Volkswagen Passat Forum banner

My total coolant flush attempt!

5K views 28 replies 11 participants last post by  RGeo13 
#1 ·
Hello all, I'm a new passat (2002 GLS 1.8T B5.5) owner and forum member, and I first just wanted to say thank you to everyone who posts here. There has been a lot that I've taken from this site in the 3 short months I've owned my passat.
Anyway, long story short, I bought the car at an amazing price because it had a bad oil cooler. Got it fixed along with several other things for $1000. Well, the STOP CHECK COOLANT has come on three times since then (around Christmas 2014). Took it back to mechanic and he flushed more each time. It's been about a month since the last flush, and the coolant is still dirty. The gunk also rotted the cap, and now it isn't sealing. I bought a whole new reservoir and I'm just going to swap them when I have everything drained. And, the mechanic didn't put G12 in. So, rather than paying $180 to have the entire system flushed and filled with G12, I've decided to tackle it on my own. Planning on doing it this Friday. I've already searched about every key word I can to get the best threads, and I have 5 currently bookmarked. Went out today and located everything that I'm going to need for Friday, and I'm feeling good about it. Couple questions about it:

I too have noticed very little heat, like many of the members on here. Read that it is a clogged up heater core. When I flush the entire system, would that clean it out, or should I flush it separately as well?
Also, how many flushes does it usually take for the system to come out clear?

I'm sure I'll have more questions before Friday, so I'll ask when I think of them. Thank you all so much!
 
See less See more
#3 ·
#5 ·
You'll get better flushing if you remove the thermostat for the whole process. To drain the system disconnect the thermostat housing from the water pump and pull it lower than the radiator.
 
#6 ·
The mechanic didn't use G12? egaads...

Draining the coolant post-thermostat is easy.. just open the drain on the radiator.. the messy part is getting what's in the heater core/engine block.

There's a drain in the hard water pipe underneath the intake manifold.. or like ^^^^ said, you can just yank the thermostat out.. either way it'll be messy.

Reverse flushing the heater core should do you a bit of good, if not..well.. at least winters over now lol

When I did my coolant flush I used my garden hose-- I have pretty good water pressure at the house so I was able to get quite a bit of gunk outta there.. then before I sealed everything up I ran some distilled water through everything to get some of the garden hose water out then sealed everything up

let us know how it goes!
 
#7 ·
Definitely reverse-flush the heater core till it's clean.

Next disconnect the radiator hoses and use a garden hose to flush out the rad, and reconnect after it's clean.

Then remove the t-stat like suggested above. Also you can splice in one of those Prestone flush kit garden hose T fittings in the heater line with the bleed hole to make things easy (you can just unscrew the cap to let air escape as you fill the system again and again).

Then fill with plain water, run it a bit, and then drain. Repeat until the water draining out is clear.

I wouldn't bother filling with distilled water and draining (though that certainly wouldn't hurt) before adding G12 mixed with distilled water.
 
#8 ·
Thank you all so much for your replies!
Probably am going to try to avoid taking off the thermostat, even though everything that's been posted and what I've read says that it makes it much easier.
Planning on using my garden hose to flush, and then distilled water last and on the fill. Also am planning on putting a little bit of Dawn in to get the remaining oil out, and I have a bottle of the radiator cleaner stuff from the auto parts store that I'll run through once. Also, picked up some CLR for the heater core. Hoping all goes well, I'll definitely post how it goes! Thanks again everyone!
 
#9 ·
Don't use dawn or anything else that would foam.

You can use any low foaming detergent like purple power or simple green if you like. Let it come up to temp to help thin whatever oil is in there. Then flush with water. Note purple power full strength is corrosive to aluminum after about 10 min. You will dilute it of course, but don't let it sit in the engine for days.

If you want to help the core unclog, let some CLR or citric acid sit in there for a few hours. Start with a weaker solution and increase the strength and shorten the soak time as you observe what comes out. Pass everything through a fine sieve to keep track of your progress.

Take out the tstat and it will be faster (albeit a little messier).
 
#10 ·
If you leave the tstat in, you'll have to bring the motor up to temp to get it to open, then let it cool off a bit before draining and filling again.

Remove it, and you can let it run for a few minutes, then drain before it gets too hot, and repeat much more quickly.

You will already have the cooling system drained, so it won't be that messy. Remove the cover, pull the tstat, and replace the cover. It's two bolts.
 
#16 ·
I too had no heat. what I did was I back flushed the heater core. Its really simple. Find the 2 hoses on the upper firewall. They are next to the battery. Disconnect both hoses. Then hook up a garden hose to the passenger side hose and blast fresh water through the passenger side intake. You probably should connect a hose to the driver side connection so you can divert the flush water away from the engine and away from the car. After doing this, reconnect all hoses and refill the coolant system with the RED ANTIGEL REFRIDIGERANT. You can now get this at Advance Auto Parts in a concentrated formula. You don't have to buy it from VW exclusively. Do not use anything but the proper coolant. If you use regular antifreeze, it will gel up and totally mess up your car. After doing this procedure, I have heat and my wife and kids are happy. Hit me back if you need any help doing this.
Ken
 
#18 ·
Sigh, I thought the same thing when I saw that bucket. Did they do the flush with a machine, or was it some shop guy with a garden hose?

OP, in the one month since the shop flushed your cooling system did your oil get low? If so, you need to find where the oil is going or at least rule out that its mixing with the coolant before you flush your cooling system.
 
#19 ·
The mechanic I took it to is literally the best reputed mechanic in the area. He has rechecked the oil cooler and everything.
Strangely enough, the first official flush came out clear. Then I checked the hoses and they were caked in that sludge. Went to WalMart and bought a $6 hose scrubber brush thing and cleaned out every hose! Starting to look good, no more goop! Thanks for all the help guys!
 
#21 ·
Well, that's good to hear!! Progress! So, the goop was from your hose cleaning.

Oh and by the way, I read earlier some talk about filling the system with the G12 already mixed with distilled water. It is best practice to add the correct amount of G12/G13 for your engine and the add distilled water to fill. This yields the best mix as there will always be some water remaining in the engine after the flushing.
 
#22 ·
Alright, so after nine loooong and disgusting hours, I finished! Ended up taking off my hoses and scrubbing them with my $6 pipe cleaner and got the sludge goo stuff out!
Changed the reservoir along the way as well. Finally, PINK!!!!

The pic of the hose is what every single hose looked like on the inside. The whole way throughout the system. Totally gross.

The pic of all the jugs is the stuff from the flushes. The lest is the first, to the right being the last. Lots of chunks, which is bad, but good that they are out!

And, the new pink coolant! So pumped!
 

Attachments

#23 ·
Which is why draining from that tiny radiator petcock and flushing with the thermostat in place will not do the job. Regardless of what the write-ups or the manual says.
 
#24 ·
when the system is contaminated . the manual assumes that no idiot has touched the system . this thread is about that , not proper maintenance . 135,000 miles and excellent heat and pink jug . i wouldn't bother power flushing it as it works fine and will as long as its maintained properly . now , off to change my oil ..
 
#26 ·
I wish there was a fellow Passat owner who has done the radiator/heater core flush in the Seattle area that could assist me with it, I simply have no patience and afraid I would end up doing it wrong. My car has about 135,000 miles on it, the heater takes forever to warm up, but it would be nice to be able to flush everything and get heat when I want it. ;)
 
#28 ·
True but for me anyways I simply don't know anything about the internals of the car and would rather pay someone to assist me who lives in my area than tackle it myself, even with instructions. This way I know it's done right. Trust me I am interested in watching how it all works and helping but for me at least, it's easier to have someone help out who knows what they are doing.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top