Fluctuating coolant level in new 2.0L TSI engine

Hello,

"For a few days now, I've had a Polo WRC. Of course, I often take a look under the hood, even though I don't know much about the engine yet."

What I noticed, however:
When I took possession of the car, the coolant level in the plastic reservoir was at its maximum mark, as shown in the attached photo.

After one of my trips, the reading was significantly higher, even after the engine had cooled down – approximately as indicated by the dotted pink line.
I tried opening the fill cap to release any pressure, but there was no significant overpressure released (just a brief puff of air).
At first, I thought my memory might be faulty, but today, after another trip, it's back at its maximum level, just like when I received it.

Please note: I have always tested it on a flat surface: either in the dealer's showroom or in my garage.

Does anyone know an explanation for this?

Is that yours?
Congratulations!



I had a similar observation with the Škoda as well.
Erst dachte ich da geht jede Menge verloren (bei mir war es sogar unter Minimum), doch nach einmaligem Nachfüllen war es vorbei mit dem "Verlust". Ich habe es bei meinem Händler angesprochen und bei der ersten Inspektion haben die einen CO und Drucktest gemacht. ONo findings.

It is quite normal for the water level to fluctuate. It can also occasionally exceed the "max" level slightly.

Na das ist doch mal ein Auto, damit wirst du viele viele TDI ärgern können.

Regarding the topic... Is it certain that the water had approximately the same temperature?

I also have the EA113 in my Audi, and it makes a noticeable difference in performance whether it's hot or cold.

Bertil wrote:

I had a similar observation with the Skoda as well. At first, I thought a lot was being lost (in my case, it was even below the minimum), but after refilling it once, the "loss" stopped.

Hmm, in mine, it seems more like an increase followed by a loss back to the starting value.
My spontaneous explanation would be a kind of steam bubble that didn't reform after cooling down after the single trip... but can something like that even happen?

Quote:

The fact that the water level fluctuates is quite normal. It can sometimes even slightly exceed the "Max" mark.

I am also familiar with the differences between a cold and a warm engine.
But my observations were consistently made within a few days, and always with a cold engine.

Even though the car is new, has the cooling system been properly bled?
hg
Herbert.

Herbert wrote:

Even though the car is new, is the cooling system properly bled?

It's not brand new; it's a "day-first registration" with approximately 470 kilometers on the odometer.

With incomplete venting, I have only previously observed that the coolant level decreases over several trips and then remains constant. But that it increases in between would be new to me .

I wouldn't worry about it too much right now; just make sure to properly and gently break in the engine, and then give it a good run once it's broken in. (The TFSI loves high RPMs.)

If you can assume that the coolant was flowing through the pipes at a good speed, you can get an idea of whether there were any air bubbles in the system or not.

I initially thought it was simply temperature-dependent expansion, and that the block was still quite warm during one reading, while it was cold during another.

P.S.: Please, please don't subject this fantastic engine to long-life oil or extended service intervals.

Benni wrote:

So far, I thought it was simply temperature-dependent expansion, and the block was still quite warm during one reading, while at another time it was cold.

No, definitely not.
The car sat for a little over two days, and after that, the coolant level was still "too high."

Quote:

P.S.: Please, please don't subject this great engine to "longlife" oil or extended service intervals.

I certainly don't intend to.

ulf wrote:

With incomplete venting, I have only previously observed that the coolant level decreases over several trips and then remains constant. But that it increases in between would be new to me

.

I've noticed the same thing before, but I've observed it in several (new or used) vehicles already.
After a few thousand kilometers (4-5), the problem finally stopped.

I don't have an explanation for it. However, all the vehicles involved were equipped with automatic climate control.

EDIT:
Regardless, it's good that you're keeping an eye on it!

Bertil wrote:

ulf wrote: ... the coolant level decreases over several trips and then remains constant. But that it increases in between would be new to me . I've noticed the same thing before, but I've observed it in several (new or used) vehicles already. After a few thousand kilometers (4-5), the problem was finally over.

Thank you, that reassures me.

Quote:

In any case, it's good that you are keeping an eye on it!

Of course!

Perhaps another thought on that matter:

As silly as this thread might be:
http://www.motor-talk.de/forum/kuehlmittelstand-zu-niedrig-gti-p-t5027934.html

"One user there also noted fluctuating and decreasing coolant levels due to expanding hoses."

Perhaps they have become a bit more flexible recently?