Coolant Issue

A6 All/ S6 All
#1

Here in Texas right now we’re dealing with very cold temperatures of around the 20s, and so everything is being affected. Seeing as my car sits outside, it’s frozen to a decent degree and after finally thawing open my driver’s door decided to turn the car on. After turning it on, the check coolant message appeared prompting me to open the hood and check the coolant levels.

It looked significantly lower than the minimum. Is this typical for the coolant to contract that much to where it would trigger the check coolant levels? There’s no sign of a leak, but I’m just curious and somewhat concerned.

How easy is a DIY coolant change? Is it safe to simply add more coolant mix in?

#2

Yes you can just top off your coolant without issue.

My car seems to go through coolant at a fairly consistent rate, I usually get a “low coolant” light about every 5k miles. In my case, whatever causes the coolant to slowly disappear doesn’t seem to be causing any other issues, so I just top it off and continue about my business. Since I have to add a quart or 2 of oil every couple months anyways, I just make a point of checking the coolant at the same time.

In my opinion, it’s not really a problem unless you’re actually seeing coolant leaks somewhere, or needing to add coolant more than onnce every 5k miles or so.

That said, coolant leaks are not rare in these cars, so it’s worth looking into. Fill it back up, and keep an eye on it to make sure you aren’t leaking coolant onto the ground. In the last couple years I’ve had to replace a lot of different hoses, and my radiator, and my expansion tank, all because of coolant leaks, and I STILL have a little bit of coolant going somewhere. The coolant system runs very high pressure, and the engine bay runs very hot, so the combination of the two causes coolant parts to fail faster than in most cars, I think.

#3

My coolant was slowing weeping out the backside of the water pump. Could see coolant crystals at the bottom. Check there?

#4

I was actually just about to make a thread about this.
My S8 also goes through coolant at a high rate. ANY coolant dissapearing is not right, for ANY vehicle.
It is either an internal or external leak.
Im going to pick up a block tester to see if there are any combustion gases entering the system.
Even my wife notices, fully warmed up, sitting at traffic lights, our s8 is smoking white out the back while no other vehicles are.
I know blown head gaskets, produce thick lingering white smoke,
this just looks like normal water vapor…but why only the s8 and not the other 10 cars?

Im fairly convinced I dont have a coolant leak, but I need to put some dye in it, run it, then check again. May be hard to see some times. I dont have a lower engine cover either, and am not seeing and coolant on the ground…

Where else can coolant enter? both throttle bodies are heated by it, the head gaskets…and thats it i think? Oil is good and has no contamination. and car does not over heat…

#5

Yeah, mine had quite a bit of “normal” smoke when the weather dropped to around 30-35 degrees. I figured it was simply because the weather was cold and our engines run very hot, but if there’s no evident leak (like in my case as well) then it has to be a cylinder head gasket. Which how much does that run you or is it a simple DIY?

#6

Ohhh wait, okay. I’m SUCH A NOOB. Cylinder head gaskets are between the cylinder head and manifold… ha. Interesting.

#7

no cylinder head gaskets are between head and block.
a block tester with fluid is like 25-50$ on amazon or can rent one too

#8

Maybe the wrong terminology, but that’s a place that’s reached by removing the intake manifold yeah? As in it can be located by simply following the carbon clean DIY guide and it’s the step right before actually cleaning the valves?

#9

Those are intake manifold gaskets

#10

Ah ok, so this yeah? I thought this was only for potential oil leaks? Coolant has a play in that as well?

[img]https://www.audiworld.com/forums/attachments/a6-s6-c6-platform-discussion-58/53429d1454956844-valve-cylinder-head-cover-gasket-valve-open.jpg[/0img]

#11

lets back up.
I am saying, the only places an internal (ie entering combustion chamber) coolant leak may occur, as far as i know, is the two throttle bodies, and the cylinder head gasket.
Unless the head has a crack allowing coolant to enter, however this is not normally a thing on these engines, and would usually cause other overheating or over pressurization of the cooling system as well

#12

Alright, that would make sense. Definitely something to consider and I appreciate clarification.

#13

Have you pulled the undertray and checked the w/p?

#14

I’ve been thinking about checking out these strips:

http://www.acustrip.com/products.html

Was watching a youtube channel and the guy was using it on his car to determine if there was coolant in the transmission fluid because of the transmission cooler being intergrated in the radiator. Pretty slick stuff.

#15

you can always top off the coolant at any time. Just don’t do it within 45 min of driving the car unless you want to get blasted with coolant from the pressureized system.

To check for leaks pull the under pan and see if there is any standing fluid. Changes are there won’t be. The next thing to look for is to get a flash light and start looking around the back of the cylinder heads and the back of the motor for white to pink crusty powder. The OEM coolant can weep out and when it does you get a white residue.

What is common is that under driving pressure the coolant system if there is even a small leak will bleed off coolant. When you come to a stop the coolant system pressure is reduced and its normal for a small pin hole to quickly reduce leakage. What can further be frustrating is that when you turn off the car and the system looses all the pressure there will be no leak.

So you can only see or find the leaks under drive system pressure. Coolant in the oil would be obvious and easy to spot.

Usually those are the two quick things to look for.