VW Golf R 2016 coolant system problem.

[LLV Racing]

Hello,

I have a VW Golf R from 2016 and I have some problems with the cooling system.
When the car is fully heated, the coolant level is between minimum and maximum.
Every time I stop the car, I notice that the coolant in the expansion tank rises very quickly by 3-4 centimetres above the maximum level, even above half of the tank. When the engine cools down completely, the level drops by 2-3 mm but remains well above the maximum.
After I make a trip with it and the engine reaches the optimal temperature, the liquid level is again between minimum and maximum.
I connected an OBD 11 diagnostic and the temperatures at which it works are correct. A maximum of 107 C at idle and easy driving and drops to 85 degrees when I accelerate hard.
The coolant is clean without traces of oil, as well as the oil without traces of coolant.
The climate in the car works very well, it makes hot and cold.
I changed the whole water pump assembly but nothing changed.
What do you think could be the problem?

 

[iichel]

I wouldn't worry too much, coolant levels may very well rise and drop with temperature. It sounds like you have no cooling issues and no contamination.

 

[JerseyDrew77]

Did you change out the water pump or a shop?

 

[Jachas]

Maybe valve in coolant cap is not working as it should? You can test the cap with V.A.G 1274B + adapter V.A.G 1274/9. Around 1.6-1.8Bar is needed to open the valve in coolant cap ( OEM/dealer way) In house/DIY gonna be easier to check the cap (and coolant system for leaks), unplugging small upper hose on the expansion tank (close to the coolant cap), sealing the hose (with some screw for example) and connecting compressed air with some pressure gauge to the expansion tank

 

[LLV Racing]

The water pump was changed by a VW mechanic. I changed also the coolant tank and the cap.

 

[JerseyDrew77]

The water pump was changed by a VW mechanic. I changed also the coolant tank and the cap.

Did you run the process of making sure you got out any air pockets/bubbles in your coolant lines?

 

[LLV Racing]

I think the mechanic did that.
Anyway, from what I've read, the system is self-ventilating and no specific procedure is needed.
if you have other information, please tell me.

 

[JerseyDrew77]

I think the mechanic did that.
Anyway, from what I've read, the system is self-ventilating and no specific procedure is needed.
if you have other information, please tell me.

It is self ventilating to dome degree. Wait for your car to be cold and if you unscrew the cap all the way but don't remove it, start your car up and let it idle till you see the temp is up to operating temp. That will let any tough air pockets out.

 

[LLV Racing]

I will do it. Thank you.

 

[Al_in_Philly]

When you stop the car, the coolant is no longer circulating, yet your cylinder head (the hottest part of any engine) is still carrying all of the heat from the combustion before you shut the car down. This often causes the coolant in the head to super-heat within its channels, briefly surging into the overflow tank. Frequently, one can actually hear this surging from outside of quite a few cars, if you listen for it. Many cars will run the radiator fan after the car is turned off to aid in the cooling of this especially hot coolant. As you've noticed, once everything has had time to cool off, the residual levels wind up being back to normal. Unless you start to see either the engine running hot or have a significant drop in your coolant level, I wouldn't worry about it.

 

[JerseyDrew77]

I will do it. Thank you.

So did it work for you?

 

[LLV Racing]

Unfortunately no. I went to the dealership yesterday, they vented the system and changed the coolant. It worked fine only yesterday but today when I got to work I turned off the engine and the fluid started to rise again.

 

[LLV Racing]

I made a movie in which you can see how the liquid increases when the auxiliary pump starts and decreases when it stops.

 

[Samb]

Hello, everyone.

I need advice please.

MK7 R - 55k miles

On occasions, the vehicle emits a gurgling sound after being turned off after a regular drive, as well as some other sounds, although these do not appear uncommon and are simply the result of typical electrical components/vehicle cooling down.

The extent of a journey makes no difference; it can occur on a short trip of as little as 5 miles or a long journey of 25 miles or more.

The sound is coming from the driver's side of the vehicle. I believe it is related to the coolant reservoir.

I carried out numerous checks:

There is no white or milky smoke (the vehicle has generally had major services, haldex, and DSG from Volkswagen). Another major service was carried out, as well as brake fluid replacement, on February 10th, with no issues noted. Everything is fine with the maintenance list report.

There is no white exhaust smoke unless it is cold, which is due to chemical reaction (condensation).

No loss of power. The vehicle performs as intended. There are no difficulties.

No water or strange odour (I've read online that if the coolant isn't visible, it's being burned and may have a strange odour.)

No overheating. Engine and oil temperature are always within the optimal range. There are no issues to report.

No noticeable damp spots or puddles. There are no white, dried-up water/coolant streaks.

The diagnostic scan returns no codes relevant to the problem and indicates the vehicle to be in good condition.

Coolant needs to be replenished approximately once a month. If driven in race mode, it may operate as a catalyst, necessitating topping up after three weeks roughly.

With frequent coolant top-ups. I am almost positive there is a leak, and the water pump/+ thermostat housing may need to be replaced.

Would you also agree that the car requires a water pump and thermo housing replacement as it is approaching the 60k mark? I understand that water pumps do not have set mileage limitations and can malfunction at any time.

I do not believe it is a head gasket leak for the reasons indicated above.

I've read about air locks and heater cores online. Could that be the cause? (I don't think so; my heaters heat up and blow hot air as they should. Sometimes too hot for my comfort, but then again, it's a performance car that heats up fast and emits a lot of heat).

Or is it purely because it's a performance vehicle and the coolant is running low due to utilisation? Also, I checked the coolant level and reservoir tank after about 5 minutes of shutting off the vehicle, and there is no major buildup of pressure, if any at all.

 

[kevinkar]

Hello, everyone.

I need advice please.

It sounds like everything is working normally with a few idiosyncrasies that may or may not point to a possible leak. Of course the topping off on a more than occasional basis would certainly point to that. Otherwise it sounds like your car is working normally though and there's nothing to be worried about other than needing to monitor it regularly.

My '18 R seems fine as well though I DO get the smell of coolant all the time with no real loss of coolant. I do top it off every month or so and I'm sure there's a leak somewhere but there's no evidence of it I can see so I just need to monitor it every time I wash the car (roughly every two or three weeks) and top off a bit as needed. If it drops significantly, it's time to bring it in for a check.

So I would not agree your car requires a water pump/thermostat replacement yet. A check, a leak test, a pressure test, a dye injection to see if leak evidence is somewhere, etc.? Yes, maybe so. If it's a bother to you, take it to a good local shop and see what they can find out.