Hi,

I was told by local MB mechs in my country (the Philippines) that using 50/50 MB coolant/water mix corrodes the water (coolant) channels in the head - making them larger and thus requiring a trip to the welding shop where it will be "resized" back to normal. For this reason, the local mechs are saying that it's better to use water than coolant.

Is this true? Has anyone actually needed a water channel repair in the head/block due to corrosion? They're quite positive it is not the well-known headgasket problem.

I'm guessing that the local mechs use regular tap water (very hard water here) when creating the 50/50 mix. I for one am leaning towards using distilled water and Redline's Water Wetter (ph8.6) only.

Any thoughts on this possible "urban benz legend"?

Thanks

Total BS. Use the MB recommends for your car.

Duke

This is worse than BS.

One reason for using coolant is to prevent corrosion. Pure water, irregardless of whether it's hard or soft will corrode much faster than a 50/50 mix of coolant and water.

The MB techs that told you this were either yanking your chain or are in the wrong line of work.

Find another shop

Ford has paid me good money to examine head cooling passages from cars that had peculiar conditions during warranty. A few of the heads investigated were abused by people who drained the factory coolant and used straight water, typically truck owners in Texas who want to increase thermal transfer without realizing the downside of such action. The nucleant boiling from using straight water cavitated (pounded holes) the inside water passages until it reached the outside of the head, resulting in a leak and total loss of coolant.

A 50-50 mix (and proper 15 psi pressure) will raise the boiling point to where you don't get this phenomenon. Whoever told you the story got it backwards. The heads for repair he mentioned were the result of using straight water, not the reason for using straight water.

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95 E320 Cabriolet, 169K

Truck owners in Texas? Not following the rules? Would that really happen???

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'97 E320 Black Opal
'86 300E Smoke Silver / Burgundy (retired at 198K)
'63 Austin Healey 3000 Mk II (BJ7) (reluctantly retired)

not to mention water is not as effective a lubricant for the water pump as coolant.

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David
1986 300E Anthracite + ECodes + MB Mileage Award

Why would anyone run their car on water alone? That sucka would overheat!! While performing a coolant flush on my 500SEL, I put water in the system and within a few minutes the car would start to overheat -- had to use the heater to keep the temperature down. Then when I opened up the coolant reservoir, the water burst out with high pressure.

To each their own...

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver