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Cooling System Flush - E420

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davegt's picture
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The oil change on our "new to us" 1995 E420 went fine once I got the topsider oil extraction device to work. 8 minutes...sure...more like an hour but it got all 8 qts. out. Guess I need to find someone to remove the rounded off drain plug that has never been off the oil pan.

Next up is the cooling system flush. Now that the encapsulation panel is off, I will attempt to drain the system. The radiator drain seems simple enough but have no idea where the engine block drains are or what they look like. Some pictures would help.:frown:

So, once I drain the system with some kind of pans and figure out where to recyle it...what's next? Should I just replace the hoses (how many?) and refill or is there a burping process to learn?:confused:

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Re: Cooling System Flush - E420

An alternative to consider is this: Simply drain out what you can using the lower radiator hose. Refill with clean water. Run the engine to get it hot, let it cool, repeat the lower hose drain. One or two of these kinds of drainings, you'll have removed most if not all of the existing coolant.

Install pure coolant in the amount specified (probably 4-5 quarts) for a 50-50 mix, and top off with water.

Done.

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George Murphy's picture
Oak Ridge, TN
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Re: Cooling System Flush - E420

Refer to the MB Maintenance Manual for drain locations.

Here's how I did my 1989 300E:

Remove the engine thermostat and hose; disconnect the heater return at the left rear of the head; disconnect the heater supply to the aux water pump; check open the block and radiator drains; remove the coolant reservoir cap. Flush the heater core from the RETURN end at the left aside of the head back through the supply.

Use a garden hose and feed water into every opening possible in both directiond until clear water comes out of other open "holes".

Be sure to flush coolant reservoir and over flow bottle located behind right front fender liner - remove liner to get to it.

When all clear water has drained out, re-attach hoses but leave thermostat off.

Pour in ONE HALF system capacity MB brand antifreeze into block and reservoir - DO NOT USE THE CHEAP GREEN STUFF! It can erode alloy engine parts. and embrittle plastic coolant system components.

i.e: If capacity is 12 quarts, pour in six quarts of MB brand antifreeze. Then button up the system and add remaining amount clear water into the coolant reservoir - make sure overflow bottle in the RF fender is empty.

Start the engine with DEF button pushed to assure coolant is circulated through the heater. Shut off after fully warmed up and add any needed water to the coolant reservoir "Kaltwasser" mark.

Re check next morning that level is correct.

The following is quoted from the Mercedes-Benz Service Microfiche System,
Dated 04/93:

"Use water which is clean and not too hard. Drinking water frequently, but
not always, satisfies requirements. The content of dissolved substances in
the water may be of significance for the occurrence of corrosion. If the
water quality is not known, DISTILLED or fully desalinated water should be
used. For water quality see Mercedes-Benz Specifications for Service
Products."

From Mercedes-Benz Specifications for Service Products, Section 310:

Fresh water quality with a coolant composition according to item
(engines for passenger cars and commercial vehicles)

Sum of alkaline earth (water hardness): 0 to 3.6 mmol/l
(0 to 20 degrees d)
pH value at 20 degrees C: 6.5 to 8.5
Content of chlorine ions: max. 100 mg/l
Total content of chlorides + sulphates: max. 200 mg/l

*Conventional designations for water hardness in various countries:
1 mmol/l = 5.6 degrees d = 10 degrees f = 7.02 degrees e = 100 mg/kg CaCo3 US

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Regards,

George Murphy

MBCA Technical Director

865-482-9175

1999 C43 AMG

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Re: Cooling System Flush - E420

MB manual? Well, if I had one, I most certainly would. But, I don't, that is why I am asking for a bit more detail or photo of where they are....

The instructions are very detailed and appreciated!:Thumbs up:
Only thing is, it seems to be an easy thing to do in the yard if I didn't care about spilling antifreeze into the environment, but how do I do this in the garage without spilling fluids everywhere!??! And where the heck do you take the antifreeze to be recycled?

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Re: Cooling System Flush - E420

FWIW, down here I run 30/70 + a bottle of Water Wetter..:)

Less coolant = greater cooling capacity.

Jonathan

----------------
Now playing: Dave Matthews Band - Don't Drink the Water
via FoxyTunes

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Jonathan Hodgman Blue Ridge MB
http://www.blueridgemb.com
Offering Enthusiast Service, Restoration and Tuning.
(404)805-1357
2005 E55 Estate 2003 CL500, 93 500E Euro, 93 500E Brumos, 91 560SEC ECE, 91 500SL Euro,  87 AMG Hammer Wagon & Sedan 86 560SEL AMG 6.0L 32V,

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Re: Cooling System Flush - E420

Hey, Jono...

How about just doing what Don mentioned with the lower radiator hose a couple of times? Seems to be a bit easier in my garage with less spilling...

Also, should I just change out the thermostat as a matter of course?:confused:

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