Dirt in coolant expansion tank?

I was looking inside my coolant expansion tank and I saw at the bottom what appeared to be dirt or some kind of crystals. Anybody else have that? I'm wondering if it's dirt and if so how it got there or if it's some kind of anti-corrosion crystal additive. I just bought this car and I don't feel like doing a coolant flush. The coolant otherwise looks clean.

What colour is the coolant ?
Could be that it was topped up with the incorrect product which will cause precipitation of brown gunk.

I have noticed when I open my expansion tank there was a small amount of what appeared to be sand at the bottom of it. Not sure how that got there, but coolant has been flushed since during normal maintenance.

I would flush it because that doesn't sound right. My 98 Beetle never had the coolant touched until 100,000mi when I had the timing belt changed with the water pump. Even at 100,000mi there wasn't anything in the bottle and the bottle and coolant looked as good as the day when the car drove off the new car lot. VW coolant is best left alone for at least 100,000mi. Even then it's probably fine but you have to replace the water pump so why not flush it at that point.

The color of my coolant is light red as it should be I believe. And it's clear like I said, other than the "sand" at the bottom of the expansion tank. Turbosprezarka, you seem to have that same problem, interesting. The fluid level was too high when I bought the car so last night I sucked some out to bring into the correct range. That's when I noticed the gunk at the bottom. The car only has 24K miles so I think it's premature to do a coolant flush, but maybe I should remove the expansion tank and clean it. Is a VW dealer the only place to get the proper coolant, or is there an equivalent in one of the auto parts stores?

alecp said:

What colour is the coolant ?
Could be that it was topped up with the incorrect product which will cause precipitation of brown gunk.

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Have you actually seen this happen or are you just speculating? I hope it's just some soft precipitation that wouldn't harm anything.

Maybe it's sand from the engine casting? Could that even be possible?

Mine looks like that, I put Bars Leaks powder in it to stop a heater core leak (worked great). So that may be what you are seeing, and may be why the prev owner got rid of the car?

I had a look again tonight and I even took a picture, but it seems like this forum doesn't allow attachments. There's two kinds of debris in the expansion tank, one that kind of looks like the residue of Bar's Stop Leak and the other that consists of larger, black chunks, some of which float. I'm planning to remove the tank tomorrow, clean it out and examine the debris in more detail. It's hard to imagine that this car, being so new, would require a stop-leak.

uploade the pics to your photo section, then you can link them. click on "Photos" and then login, then upload...

Could this be an oil related failure? (ducks)

The proper speced vw coolant can only be had from dealers or from online vw/audi parts dealers. You would want g12(pink) or g12+(purple) coolant.

Honestly 24k seems right on time for a coolant flush if you are finding contaminants in the system. I mean better safe than sorry right?

I have it too. Not really in the coolant itself but at the top of the expansion tank on the inside, looks like black crystals etc. Still on the factory coolant.

Diesel Addict said:

Have you actually seen this happen or are you just speculating? I hope it's just some soft precipitation that wouldn't harm anything.

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When I bought the wife's Passat it had been topped up with the wrong coolant.
Used that to chisel the price and ended up doing a flush and replacing the expansion tank as it was impossible to clean.

mickyTDI said:

I have it too. Not really in the coolant itself but at the top of the expansion tank on the inside, looks like black crystals etc. Still on the factory coolant.

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Interesting, your case seems pretty much the same. I have these black chunks on the inside walls of the expansion tank above the coolant level too, but most of them are in the coolant because like I said it was overfilled somewhat when I bought the car. For now I'll just clean out the tank and see if more debris accumulates there. If so I may do a complete flush. Hopefully it's mostly just soft precipitation.

The picture I took is on my home computer. I'll upload it later.

So after removing and draining the expansion tank as well as reading the owner's manual it definitely appears to be a case of someone topping off the cooling system with the wrong coolant. I was wrong about the 2 types of debris. There's only one type (the black chunks), just different sizes. Also as you can see the coolant isn't as clear as I thought. It was clear in the expansion tank, but not in the lower sections of the cooling system like in the hose that connects to the tank.





So I'm definitely going to do a complete coolant change. After reading some of the posts on this board, I see there's some disagreement about which coolant is best and I'm not so confident about the G12 coolant because of the failures that some people have had. I think I'll stick with Zerex G05 which is what I've been using in my Mercedes, but I wonder if it can react with any leftover G12. I better get rid of all of it.

I read there's a drain plug on the radiator, but is there one on the engine block as well? Any tips on doing this procedure? I've done it many times on various Mercedes but I'm new to VW.

Please use only G12 in your car. What failures are you talking about? I have not seen one G12 related failure ever. Yes, failures where G12 was mixed with something else, but never a failure where the G12 system was maintained properly. If you have one that's been documented, please prove me wrong.

Or are you going by my current problem? I'm gunna blame that on a little rubber o ring, which is 6 years old, and has 173,000 miles on it.

You should do the coolant migration weep hole mod.

-Jason

Agreed, where are these g12 related failtures you speak of? Also, I dont think there is a drain plug but I could be very wrong.

If you are going to be doing the switch you should completely flush the system with water to get out all the g12.

There is a drain plug dave, on the bottom of the radiator. I forget which side it's on though.

-J

From my brief search on this board there is a radiator drain plug, but I haven't found any reference to an engine drain plug. Mercedes have both of them and they make it easy to get rid of all the coolant. There was some mention of G12 related failures in these threads:

http://forums.tdiclub.com/showthread.php?t=58302&highlight=zerex+g05+coolant
http://forums.tdiclub.com/showthread.php?t=35098&highlight=zerex+g05+coolant

A lot of people swear by G12 though, so it's probably a good coolant but apparently as long as the system is completely flushed any coolant would do. Zerex G05 is an excellent coolant by the way which has been tested extensively and used by Daimler-Chrysler and Ford with excellent results and it's supposed to provide superior metal protection. And I know from personal experience that it doesn't precipitate anything when it comes into contact with the green stuff!

Anyway, I'm just trying to find out if there's a drain plug on the engine. I'll take a look tomorrow and maybe I'll find out.

funny. no mention of g12 failures in either of those threads . what is your deal? hmm... i wonder why your coolant is looking a little brown... maybe it's time for a pontiac...

Shell DEX-COOL has an VW/Audi Approval

As seen on their product sheet under Approvals

• Volkswagen/Audi G-12

http://www.shell-lubricants.com/products/pdf/Dexcool.pdf

I did not see a similar approval under the Zerex page.
http://www.valvoline.com/products/Zerex%20G%2005%20Antifreeze.pdf

Take this for what it is worth. An Approval is an Approval.

Diesel Addict said:

From my brief search on this board there is a radiator drain plug, but I haven't found any reference to an engine drain plug. Mercedes have both of them and they make it easy to get rid of all the coolant. There was some mention of G12 related failures in these threads:

http://forums.tdiclub.com/showthread.php?t=58302&highlight=zerex+g05+coolant
http://forums.tdiclub.com/showthread.php?t=35098&highlight=zerex+g05+coolant

A lot of people swear by G12 though, so it's probably a good coolant but apparently as long as the system is completely flushed any coolant would do. Zerex G05 is an excellent coolant by the way which has been tested extensively and used by Daimler-Chrysler and Ford with excellent results and it's supposed to provide superior metal protection. And I know from personal experience that it doesn't precipitate anything when it comes into contact with the green stuff!

Anyway, I'm just trying to find out if there's a drain plug on the engine. I'll take a look tomorrow and maybe I'll find out.

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I've seem it and it appears to be some rubber from the hoses. Under a scope it's squishy and it is flamible. That's my guess. Anyway it's SUCH a small amount it won't harm anything. Don't freak out about it.

jasonTDI said:

I've seem it and it appears to be some rubber from the hoses. Under a scope it's squishy and it is flamible. That's my guess. Anyway it's SUCH a small amount it won't harm anything. Don't freak out about it.

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Agreed, some nice crap came out when I flushed the system while doing a TB a few months back... Nothing to get all excited about.

burpod said:

funny. no mention of g12 failures in either of those threads . what is your deal? hmm... i wonder why your coolant is looking a little brown... maybe it's time for a pontiac...

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Here is one "failure" mentioned:

Quote:
If there is one thing VW is good at, it is the quality of its service fluids. Not cheap, but the quality is excellent.


So true. The VW coolant will keep your cooling system working trouble free until something goes wrong. I have not yet seen the superiority of G-12 coolant.For example: My wifes TDI seeps the G12 out the water pump since 30,000 miles and my neighbors VR6 had the G12 run out all over the garage floor, when the water pump let loose at 35,000 miles. The radiator just went out at 43,000 miles. The car now has Zerex in it.


I put 150,000 Dex-Cooled miles on my old Audi 5000 Turbo and never had a problem with the coolant system (put Dex-Cool in it when I replaced the water pump and radiator). I have 40,000 Dex-Cooled miles on my current Audi and no problems either (the head gaskets still seep like they did 40,000 miles ago and I'm pushing the envelope on that one).

I guess, I'm lucky with Dex-Cool

I understand that G-12 is a good antifreeze, but there are still failures out there. At this point I still feel that the specific fluids and fasteners that VW is using is just a way to make money down the road.

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What's the word? Anecdotal? A person should not base their dislike of G12 on this persons experience. I haven't checked the other post though, but I'm guessing that the "evidence" will be just as useless.

Total BS. Besdt coolant I've ever seen. Stuff happens. Bad parts here and there and none of those issues has anything to do with the coolant it's a parts related failure.

OK, I found that Autodiesel says that there are water pump seal failures due to the type of coolant.

Everyone else disagrees, but there are people that believe there are coolant caused seal failures.

jasonTDI said:

Total BS. Besdt coolant I've ever seen. Stuff happens. Bad parts here and there and none of those issues has anything to do with the coolant it's a parts related failure.

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I concur. I'm just trying to find what failures they were talking about. Once that is known, they are seen to be totally BoguS.

The GrandPrix will be home this weekend... You guys will love the horror that lives under the radiator cap.

-Jason

burpod said:

funny. no mention of g12 failures in either of those threads . what is your deal? hmm... i wonder why your coolant is looking a little brown... maybe it's time for a pontiac...

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What's your deal? I'm just trying to get some help here and thus far I haven't done anything to the Jetta and that's the way I bought it. But having had a dozen cars, many of them new, I know from experience that each manufacturer's fluids are not always the best choice. They're usually adequate and will get you through your warranty, but they're not necessarily the best choice if you want to rack up 300K miles on your car without too many problems. Take it FWIW.

From what I read G12 is of the OAT type, and tests have shown water pump damage after 100K miles with such a coolant. Zerex G05 is a HOAT coolant and it seems to offer better long term protection. I guess VW designed the system so that the water pump only lasts as long as the timing belt, but if the metal on it can get damaged from using an OAT coolant, I wonder what can happen to the rest of the cooling system. Again, take it FWIW.

I probably wouldn't flush the coolant just for a few black chunks, but the coolant appears brown instead of pink as you can see on the last picture. According to the owner's manual this happens when G12 is mixed with another coolant and it's recommended to do a flush in that case. I'll let you guys know tonight if I find that engine drain plug.

Why would you be running your water pump beyond 100,000 miles? It's driven by the timeing belt... and should be replaced every 100k.

-Jason