[#ABTorquey]

Hello Everyone,
I encountered an issue or better to say next issue in my Polo. It is a diesel 2016 model. This happened in last february before lockdown. I had opened my bonnet to refill water for the windshield when I noticed the color of the coolant tank had turned somewhat blackish (Not fully black but almost like mud getting stuck) opened the cap to check and the coolant had changed to something transparent with some sort of muddy colour particles stuck on its walls. (Attaching a picture below). After this, I took the car to my nearest workshop and showed the mechanic but he was not sure about the issue and told it might be rust and it's time to change the coolant. I also contacted the showroom and the technician told to come over and it might be time to change the coolant. But due to some errands in the family, I could not take the car to the showroom. The following week I went to one of my relative's house. There was a steep climb to the house. Naturally, I drove in 1st gear through the climb revving the car. When returning, the coolant warning light came up while coming down the slope. I used the clutch to come down the slope and parked on the roadside. Turned off the engine and waited for 30 mins for the engine to cool down. Bought distilled water from the nearby shop and topped up the coolant prayed nothing would go wrong and thankfully returned without any issue. This happened in March just before the lockdown. Then came the lockdown and the car stayed in my house for almost 2 months. I would start the car every week but the car never left the house.

Finally, in the first month of June I took it to the showroom showed it to the advisor he told it is usual and it is time to change the coolant. I was fine with it I said go ahead and also the annual service to be done. Later he informed that there was a leakage in the coolant tank and it needed replacement and that might be the reason for the coolant level to go down. I said ok and the work was done with an Invoice of 15k.

Now the problem is the car has done a mere 500 kms roughly after the service and the coolant color has started to change again. Can anyone please explain why it has happened.
I don't think it is one of problem in the polo. I remember one time I had seen a polo with the same issue at the showroom and I even asked the owner what the issue was but he had no idea and just saw it when the advisor opened the bonnet for checking (He was there for some insurance claim). I am attaching the before and current picture of the coolant.

Condition before the service was done


Current condition of the coolant




Tomorrow I am taking the car to the showroom to get it fixed. Can someone please help me out by explaining what the issue might be so that I can put a valid argument.

[Traveler]

Couple of things you can check. First, was the coolant actually fully replaced or just topped. It might be that they just changed the coolant in the tank.

Other is more serious, open the oil filler cap on your engine and check the underside. Is it completely black with engine oil or does it have any creamy off-white paste like sticking there. If it has this creamy layer then you have a head gasket leakage and coolant is leaking into the engine oil. The white sludge is a sure shot sign of a head gasket leakage.

Third, it could be a rusted radiator that is Contaminating the coolant. This is not likely to happen unless you have never changed coolant or have used water instead of coolant.

[Fernang]

I might be wrong here, but, you could try posting this in the Polo review and ownership thread for better visibility. I just happened to stumble across your post and unless this gets linked to the main page it will most likely not be noticed.

It's here -
https://www.team-bhp.com/forum/offic...eview-224.html (Volkswagen Polo : Test Drive & Review)

I too am a noob, therefore i might be again mistaken.

[Samba]

Originally Posted by #ABTorquey

Later he informed that there was a leakage in the coolant tank and it needed replacement and that might be the reason for the coolant level to go down. I said ok and the work was done with an Invoice of 15k.

Did they show you the leakage? If there is a leakage on the coolant tank, why will the color turn black? The coolant level will just decrease.
Did they return you the leaked coolant tank? If yes, have you actually found any leak over there?

Originally Posted by #ABTorquey

Now the problem is the car has done a mere 500 kms roughly after the service and the coolant color has started to change again. Can anyone please explain why it has happened.

There might me two reasons-

The radiator is not clean & it needs a proper flushing including the radiator hose. The rust/dirt/muck are all are coming up and getting mixed.

Secondly the engine oil is getting mixed with the coolant. So the head gasket needs to be checked. Do check the morning start smoke of your car & the engine oil dipstick for any coolant mixture or any abnormality.
As you have not mentioned any decrease in coolant level, the chances for this is less, but if it's the case, get it rectified ASAP. This can damage the engine.

[#ABTorquey]

Thank you guys for your valuable replies to the issue. I think the issue is as you have pointed with the radiator and a proper flushing will sort it out. I have told the advisor to do the same and I don't think there is any leakage or engine oil getting mixed with the coolant as it appears to be rust and other particles. If it would have been the engine oil then it would have been complete brown I guess. Although I have told the SA to check the same.

Please pardon me for any mistakes in the post or thread as I am a mere beginner on the forum.

Thanks All,
AB

[Jeroen]

As the other members have pointed out, make sure you have no leaks. If the cooling liquid level remains the same, (check when cold) you should be fine.

Cooling liquid does need refreshing every now and then. Even the long life version rarely last more than 5 years or 100.000km. Check what your owner manual says, but I would not be surprised yours is overdue.

Cooling liquid these days is a pretty advanced type of liquid containing all kinds of different chemicals. Obviously the purpose of a cooling liquid is to cool! But it does so in quite a harsh environment, different materials, rubber aluminium, steel, different temperatures etc. So a lot of these chemicals are necessary to prevent any kind of corrosion and or detonation of the cooling system components.

But it does mean at some point in time, the cooling liquid just can’t cope with it anymore. A combination of deterioration of the cooling liquid, some corrosion and wear and tear is likely to also darken the colour of the liquid.

Good luck

Jeroen

[Kosfactor]

Over heating + discolored coolant in general needs a new headgasket , recently happened to a Ford Figo that we know of. Rust in coolant system is a possibility on older cars, this one is a 2016 car.

Please do let us know what happens once you are back from service.

[nirmaljusdoit]

Cooling issues are common with VAG vehicles. As the system ages, problems with coolant hoses, flange etc start popping up.

Coolant should be red and remain red.Any change in the color indicates a problem ranging from hoses to flange failure and leaks and disaster when head gasket fails.

Insist on the dealer removing the whole system thoroughly and checking everything one by one. Coolant system issues requires dismantling of the entire system and checking is time consuming and difficult to do but the safe way forward for you in this case.

Also have you seen your old coolant bottle and where was it leaking from ?

[AutoSphere]

Originally Posted by #ABTorquey

I think the issue is as you have pointed with the radiator and a proper flushing will sort it out. I have told the advisor to do the same and I don't think there is any leakage or engine oil getting mixed with the coolant as it appears to be rust and other particles. If it would have been the engine oil then it would have been complete brown I guess. Although I have told the SA to check the same.
AB

I am surprised that the dealer did not flush the radiator/entire cooling system when they replaced the coolant & the tank in June. In my opinion, you should take it up with the senior management at the dealer.

Do you have a sample of the coolant and can you check if it is oily? Maybe pour it in a glass and check if any oily substance is floating on top?

Hope they have diagnosed the issue correctly this time and good luck !

[libranof1987]

Originally Posted by #ABTorquey

I think the issue is as you have pointed with the radiator and a proper flushing will sort it out. I have told the advisor to do the same

If you want to get the radiator flushed, find a dedicated radiator repair shop. They do a terrific job in cleaning all the tubes, straightening the fins and the overall servicing of the radiator. I doubt the SA is equipped to clean the radiator half as well, or the inclination.

That is, if it is indeed the root and only cause. As others have suggested, you might have a bigger problem at hand than just a choked radiator.

[landcruiser123]

I'd pray it is a dirty cooling system (and not a blown head gasket.) A proper radiator flush can solve that. Also have the mechanics to check for any disintegrating hoses.

I doubt it's a leaking radiator. Doesn't hurt to continuously monitor color of the smoke, engine oil, and coolant levels periodically.

[vishwasvr]

This is a common issue with the older VW cars. Have the coolant system flushed with radiator flush additive. You'll also have to manually clean the coolant tank as well. Observe for any leaks and then go ahead if none.

[vishy76]

This might be an issue with either your head gasket or the oil cooler assembly. These are the only two places in the engine where coolant and oil circulate in close proximity to each other and have high chances of mixing up.

If you arent facing under compression and degraded performance, I would place my bets on the oil cooler. Getting it changed and flushing the entire cooling system along with addition of fresh coolant should do the job. A bad head gasket usually does cause low compression as well and sludge under the oil cap as said by members before. If you aren't facing either, I would say it's the oil cooler you need to examine.

[pganapathy]

I had a similar issue with my 2006 Fiesta a year or so ago. The guys told me they essentially need to drain out and clean the coolant tank. Ideally you should also flush out the radiator. The gunk that is in there is circulating. They did it by emptying the tank and filling and emptying it out with water a few times will running the engine. Not a very difficult task if they know what they are doing.

[prateekchanana]

I had the exact same issue in last month in my 2014 Polo diesel. The coolant had changed color but I got the car serviced from an FNG booked through Gomechanic as the company service centre my car is serviced form is in Ghaziabad and they were not ready to pick the car from Delhi. The service became due in first week of April and I wanted to get it serviced as soon as lockdown lifted in Delhi.

Coming back to the issue, my coolant also changed color before the service and the FNG told me that they will flush the old coolant and replace it with new. They did the same but post service within 3 days the coolant level became low again and color started changing little bit. I sent the car to the garage again and the did a top up and asked me to drive.

Again after 3 days the coolant level light popped up and this time I went personally. They topped up the coolant in front of me and it took us more than 3-4 hours to find the issue. He removed attached all the connections properly but the coolant was still leaking form somewhere in very small drops and we could not find from where.

However instead of changing the whole container he just replaced the cap of the tank from a vento which had come for service and it stopped leaking. He arranged a new replacement cap for me and as per his explanation, the inside of the coolant cap has some pressure sensitive parts which were damaged in my cap which caused the coolant to leak due to some air pressure issues. However after replacing just the cap the car is running fine for over a month now without any issues.