Changed coolant, runs hotter! - PeachParts Mercedes-Benz Forum

edge · #1 04-30-2003, 07:44 PM

So I changed my coolant with 55% MB coolant/45% distilled water and the engine which use to run 88 or so now runs 100 degrees. No leaks, what's up with this?

kerry · #2 04-30-2003, 07:55 PM

air bubble?

edge · #3 04-30-2003, 08:02 PM

How do I get it out, or will it just surface with time?

gsxr · #4 04-30-2003, 08:02 PM

Pretty likely you need to burp the system, if you made NO other changes other than the liquid. 88C is more normal for a good, clean system.

engatwork · #5 04-30-2003, 08:12 PM

The way I burp em is to disconnect the upper radiator hose and hold it down low, pour coolant mix in it and then move it straight up. The level will fall in the open hose. I continue to do this until it no longer goes down when I move it up.

kerry · #6 04-30-2003, 08:15 PM

Run the heater full blast and open up the bleed bolt on the top of the thermostat housing while you run the engine. The system is poorly designed for getting rid of air bubbles.
Some people fill their systems through the top radiator hose while the car is parked on a steep hill (ramps?).

edge · #7 04-30-2003, 08:22 PM

Thnaks, guys...I will try all that tommorrow afternoon.

Mick J · #8 05-02-2003, 02:13 PM

That's a high concentration of coolant which reduces the heat dissipating properties of the solution. I'm not saying it's too strong, maybe it was weaker before and cooled better.

edge · #9 05-02-2003, 02:57 PM

Thanks, Mick, I think you're right. There's no air in the upper radiator hose. I have to let som e out and add water. I bought some Water Wetter, supposedly that helps it lowere the temp.

ck42 · #10 05-02-2003, 07:25 PM

After I'd changed the coolant when my water pump failed, everything seemed to be fine except the GURGLING in the heater core in the dash.

Well....apparently, that air bubble in the heater core decided to move on one day. I suddenly started seeing higher temps (10-15C higher).

I checked the coolant level and noticed it was low. So, I added some water and topped it off. Drove some more...still running warmer than normal. Noticed the coolant level was low again....topped it off AGAIN.

This went on for about a week! After all was said and done, I had added 1.5 GALLONS of coolant to the system!

But, the temperature is now back to normal and no more waterfall sounds coming from the dash

So...I can certainly testify to the air bubble 'issues' in these engines.

Next time, I'll try the slanted, rad. hose fill method and see if that helps.

JohnM · #11 05-02-2003, 10:37 PM

My factory MB thermostat ran ~5 to 10 deg hot for about 6 months before it “broke in” and went back to 85 degrees, now it seldom moves from there. I also had a bit of an air pocket that formed. I have a sloped driveway and used that to burp it.

Maxwell · #12 05-03-2003, 01:06 PM

I wouldn't use distilled water, My Auto Shop teacher was saying it can leach minerals out of your block, increasing corrosion or something, if you're tap water is bad i'd use bottled drinking water. As for the high heat i'd agree it's probably an air bubble

gsxr · #13 05-03-2003, 01:24 PM

Distilled water is fine, but ONLY if it is buffered with anti-freeze, or a product like RedLine Water Wetter. Older Mercedes documentation specified distilled water, now they say "tap water with low mineral content", meaning not hard water. Bottled water is probably better than hard tap water but distilled would be preferred, as it is pure with zero minerals.

Using 100% distilled water is BAD and please don't do that! Even using 100% tap water is bad if you leave it in the engine for more than a few days or weeks, I did that once and had massive rust come out when I flushed it a couple months later. The anti-freeze (or Water Wetter) acts as a corrosion inhibitor, lubricant, and a chemical buffer that prevents the water from pulling the metals out of the block & radiator.

edge · #14 05-03-2003, 07:48 PM

Thank you all for your insights. I let out a gallon out, added water and Water Wetter and will watch the overflow over the next few weeks.

coachgeo · #15 05-03-2003, 08:20 PM

for testing purposes you should not have added the water wetter. We wanted you find the problem; not fix the symptoms. That way the rest of us don't Fawk it up when its our turn hehehehe. :p :p

For the sake if testing a hypothosis of why it was getting hotter the way to go woulda beeen somedin like this.

. First see of the burping and heat on Hi for a few weeks to finish burp changes things

. then change % of coolant

Course then again if all you want to do is drop your temps back down........ you do what u just did

hope it works out well.