Black Deposit in coolant reservoir

[afnan]

Hi,
Creating a new thread for clean post with history.
2012 GC 3.0 CRD EXF

History of works done

1. New water pump and Metal pipe that runs from valley to oil cooler
2. New oil Cooler
3. New rubber hoses on the back side of engine
4. New Alternator
5. coolant flush recently
6. New Thermostat

Some Test Info

1. Coolant Pressure Test shows NO leaks and No coolant loss
2. the coolant is clear
3. No blow back in the coolant reservoir
4. no white sludge on the reservoir Cap or engine cap
5. min running tempafter warmup 93 and Max 97

I recently got Oil cooler replaced and cleaned the system (10-9021). Cleaned the coolant reservoir as well.

Took the car and covered 200 km today. I can see the black soot kind of deposits building on top of the tank. The coolant is absolutely clean.

No driveability problems. I was thinking perhaps I opened the EGR valve motor (not the entire cooler) and there is a gasket they might let soot go to the coolant but if the coolant pressure test pases I am not sure about that.

At this point I don't have clue where this black soot is coming from. No symptoms pointing to head gasket.

[drover]

Would not get soot from a head gasket...............

Coolant would flow into the EGR system and then into the manifold and level would drop, poor starting first up and other problems in time.

My first thought is just residue left in the system, if oil has leaked into the cooling system there will always be residue left no matter how many times its flushed, it will weep out of the hoses........................
The other thing is if its only a few bits floating around I would say bits of soot crud got in when you fiddled with the EGR, the hard baked stuff, even with flushing not everything will get out, too many places for things to get lodged especially if the thermo is left in place and even with the heater on stuff will get held...

See if you can collect a sample on strip of cloth or similar or maybe onto a strip of plastic, something that will catch the black stuff so you can see what its texture is....

You can get coolant filters which fit inline to collect crud, that may be a solution to cleaning ... I know I had them on my trucks just not sure about cars.

[afnan]

Decided to give cleaning the reservoir a go. Removed it, tried everything brake cleaner, bleach, soap and scum remover, degreaser, detergent, CLR, basically any chemical in household to clean it but that deposit didn't budge. Ended up moulding an old tooth brush to clean two columns.

The bucket in which the coolant was collected got some sticky deposits and only degreaser cleaned it. No wonder why you can't clean the cooling system after oil mixup.

My basic idea is to see how much time does it take for the black stuff to come back


Question is if gasket that goes between my EGR valve and EGR cooler is compromised and soot enters from there, I should have coolant loss which i don't seem to have.

Originally Posted by drover

Would not get soot from a head gasket...............

Coolant would flow into the EGR system and then into the manifold and level would drop, poor starting first up and other problems in time.

My first thought is just residue left in the system, if oil has leaked into the cooling system there will always be residue left no matter how many times its flushed, it will weep out of the hoses........................
The other thing is if its only a few bits floating around I would say bits of soot crud got in when you fiddled with the EGR, the hard baked stuff, even with flushing not everything will get out, too many places for things to get lodged especially if the thermo is left in place and even with the heater on stuff will get held...

See if you can collect a sample on strip of cloth or similar or maybe onto a strip of plastic, something that will catch the black stuff so you can see what its texture is....

You can get coolant filters which fit inline to collect crud, that may be a solution to cleaning ... I know I had them on my trucks just not sure about cars.

[OLMATE]

Originally Posted by afnan

Decided to give cleaning the reservoir a go. Removed it, tried everything brake cleaner, bleach, soap and scum remover, degreaser, detergent, CLR, basically any chemical in household to clean it but that deposit didn't budge.

This is what I done to clean mine like new!!


Went to Bunnings, bought a packet of GLITZ Calcium removal TABLETS,
pop one in,
add hot water,
a good squirt of JIFF or some other creme cleanser,
( sounds like a bloody recipe )
Half fill with Hot Water,
NOW for the gear to actually get in there and break all that hard scaly shit down from the inside, COUNT out 10 small m6 NUTS, make sure you count how many go in and make certain the same amount comes out, Old radiator cap on, and after 10-15 minutes of walking around shaking the shit out of it, youll have a nice clean and actually clear plastic new looking reservoir again, if its bloody filthy it might need a second go,
The nuts worked a treat in breaking down the baked on scale, they are small enough to actually work their way around to all the chambers inside the bottle, Whilst shaking the bottle around you can actually see all the baked on shit disappearing

Bottle is easy to remove as you found out, 2 x 10mm bolts, couple of hoses.



Note**
This is what worked a treat for me and I am in no way suggesting others follow suit

[afnan]

Why the heck I didnt think of that nuts thing. I have been trying to insert a bottle cleaner but of no use. Yes, will do that next time. I think this grime cannot be removed from radiator tubes or the remaining system. I think I got to live with it and make sure Soot is not entering the system.

Originally Posted by OLMATE

This is what I done to clean mine like new!!


Went to Bunnings, bought a packet of GLITZ Calcium removal TABLETS,
pop one in,
add hot water,
a good squirt of JIFF or some other creme cleanser,
( sounds like a bloody recipe )
Half fill with Hot Water,
NOW for the gear to actually get in there and break all that hard scaly shit down from the inside, COUNT out 10 small m6 NUTS, make sure you count how many go in and make certain the same amount comes out, Old radiator cap on, and after 10-15 minutes of walking around shaking the shit out of it, youll have a nice clean and actually clear plastic new looking reservoir again, if its bloody filthy it might need a second go,
The nuts worked a treat in breaking down the baked on scale, they are small enough to actually work their way around to all the chambers inside the bottle, Whilst shaking the bottle around you can actually see all the baked on shit disappearing

Bottle is easy to remove as you found out, 2 x 10mm bolts, couple of hoses.



Note**
This is what worked a treat for me and I am in no way suggesting others follow suit

[drover]

Actually looks good in the photo's, it will go in time......... my theory is No leaks, Temps are good its working fine leave things alone..............

[afnan]

Originally Posted by drover

Actually looks good in the photo's, it will go in time......... my theory is No leaks, Temps are good its working fine leave things alone..............

BTW what is your avg running temp and transmission temps?