SYSTEM


BLEEDING INTERCOOLERS