I'm also one of those "slowly losing coolant" people

[beanbag]

2018 Golf R, almost out of warranty.
I don't remember ever having to top off the coolant until last November. (Maybe during one of the car inspections / repairs along the way somebody "topped up all the fluids") Anyway I took it to the dealer, they pressure tested it and found no leaks. Oh well. Now 4 months later it is again down to half way between Max and Min. Took to dealer again to pressure test and "look around" and they didn't find anything.
Here's what I see as options at this point:
0) No, I am not going to jack up the front of the car and take off the panels and crawl around underneath. Not in the mood
1) Pay a local shop around $200 to pressure test (again?) and make THEM get the car on a lift and look all around. Maybe if they find some crusty residue I can go back to the dealer with that picture.
2) Buy some kind of boroscope / camera on a stick and use that to have a look around.
3) The dealer offered that if I drop off the car for 2+ days, they can take off parts to have a more thorough look-around. (Something about an "internal leak".)
4) Just ignore it and top off the fluid once every few months. Hopefully it won't get worse. If it fails outside of warranty, oh well.

BTW, no coolant detected in oil, no white smoke, no obvious coolant smell.

 

[tmw2442]

About a dixie cup or two year is normal moisture loss since the mk5 days. If is passes a pressure test...and you don't see a dried chalk white film anywhere or after you drive it pop the hood and sniff any sweet coolant smells?

Just because it "passed" "a pressure test", in stealer-ship speak that could mean...we dove it around for 15 mins until is was warm, and then unscrewed the expansion tank a couple turns and heard a PSSSHHHH and so.... it has the ability to pressurize, and the leak is small if any.

Without a code in the system or a visible leak, a dealer can't get anything done via warranty. The joys of guided fault finding.....which means if the diag computer didn't tell them to do it...they can't troubleshoot it...or the problem "doesn't exist" to them. You're just an arsehole customer they will try to rid themselves of as quickly as reasonably possible . The computer says pass, and that's all my boss told me I can do...sorry about your luck...

It's going to be difficult to troubleshoot. The system isn't completely sealed. Could be a expansion tank cap, the plastic coolant union by the turbo (part # 06K 121 143), a small water pump leak, or any combo of multiple parts not sealing 100 percent.... but you should at least smell it, and/or see evidence of it on the undertray or see it pooling near the turbo heat shield( follow the return line from the expansion tank to the rear of the motor near the turbo). If....there is an actual leak of any moderate amount.

EMD makes a couple replacement aluminum parts for some of the plastic in the system.... https://www.emdauto.com/collections...er-for-mqb-2-0t-e888-3?variant=40092390850743. Not super common on low mile cars, but worth a check.

Probably, have more success at an established Independent Euro shop than with a dealer, generally. Opinion/Experience.... The only thing a dealer will want to do with you is give you less than trade in value for your car, and kindly out of the goodness of there hearts will upgrade you into a new 24 R, for only 10K over MSRP....

 

[beanbag]

The dealer's pressure test was 2 bar, 45 minutes

 

[tmw2442]

Believe what the tell you...and it's within spec.

Passing a VAG test "spec" doesn't mean something isn't wrong or marginal.

So they pressure tested it to 30 psi and it continued to "Hold" 30 psi for 45mins or was the leak down for that specific time within, VAG spec?

I am going to assume they did the minimum.... just pressurize it (on a tester) and walk away, then came back 45 min later just looked at the numbers on the guage and it was within green(ops checks good, per spec).

or

Hopefully...if they are half good at their jobs they pressurized it and looked for visible coolant leaking out of common places. Then didn't see any coolant actively leaking during the test.

If you trust the dealer and the test, then the missing coolant is within the dixie cup or two a year "normal" evaporation loss from the system over time

Or

Having your grey matter clouded by an unfounded/supported emotional reaction to a car going "out of warranty" and now you are being sensitive to something being wrong, and what IF...ING yourself.

Or

You can believe what you have seen(being excessive or outside normal...), if all your are saying is accurate with minimal emotional embellishment of the coolant situation. I would say it's losing coolant on the high-er side of normal to slightly abnormal.

Pick your poison...you asked the internet for help/opinions. And you'll have to make a decision on which path to go down from here. Good Luck...Right now without more data, We are at a solid internet "MAYBE"...there is an issue.

 

[Pineapple]

I addressed my issue with this thread:

https://www.golfmk7.com/forums/index.php?threads/burning-coolant-on-turbo.442668/#post-8043041

It's an easy check to see if that plastic adaptor has burnt crap around it. Just need to lean over the front and shine a light.
Not sure how much research you'd done so far but I've also seen people reporting pressure tests not finding leaks that only open up once the system is warm.

 

[BudgetPhoenix]

My slow coolant leak was also the turbo coolant line hose adapter. At first it was slow enough that it would burn off before hitting the ground and just looked grimey back there. Just fixed it last week with the EMD billet version. No more leaks!

 

[scrllock]

If you want to feel better, go to harbor freight, buy a universal pressure tester, pump it up to 1bar and see if it loses pressure and you find a puddle under the car. If you don't, congrats, you've passed the service manual test for a leak.

If you're only halfway down to min after 4 months, you have an extremely small amount of coolant loss. I would absolutely not worry about it.

 

[The Fed]

Could also be a slightly leaking heater core or hose connection, but I would check the turbo coolant jacket seals and lines first. Are you getting the odor of coolant inside the car? All would cause that. My MK4 after-run pump oozed coolant from one of the hose connections, and my MK5 lost a little coolant without finding a leak. From comments by other owners, it seems normal. I just check it when I check the oil and brake fluid levels. If I need to add a little every few months, I don't consider it a big deal. Many owners need to add a little oil between changes. If the overflow bottle gets very low in a short period of time, then I would worry about it.

 

[Al_in_Philly]

Now 4 months later it is again down to half way between Max and Min.

That is pretty much where the coolant level should be. When you fill the reservoir up to max, with the engine cold, it will likely begin to expel a bit of the fluid when the engine (and the coolant circulating within it) gets hot, but not so much that when the engine has cooled that your reservoir has too little coolant to do its job. This expulsion of excess coolant through the heating cycles is quite gradual, in your case, taking 4 months to reach the median level. My guess is that it will keep pretty close to this level for a while, though evaporation through the overflow hose will still slowly leech some of the fluid over time. Remember, you should change all of your coolant every three years, regardless.

 

[steinfeld]

I have the same problem. Just have to top off the coolant every year.

 

[tmw2442]

Make sure you are consistent when you are checking your level in the tank...if 1/2 the time the car is cold and the other half you just drove it...vica versa...you are going to see a greater delta between levels in the overflow.

 

[aloha_from_bradley]

Ahhh... the good ol' coolant story.

 

[Mk_GTI]

My 2018 R had the water pump replaced at 29k miles. At 53k now and get the gradual coolant loss over six months or so and the coolant odor often. Dealer rechecked a month ago and said it's fine. I should not be smelling any coolant odors at all.