Possible oil in coolant? : C220 petrol

[norfolkngood]

Evening all.

My first post & request for help on here.

I own a 1995 C220 petrol. Car has been reliable over the 25,000 miles I've done (milage is a genuine 93,000 from new) but over the last few weeks I've noticed a slight loss of coolant. Nothing serious, and no warning lights.

Topping up the rad today, I noticed what looks like emulsified oil under the rad cap. I used a bit of glass tube to extract some coolant from the rad; l can't see any oil in the coolant. Dipped the oil, the oil on the dipstick is "clean" with no sign of water. Same under the oil cap, no sign of the "mayo" gunk which could indicate head gasket problems.

Anyone got any ideas please, or am I being a bit paranoid?

Cheers

 

[grober]

Take out the spark plugs and have a look at them. If any one of them have a "damp look" blackish colour deposit compared to the others as if the plug was oiled and a wet look to the top of the piston [ but the deposit isn't oil as such ] then thats the cylinder that's possibly gone. A very hard top hose [pressurised] when the thermostat has opened is also an indication. If these tests are positive then lots of garages use their exhaust gas analyser probe to check the coolant headspace for traces of combustion gases--its a very sensitive test. If you do get the CHG renewed make sure the head is trued/skimmed if its warped and use new CH bolts since CH bolts of that engine vintage can stretch.

 

[Smiley]

loss of coolant could be a number of things other than the HG - small leak on the rad, water pump starting to fail. Get a pressure test done - or sniff test the coolant for exhaust gases. |

 

[lynall]

Has this engine got an oil cooler linked to the coolant system?.

Oil in the coolant can only come from a few places top of list is head gasket 2nd is the oil cooler if fitted.

If its very slight oil contamination i would say hg if heavy oil mess got to be cooler again if fitted.

Ps good way to clean cooling system afterwards is to put in half a cupful of tfr or ctfr fill with water go for a drive, drain and refill with plain water go for another drive then drain again and refill with correct coolant.

Pps let it cool in between changes!


Lynall

 

[unitfreebie]

Does your Tranny have a cooler in the radiator??? If so, make sure the coolant is not getting into the Tranny (722.6 5-speed) as it will dilute the Tranny fluid and wear the Clutch spindle Brass Bushing causing complete failure! Do a search on the W210 forum of Benzworld.org for Radiator Transmission leakage. Good luck...

 

[grober]

Smiley and unitfreebie make good points about alternative causes of fluid loss/mixing . MB offer a very sensitive test for glycol (coolant) in the auto-transmission fluid to rule out failure of the heat exchanger in the radiator. If your car is a manual you can ignore this possibility of course.

 

[norfolkngood]

Thanks for all of the above. I'm going to ask the local independent (Auto Technic) to have a look for me.