X03

the benz has been overheating and I think its because the water ratio is too high. Can I just pour in coolant or 50/50 mix and see if it helps level things out? Or do I need to flush and ensure a proper mix from the start?

ptoro01

Try a new fan clutch, water ratios won't give a drastic change. The cap holding pressure is crucial tho.
You can get a water mixture tester for a couple bucks so you can set the mix to spec.

neanderthal

You need to figure out what the actual problem is.

Running a high water mix should NOT cause overheating as water has better heat dissipation properties than antifreeze/ coolant. I ran my 1990 300E 2.6 on mostly water as it never gets freezing here in LA. I watch my gauges like a hawk though, always have, always will. I have caught the temperature creeping up and been pulled over to the side of the freeway before it got to the red.

I suggest you start by checking/ changing your thermostat. Check the condition of your fans. Check you belt. Check your temperature sensor. And keep going. Start with the items that are free (check X) then move on to the cheapest items.

Isolate the problem.

X03

haha no easy way out huh.. the old radiator cracked so we replaced that and the hoses. I find it weird that the thermostat is the problem since it was working fine before we replaced everything. now I cant drive for a mile or a few minutes before it gets close to the red and I have to pull over and blow the heater.

Is there a way to check for blockages or see if it's circulating properly?

Other things to note: the fans dont turn on at all. the belts look ok. the cap for the resevoir is tight. the temp sensor is good.

neanderthal

I didn't say the thermostat is the problem. I said check that because all you have to do is stick it in a pot of water and boil it to see what temperature it opens. If it opens, you know it's working, and it's cost you nothing but time.

If you have been running a water only (or a high percentage of water) then there is a chance that you've got calcification or other build up in the coolant passages as a result of not having the right pH balance. Anti freeze alone won't cure that, you'll have to flush your system. Mercedes has a citric based coolant flush available at the dealer. Parts stores sell their own cooling system flush but the prevailing wisdom is that the Mercedes one is best.

Overheating is a very common topic. Use the search function. All the information you want is out there on the various Mercedes fora. My advice is to utilise that information to isolate your problem and solve the problem. Do you want to replace the entire cooling system because you didn't do the "newspaper check" on your fan? A test which, if negative (failed test) can be resolved with a $3 tube of silicon at a hardware store.

We can't diagnose it for you, given the paucity of information you have given us. But what you seek is out there. If your fans don't come on that's a good place to start.

ptoro01

Shot in the dark but head gasket..

Based on....t-stats like to fail open, broken water pumps leak but still pump, and without any fans but just the airflow at 30+mph, you'd get a lot further... And the old rad spilled its guts and thus spiked the temperature well into the red..

Unless the temp gauge is full of it.....

kluvsbenz

:::Bump:::
Replaced fan clutch, water pump, radiator, t stat and it creeps above 100 when stuck in traffic, idling. ac off or on. What gives? When driving in traffic, i goes back down to 87.

BENZITCH

It is working correct.
It will go to a 100 sitting, the fans come on keeping the temp there until you start to move and the viscious fan engages and the fans(electric and viscious) bringing the temperature back down.