Mk7 coolant flush (WHAT A PAIN!)

[mchapek]

So I FINALLY did a 95% (my best guess) coolant flush on my 2015 Golf TDI Sportwagon (the dealership wanted $250 to do it). I've searched and searched both here and the internet, and have found virtually ZERO procedures that actually do a TRUE FLUSH (and I mean a FULL-ON FLUSH like I used to do with my older radiator cars with the old Prestone kit where you hooked up a garden hose to the system while it ran and in just a few minutes you had a complete flush...you know, a 100% flush of all the old fluid and sediment that is in the system).

All of the videos that I did find basically just say to pop the two lower hoses (the big one on the drivers side of the radiator and the smaller one on the passenger side)...both have the little clip you slide up and it locks into the 'unlocked' position, then you jiggle/wiggle/curse until the plastic fitting until it finally pops off, (sometimes taking skin off your knuckles when it happens suddenly) and drain both of those into my radiator fluid drain pan. Those two hoses (which is all you can readily get to) net you about 3/4 of a gallon of fluid. The entire system (according to the VW fluid capacity chart) is 8 liters (2.1 gallons). My car has 63,125 miles on it and as far as I know the fluid was stock (I bought the car 2 years ago, it was one of the buy-back models, had 38,000 on it). The fluid was pretty much orange (ie, a very dirty pink). I'd drain what I could, then using my air-compressor and the radiator vacuum system kit I bought on ebay for around $35 (WELL WORTH IT, works GREAT!) I'd pull a vac on the cooling system (after reconnecting the hoses obviously). It would easily suck back 3/4 gallon (of distilled water, as I'm just flushing the system many times to get MOST of the old fluid out). I'd put the cap back on, drive it a few minutes and re-drain the 2 hoses again, each time getting lighter and lighter colored water. I did that FIVE TIMES, and the last one the water was very diluted, and then I sucked back in 3/4 gallon of undiluted G13 VW coolant. I hope to top it off a few times with more undiluted fluid to get the entire gallon into the system (thus getting the recommended 40% mix of G13 to distilled water).

What I would like to know is just HOW does the dealer service department do a flush? They can't possible do what I did (took the better part of a day and was a huge pain in the you know what). I have Vag-com, and have seen comments like 'don't drain any more than those 2 hoses without Vag-com)...but can't find any procedure using Vag-com to open up places inside the engine that I can't get to when draining to get it all (or even most) out at one time. How is it possible that the Mk7's have been out for YEARS now but NOBODY has posted a good video/procedure on how to do a true flush/fill? My old MkIV has detailed procedures on everything you could possibly want to do...and there is squat out there on the Mk7's. I'd sure love to know how the dealership does this (just what does the $250 at the dealership pay for besides one gallon of G13 coolant)? Certainly they have VagCom, so just what is their procedure? Anybody? How can I get more than 3/4 gallon of fluid out? (ie, how can I get the entire gallon of undiluted fluid IN)?

 

[Cuzoe]

Buy a one day subscription to Erwin and you can download all of the shop manuals, system manuals and wiring diagrams for your car. It's well worth the $35 or whatever it costs and you will have the same procedures a dealer would follow.

erWin Online | Volkswagen of America | erWin Online

erwin.vw.com

What is the interval for a coolant flush? I have not personally looked for it or into it because I have VW care. I haven't seen that on any of my "invoices" after service but I'm not yet at 60,000 I can't imagine the interval is anything that low.

Also worth noting that vag com (VCDS) is not a VW tool. That's not to say that a service center won't have access to one, likely as somebody's "personal tool" because it's faster and easier to use for a lot of basic tasks. But for a coolant flash I would suspect they are using the Erwin manual plus their official tools which have guided functions.

 

[adjat84th]

The vac-fill tool is worth every penny. It helps get coolant in the system through all the check-valves. I was able to get 2 gallons in when putting my new motor in, and then only had to top up the reservoir one time. If I recall correctly, after initial fill, I reapplied vacuum to the system but clamped off the bottom line on the reservoir in order to make sure vacuum was coming through all the bleed lines (that have all the check valves).

 

[Mongler98]

+1 for the vac tool to fill!
Also next time check out thermocure.
It's a royal pita but its actually a proper flush. You have to flush like 12 times though but this will get sediment and gunk out that otherwise is impossible.

 

[740GLE]

Dealers charge prob 250 for just the first step of your process pop the sensor off drain a bit, then vac fill, and call it good.

Also isn't coolant lifetime fluid?

So "VWcare" doesn't really care about your lifetime or the cars lifetime, just the lifetime to get beyond the warranty period.

 

[adjat84th]

Also isn't coolant lifetime fluid?

Maybe if certain hardware has fallen off it could be lifetime. If I was still completely stock, I'd be inclined to flush it halfway between TB intervals if the color was off. Stays nice and purple in my car currently though.

 

[Cuzoe]

@740GLE I'm not under the impression that VWCare is some magical great thing, lol. Certainly wasn't asking for any opinions about it. I'm confused about why you put VWCare in quotes. Do you not believe I have VWCare? Of course the intervals are designed to make sure the car lasts through the warranty period. I feel that goes without saying. Why would a manufacturer set intervals any other way? Even if you don't buy another VW it is not in their interest to support your/my car beyond the intended service life.

That being said, all my services up to 90,000 are paid for, so they get done at the dealer (even though I do some halfway between the VW intervals) and I look at the invoice to make sure they are doing what the interval calls for. I only mentioned it, to the OP, because I could not recall seeing a coolant flush listed as part of any required service. I just checked today and there is a coolant level check at 40k, 80k and 120k... but no flush that I see.

 

[Nuje]

I've never seen a replacement interval for VW coolant, and unlike the Mk4 transmission fluid, it seems to like there's really no need.
The only coolant I've ever "flushed and filled" on my cars has been whatever gets lost during a timing belt change. And the coolant looks as nice and happy-pink as ever, and I'm sure I've read here somewhere people who've tested old coolant and found it to be "good as new".

And to @Cuzoe's point: No mention of coolant flush/fill in the maintenance schedule.

 

[Mongler98]

General rule of thumb on all coolants on all cars.
100k to 150k life on coolant. Within that just drain and fill. Beyond that or contamination requires a flush.

 

[Mike_04GolfTDI]

On my first MkIV TDI, which I purchased new, I flushed the coolant once at about 300,000km and 14 years of driving. That was because the timing belt failed and I had to take the whole engine apart. The cooling system was clean, and nothing was corroded or clogged up inside.

I gave the TDI to a friend when I bought my Golf R and it‘s still running like new. (I rebuilt the engine)

I tend to think flushing coolant is a waste of money and effort, unless you can identify a specific problem with the coolant. The coolant will outlast other parts of the car, unless there’s a leak of course.

 

[oilhammer]

The CR engines tend to overcook the coolant, causing a separation of the additives contained within, which is why they often have brownish sludge floating around in the engine, and why they have a tendency to clog up the heater cores.

So unlike the earlier TDIs, that would/should never ever require any coolant maintenance aside from what you do with normal service like a water pump, these newer ones can sometimes need some extra attention now and then.

Although, if you are patient enough, there is no reason to fret over this. There are about a dozen places on the CVCA/CRUA engines you can access to flush the cooling system with a good ol' garden hose, then do the multiple drain/refill with a proper mix to get it all changed out. But that would only really be required in extreme cases. The heater core in particular can be accessed and reverse flushed all by itself, which is often the main culprit.

 

[r90sKirk]

Agree with Nuge, I do a lot of TB services and IF the engine still has the VW coolant (or equivalent), very rarely do you see any sediment or contamination, and when doing a TB service you get a good amount of coolant drained and then refilled every 100k-130k (depending on the TDI engine).

If however, someone has put a different coolant in the system, then it's a whole different story.

 

[jetta 97]

Agree with Nuge, I do a lot of TB services and IF the engine still has the VW coolant (or equivalent), very rarely do you see any sediment or contamination, and when doing a TB service you get a good amount of coolant drained and then refilled every 100k-130k (depending on the TDI engine).

If however, someone has put a different coolant in the system, then it's a whole different story.

Agree 100% with this .