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Odd coolant color

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Radox   
Fri Feb 12 2021, 01:21pm
Joined: Aug 27 2019
Member No: #4044
Location: Bad Bergzabern
I seem to finally have fixed all of the problems with my C6, but yet today, a new one has arrived, and it can be SERIOUS.

I lose a bit of coolant every now and then over the past 2 years. It's not much, about 1cm per month, and sometimes there is white residue over the radiator cap (I guess it's overflowing at times).

However, when I checked today, I dipped a white wooden stick into the coolant and it came out dark brown and sticky. Is this a sign that the coolant is mixed with oil and I have a blown head gasket, or is this normal? I changed the coolant about 2 months ago. Can it be a gearbox leak?

Sorry if there's already a topic on this issue, but I've been unable to find it.
Fraunie   
Fri Feb 12 2021, 03:25pm
Joined: Dec 09 2018
Member No: #3763
Location: Stockdorf
Which coolant did use you use when you changed it two months ago?
Radox   
Fri Feb 12 2021, 05:32pm
Joined: Aug 27 2019
Member No: #4044
Location: Bad Bergzabern
I don't know, they changed it at Citroen Reutlingen. I assume it's an approved Citroen coolant.
Fraunie   
Fri Feb 12 2021, 06:33pm
Joined: Dec 09 2018
Member No: #3763
Location: Stockdorf
If you mix two different types of coolants you can get any kind of color...
cit-rotti   
Fri Feb 12 2021, 09:34pm
Joined: Dec 03 2018
Member No: #3753
Location: Bayern
Hi,
Oil in the cooler water is actually always a muddy slush.
You should check the following:
Is there also water in the engine oil ??? The engine oil then turns white / gray instead of black - depending on the amount of water.
Press the cooling system down with approx. 1.5 - 2.0 bar - the pressure must not drop.
If it falls off, it must be checked where the water leaks.
If there are no externally recognizable traces of water, the water in the area of the cylinder head / EGR / heat exchanger transmission etc. is lost.
A pressure loss test will probably give more information.

If the pressure test remains stable, I would change all of the cooler water and then rinse it several times with water - then refill it.
Greetings Wolfgang
Radox   
Sun Feb 14 2021, 02:13pm
Joined: Aug 27 2019
Member No: #4044
Location: Bad Bergzabern
Thanks for the info, Wolfgang. I checked the oil and it is perfectly black. No signs of other colours. I hope this means that I must not scrap my car...

I think my water escapes from the radiator cap. I had this cap replaced a while ago with a new one, but the car continues to "spit" water from the cap. There are white drops over the reservoir every 2nd-3rd day when i check. This might be dues go combustion gases from the cylinders entering the water circuit and pushing the water out of the cap?
Fraunie   
Sun Feb 14 2021, 04:13pm
Joined: Dec 09 2018
Member No: #3763
Location: Stockdorf
I had the same phenomenon with a new cap. I changed back to the old cap and everything was fine....

Maybe the new caps have a different valve?
cit-rotti   
Sun Feb 14 2021, 08:32pm
Joined: Dec 03 2018
Member No: #3753
Location: Bayern
Radox wrote ...

This might be dues go combustion gases from the cylinders entering the water circuit and pushing the water out of the cap?


Hi,
the radiator cap opens at around 1.4 bar. This is only achieved at very high temperatures.
If exhaust gases are pressed into the cooling water, this pressure is exceeded more quickly.
There is a test for this - it is often used to check that there are exhaust gases in the cooler water. You should perform this CO-2 test carefully.
So that it can be ruled out that the cylinder head gasket is defective.
Greetings Wolfgang
Cisco   
Thu Feb 18 2021, 09:52am
Joined: Sep 10 2013
Member No: #1429
Location: Glasgow
Sounds like your oil filter heat exchanger is failing. Hope this link will work

- Click Here -
cit-rotti   
Thu Feb 18 2021, 02:19pm
Joined: Dec 03 2018
Member No: #3753
Location: Bayern
@ Cisco
a very good reference
This may explain the contamination of the cooling water with oil - but not the overpressure.
A Co 2 test would therefore be very useful.
Another simple test would be to test the pressure build-up in the cooling system.
Instead of the cap on the expansion tank, a cap with a pressure gauge (0 - 5 bar) can be screwed on.
During normal driving, a value above 1.2 - 1.3 bar is never reached. With significantly higher values, exhaust gases are the cause = defective cylinder head gasket or small cracks in the cylinder head.
Greetings Wolfgang
Cisco   
Thu Feb 18 2021, 06:39pm
Joined: Sep 10 2013
Member No: #1429
Location: Glasgow
Hi there, The OP does not mention any over pressure.

If one of the head gasket fire rings on one or more of the cylinders is passing combustion gasses to the cooling system them this will become obvious with heavy overflow at filling cap. You will see bubbles arriving in the header tank. On this engine it will be scrap due to cost unless you can repair yourself.

Cracks in the cylinder head will only occur if there has been a previous overheating event.

Failure of the filter heat exchanger only allows a small but steady introduction of oil to the cooling system but over a few days results in the brown oil in the header tank.

If the exchanger is replaced then the cooling system should be flushed several times with some radiator cleaning fluid.

Good luck with it.

Radox   
Fri Feb 19 2021, 08:06am
Joined: Aug 27 2019
Member No: #4044
Location: Bad Bergzabern
Thanks for the replies, I did not see all of them and posted in the linked topic. THe mods might delete that comment, I will post it here:

"Hi, I now have the exact same problem (oil in the coolant, but NO coolant in the oil, no overheating, car running normally) and I hope is the heat exchanger here too, and not the head gasket.

HOWEVER, the difference is, that my coolant sometimes overflows from the radiator cap and there are droplets all over the place.

I will finally be able to take the car to a Citroen dealer next week, but what do you thinki might be causing the overflowing?"

So, It seems pretty strange. We will see what the guys at Citroen will tell me.
jamescarruthers   
Fri Feb 19 2021, 08:17am
Joined: Jan 19 2014
Member No: #1548
Location: Cambridge
If they are anything like I’d expect a Citroen dealer in the UK to be I’d say you won’t be any further forward with your problem but your wallet will be lighter!

Cisco   
Fri Feb 19 2021, 10:06am
Joined: Sep 10 2013
Member No: #1429
Location: Glasgow
Hi Radox,

I agree with James that you may not get much help from a Citroen dealer. Most of them would hide under the counter if you arrive with a C6 . A private garage with a mechanic you trust might be a better bet for this type of car.

I do not know what is causing your coolant to overflow "sometimes" but what I can say is that if you have a headgasket which has failed or is failing then the problems will only get worse.

In my case that was my initial worry as I outlined in the referenced post. With the C6, headgasket problems are more common simply because of the thermostat and inlet plastic housings failing at around 100K miles causing complete loss of coolant (with no warning to the driver) and subsequent overheating/seizure.

If this has not happened to your car then you should be ok. My fingers are crossed for you.

Frank
Radox   
Fri Feb 19 2021, 10:16am
Joined: Aug 27 2019
Member No: #4044
Location: Bad Bergzabern
Cisco, I have changed the thermostat plastic housing (1336Y3) when I bought the car 2 years ago. What are you referring to with "inlet plastic housing"? Is this part 1336Y2 (which I also changed) or something else?

And I have had no overheating according to the dashboard meters since I bought the car. Hope the previous owner also hasn't had one.
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