Grey residue in coolant/expansion tank.

[Tikka]

Hi.
I have a Jeep with OM642 Mercedes Diesel engine.

I have recently noticed a light grey coloured residue in my plastic expansion tank. You can see it on the front of the tank. Anyone any ideas what this may be?

The coolant itself is very clear with just the blue tinge of the antifreeze. Coolant is 18 months old and is Mercedes MB325.0/G48.

Any thoughts?

Thanks.

 

[xgmad]

The grey stuff could be sillica , did you do a flush?

 

[Tikka]

Hi xgmad.
Thanks for helping.

The coolant was changed out by the garage when i had a leaking radiator replaced. They were asked to flush and replace the coolant so i can only trust they did the flush. They definately replaced the coolant as the old stuff was orange. They are a Mercedes specialist hence they used the Merc G48 stuff.

 

[JHZR2]

Grey is strange. Is there an oil to water cooler?

 

[Tikka]

Grey is strange. Is there an oil to water cooler?

Hi.
Thanks for helping.

Not on this engine no. The tranny has a seperate radiator.

Not loosing coolant. There is no 'mayo' on the oil filler cap and the actual coolant is clear and no residue on the coolant tank cap. It is strange indeed. I cant really think what it may be.

 

[kschachn]

To add to what JHZR2 posted, the times I've seen gray stuff inside the recovery tank it was oil.

 

[Tikka]

To add to what JHZR2 posted, the times I've seen gray stuff inside the recovery tank it was oil.

Hi.
I am as sure as a layman can be, that it is not oil. I had oil contamination problems with an old K series engine in a Freelander and it did not look like this. As i said, the coolant is very clear. I would have expected any oil to have emulsified in hot coolant. Would you agree?

Could the fitting of the new radiator have possibly caused this in some way?

I may just remove the Tank and give it a good clean out and see what happens. A bit of a head scratcher is this one.

 

[xgmad]

Hi xgmad.
Thanks for helping.

The coolant was changed out by the garage when i had a leaking radiator replaced. They were asked to flush and replace the coolant so i can only trust they did the flush. They definately replaced the coolant as the old stuff was orange. They are a Mercedes specialist hence they used the Merc G48 stuff.

To keep it economically friendly, I would take the grey stuff out of the reservoir and replace it with more G48, and see if it comes back.