Brown Coolant

[dragonhorse]

Hi, i've just purchased a 1995 E280 with a full service history (last service in march),and new MOT. From the point of collection to home was 150 miles. At around 50 miles in i noticed the coolant level indicator coming on, very dimly at first but gradually getting brighter.i pulled in and even though it was getting dark the level in the expansion tank seemed fine. The next day i started it up and hey presto no light! I had another look at the coolant and was concerned to see the coolant was brown and with the look of syrup.Looking through the work done a new radiator was fitted last march same time as the last service, and a complete new exhaust system and catalyst fitted a year ago.
can anyone tell me what problem i have here? do i have to drain the coolant or is it something more serious? Apologies for long first post!

 

[television]

Hello and welcome,, sad to say that this could be a head gasket problem,,have a look at the dip stick (oil) for any water bubbles and on the inside of the oil cap.

The oil may be getting into the water and not the other way around,, drain the water out and refill, then run the engine to operating temp and see if any oil gets into the water

 

[dragonhorse]

I forgot to mention, i checked the dipstick and the oil filler cap and they looked fine no water bubbles.

 

[DougCLK320]

The head gasket on my E280 (1995) failed and displayed exactly the same symptoms as yours. Had it replaced by an independent who told me that 100k miles was the normal life of these motor's first head gaskets. These gaskets were modified / improved and the replacement can be expected to last the (remaining) life of the engine. Once replaced, make sure you thoroughly flush out the cooling system as oil will damage hoses etc.
Sorry to not have more positive news for you....
Doug

 

[BlackC55]

Sounds like a headgasket to me.

 

[DougCLK320]

The common failure of these gaskets is between oil and water cut-outs. The car will continue to drive unaffected as full compression is maintained and, thanks to the engine’s oil pressure being considerably higher than that in the cooling system, oil will leak into the water and not the other way round. Still needs doing urgently as all that oil in the water will be damaging all the rubber based cooling hardware.
I, unfortunately, had to have the head skimmed – adding to the bill, but afterwards it ran better than it ever had before – and felt quicker.
Doug

 

[wireman]

If it is head gasket failiure it is cylinder to water in your case.

The exhaust gasses cause the coolant additives to solidify and look like disolved rust that feels greasy (the antifreeze and corrosion inhibitors properties will be destroyed).

MB recomend the coolant be changed at 2 year intervals on my 124, so if yours is that old change it.

It will be helpfull to flush out the entire cooling system with a real chemical flushing kit ie Radflush, just rinsing it will not remove the sludge from the degraded coolant and this sludge will collect in such places as the heater matrix and radiator where low flow rates won't carry the stuff away, the end result will be poor cooling system performance or a heater which doesn't and big bills to get them working again.

 

[dragonhorse]

Just got the merc back from the garage and i've never breathed such a huge sigh of relief. The headgasket is fine, the problem was the garage that fitted the new radiator at the last service never flushed the system!
So a new radiator has been fitted and the job has been properly done all at a fraction of a huge bill i was expecting to pay.
The coolant sensor was faulty so a new one is on order

 

[television]

Thanks for posting back with a good result