[Sanidhya mukund]

It has been raining heavily for the past few days here in Delhi. The roads are all waterlogged and the traffic comes to a standstill everyday. Yesterday, I was stuck in a traffic jam while it was pouring heavily and the roads had become like rivers. This was when I noticed that my Mercedes C-class was displaying this warning on the instrument cluster:



This is the warning for low coolant level, so I assumed that the car could possibly have hit some debris leading to a coolant leak. I was sure that the coolant level was okay otherwise because I had it replaced at the Mercedes dealership in April 2021.
However, I found no physical leakage, so I continued driving. The warning disappeared after about 30 minutes, but I still didn’t want to take a chance, so I stopped at a petrol pump and waited for sometime for the car to cool down. I had gone away from the car for merely 10-15 minutes to attend a phone call, and by the time I was back, I was shocked to see that the fuel pump attendant had unscrewed the drain plug and had drained all the coolant! Apparently, he had a word with my driver and they somehow, without my consent, decided that the coolant will have to be replaced!

Since he had already drained all the coolant, I had no choice but to ask them to fill the coolant that was available for sale at the petrol pump. They filled in about 2 litres of green coolant and commented that they have filled it for the time being, but I will have to get it replaced ASAP since this one isn’t suitable for this car. I was already worn out, so paid up and went my way without arguing.

Anyway, since he had commented that this coolant isn’t suitable for my car, I decided to take it to a nearby FNG and get the “suitable” coolant filled. Now this FNG has all sorts of tall claims about being “specialists” in luxury cars and even has a YouTube channel. Now ideally, they should have drained the whole coolant and then refilled it with the appropriate type. However, they did not bother with a coolant flush, and simply drained the coolant from below and filled in 4 litres of pink coolant. However, there already was green coolant in circulation inside the engine, so now my car has a mixture of green and pink coolant.

A little bit of research on Team-BHP tells me that mixing pink and green coolant is a very bad idea because it leads to a reaction between inorganic and organic components of the respective coolants, leading to a coagulated sludge being formed. This sludge can have devastating effects on your engine and the cooling system.
I will now be sending my car to the Mercedes Dealership for a proper coolant flush, followed by filling of the right coolant in the right amounts. I’ll also ask them to see why this warning appeared and disappeared on its own. This was the first time I trusted a non-authorised garage with my car, and is definitely the last.

My takeaways from the above incident are as follows:

1. Petrol pump attendants sometimes can have vested interests of selling their oils/coolants etc. Never let them do stuff to your car and never leave it unattended at a fuel station even for a few minutes. “We checked your coolant and the level is low” or “Your coolant is finished and your container only has water” is a very common thing nowadays. Please ignore them.

2. When choosing an FNG, be VERY careful. Rely on word of mouth rather than YouTube videos or Google reviews. These guys are thugs, they mishandle the cars (mine got damaged) and don’t even have basic mechanical knowledge. Seeing a premium car, all that they care about is milking the customer for money. Any mechanic worth his salt will tell you that one shouldn’t mix two different types of coolants. These thugs on the other hand think that it is okay to do so on someone’s Mercedes!

3. Always know about what colour and grade of coolant your car uses. If possible, carry around a small container of the same.

I do agree that most of this was my fault; I was ignorant about what was going on with my car, but I was preoccupied with a zillion other things.

Recommended further read: This lovely thread by D-BHPians Vishy76 and Vigsom. It covers everything one needs to know about coolant:
https://www.team-bhp.com/news/types-...nd-colours?amp

[shankar.balan]

Originally Posted by Sanidhya mukund

It However, they did not bother with a coolant flush, and simply drained the coolant from below and filled in 4 litres of pink coolant. However, there already was green coolant in circulation inside the engine, so now my car has a mixture of green and pink coolant.

A little bit of research on Team-BHP tells me that mixing pink and green coolant is a very bad idea because it leads to a reaction between inorganic and organic components of the respective coolants, leading to a coagulated sludge being formed. This sludge can have devastating effects on your engine and the cooling system.

This is sad to read. Mixing two types of coolant and over-filling coolant can lead to multiple adverse reactions. Including but not limited to, Coolant Pump failure as well amongst other headaches.

[GForceEnjoyer]

Sorry to hear about this, it must be incredibly frustrating. Draining all the coolant without your approval is shocking! Never heard of something like this before. Mixing coolant, like you rightly pointed out, is a recipe for disaster and will be advised by no competent, self-respecting mechanic. I hope your car can escape any damage to the engine, good luck.

[Jeroen]

I am not sure how this works in India, but in the west going by colour for the type of coolant simply doesn’t apply anymore. You really need to look at the specification of each coolant, the colour is not relevant.

Don’t rely on mouth to mouth, it can be as unreliable as YouTube. Rely on what your owner manual tells you. It will give you a specification (not a colour I would think), next find coolant that matches that specification.

When in doubt what type of coolants have been mixed it is not a bad idea to flush out the system and fill it with the appropriate coolant.

Jeroen

[Sanidhya mukund]

Originally Posted by GForceEnjoyer

Sorry to hear about this, it must be incredibly frustrating. Draining all the coolant without your approval is shocking! Never heard of something like this before. Mixing coolant, like you rightly pointed out, is a recipe for disaster and will be advised by no competent, self-respecting mechanic. I hope your car can escape any damage to the engine, good luck.

Sure is frustrating, man. Actually the thing is, I was on a phone call, waiting for the car to cool down so that I can check the coolant levels. However, during that time, my driver who was standing near the car was approached by a petrol pump attendant and I don’t know what conversation they had, but the conclusion was that they have to replace the coolant immediately!

Originally Posted by Jeroen

I am not sure how this works in India, but in the west going by colour for the type of coolant simply doesn’t apply anymore. You really need to look at the specification of each coolant, the colour is not relevant.

Don’t rely on mouth to mouth, it can be as unreliable as YouTube. Rely on what your owner manual tells you. It will give you a specification (not a colour I would think), next find coolant that matches that specification.

When in doubt what type of coolants have been mixed it is not a bad idea to flush out the system and fill it with the appropriate coolant.

Jeroen

Yes, will be going strictly by the owners manual now. I do understand that colour is no longer a reliable indicator, but the petrol pump guy said that the coolant that he has filled is not suitable for this car, while the garage guy said that he has used a suitable coolant. This has led me to believe that the two not only have different colours, but also have varying chemical compositions.

[lapis_lazuli]

Oh that's shocking to read. But don't worry. It would not cause immediate damage. It needs a thorough flush twice. With the thermostat open. Then the new one and you should be good to go. It hurts when well maintained cars get abused just for the greed. I have always maintained that yes running a quality workshop takes money especially with equipment and good staff. I am willing to spend but not fleeced or becoming victims of greed.

I witnessed similar messy work in another BHPians TJet...it was sent for service at a highly overhyped Noida (not so) FNG and the coolant was a mix of all sorts of matter. Not one component or filters replaced were OE despite easy availability and was charged the same OE rates. A good FNG is a find. You stick to him, pay him more at times, wish him during his festival and your car will be perpetually happy. Again, don't worry. It will be fine after the flush and refill. I never take risk with the coolant and brake pads. It's always OEM. Oil not so much.

[Gansan]

In India the coolant color still matters. It is not that a different color should not be filled, but may be filled only after complete flushing. It is best to stick with the coolant type mentioned in the manual, and it will usually come in the same color.

Get the system flushed and fill appropriate coolant at the authorized workshop asap, don't use the car till this is done. Since it has happened very recently, no damage would have occurred.

I never believe in FNGs. They mostly will not have proper tools for various cars, even bikes, and will use "one size fits all" items. I drive an Alto, and yet I have never allowed a FNG or fuel station mechanic to even open the bonnet! If I had a Mercedes, I won't let them come anywhere within ten feet of my car.

[Sanidhya mukund]

Just opened my coolant expansion tank on a cold engine. Look at the horrendous colour it has taken. This is supposed to be pink in colour:

[pgoyal1996]

I've made it a point to never give away the car to even ASS.
I standby both of my cars the humble Alto and the Vento.
Once, I caught my Alto's windshield broken after getting the car back. Straight away went back to the MASS.
Ask them how did this happen, heard the famous dialogue, "ye to pehle se hi toota tha sir".
I asked him to show me the job card documents, giving him the reason that if it was broken prior to my visit, the same should have been noted in the job card.
His face turned red, and they had to ultimately replace my windshield on FOC basis.

Go out to FNG if known, Go to ASS otherwise but, go with your eyes open.
These guys are their to do business and the exceptional ones indulge into bad practices like these!

[MaheshY1]

The murky color is probably because of engine oil mixing into the coolant. Check if the top layer feels oily. If still in doubt, flush it with water and pour fresh coolant. drive for a while and see if it's again turning brown. If so, then you most likely have a gasket problem. Also, check the engine oil level. If it's leaking, then it should have gone below the recommended level.

A coolant is primarily just water with 2 additives - 1 to increase the boiling point so it doesn't explode the plumbing and 2 is to lower the freezing point, also to prevent tearing up the pipes as water expands on freezing.

The proportions of these additives vary from region to region depending on the climatic conditions. E.g. Middle eastern countries have a boiling problem but no freezing problem while Iceland has a freezing problem but not a boiling problem. Rest assured that any coolant of a reputed brand you buy in India will work in India. I'd not worry much about the color. Besides, any coolant is better than no coolant.

[sagarpadaki]

Here is what I suggest. Drain all the old coolant. Fill the cooling system with just the distilled water and a can of liqui moly radiator flush/cleaner . Drive for around 50 kms. Drain the mixture. Fill in distilled water again. Drive for 10 to 15 kms. Drain out the distilled water. Fill in Mercedes specific coolant. This way you will be sure that there is little or no old coolant mixture left. This process is labor and time intensive. But better than a damaged engihe block

[MBond007]

Originally Posted by lapis_lazuli

Oh that's shocking to read. But don't worry. It would not cause immediate damage. It needs a thorough flush twice. With the thermostat open. Then the new one and you should be good to go. It hurts when well maintained cars get abused just for the greed. I have always maintained that yes running a quality workshop takes money especially with equipment and good staff. I am willing to spend but not fleeced or becoming victims of greed.

I witnessed similar messy work in another BHPians TJet...it was sent for service at a highly overhyped Noida (not so) FNG and the coolant was a mix of all sorts of matter. Not one component or filters replaced were OE despite easy availability and was charged the same OE rates. A good FNG is a find. You stick to him, pay him more at times, wish him during his festival and your car will be perpetually happy. Again, don't worry. It will be fine after the flush and refill. I never take risk with the coolant and brake pads. It's always OEM. Oil not so much.

Hi, can you please share the name of the FNG. It will help others stay away from such incompetent garages.

[Sanidhya mukund]

Originally Posted by MaheshY1

The murky color is probably because of engine oil mixing into the coolant. Check if the top layer feels oily. If still in doubt, flush it with water and pour fresh coolant. drive for a while and see if it's again turning brown. If so, then you most likely have a gasket problem. Also, check the engine oil level. If it's leaking, then it should have gone below the recommended level.

Ouch! I really hope that’s not the case. The car has not run much (30-35k only) and has always only been to the Mercedes dealership. No expense has been spared on maintenance and all fluid changes have been adhered to. This coolant fiasco was the result of negligence on my part and the malicious intent of the garage guys and the petrol pump guy.

Plus I haven’t seen any symptoms of a blown head gasket. No white smoke, no oil consumption. The oil still has good consistency and colour as it was changed only 3600 KM ago.

The colour turned brownish only after green and pink coolant mixed.

[vishy76]

Originally Posted by Sanidhya mukund

Ouch! I really hope that’s not the case. The car has not run much (30-35k only) and has always only been to the Mercedes dealership. No expense has been spared on maintenance and all fluid changes have been adhered to. This coolant fiasco was the result of negligence on my part and the malicious intent of the garage guys and the petrol pump guy.

Plus I haven’t seen any symptoms of a blown head gasket. No white smoke, no oil consumption. The oil still has good consistency and colour as it was changed only 3600 KM ago.

The colour turned brownish only after green and pink coolant mixed.

You haven't blown a head gasket, nor have you damaged the oil cooler. Don't worry about either. This is simply a result of IAT or green coolant (inorganic based technology) and OAT (organic acid based technology) or pink coolant mixing and forming sediments and consequently sludge.

Simply flush the entire system thoroughly. Remove the return line that comes into the expansion tank, and start the engine. Coolant will start coming out. Keep topping the tank up with distilled water. When you see clear distilled water coming out of the return line, you can be rest assured the system has been flushed perfectly. Drain and pour fresh new coolant in.

Next time onwards, please practice discretion and only pour in the specified coolant or distilled water. Even mineral water will do for a short period of time. However, NEVER pour in a separate coolant colour. The resulting reactions can accelerate corrosion in parts like the radiator and oil cooler and cause the seals to behave funny in the longer term. Coolants have been classified into types for a reason. You can read this (Types of Coolants and debunking myths associated with grades & colours) thread for more info.

Thanks

[asit.kulkarni93]

When in doubt, Stick to distilled water. In case of an emergency (like leakages), even mineral water is okay but not for long distances. It can be used to avoid damage to the head gasket and reach the workshop safely. Stick to the prescribed coolant. It's best to get the coolant flushed now and install the correct coolant. Mixing of two different coolants can be hazardous.