I did a quick search for info about testing MB coolant for effectiveness but didn't come up with anything. I have '97 E320 that had its cooling system flushed and refilled with the proper solution of MB coolant about 30 months ago. This morning when car was at dealer for some suspension work, the tech did the usual "courtesy inspection" and announced that my coolant had no freezing protection. Car runs great and temp never goes above about 90 degrees on the guage regardles of outside temp, use of A/c or length of time engine has been run. I want to test the contents of the radiator myself but all that I have is Prestone bulb-type tester that is several years old. Will this tester give a reasonably accurate indication of the properties of the MB coolant solution?

TIA

Yes.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I used the tester on my coolant and got a reading of - 40+ degrees. I was sure I had good coolant in the car.

okc,

I have seen information on OAT and HOAT coolants that says the pH must be tested to determine condition of the coolant and the old style testers don't provide enough info. I don't remember if this applies to freeze protection. You might want to Google search automotive coolant to decide if you need to check any farther. I don't think a technician just saying coolant won't provide freeze protection tells much of the story anymore. Corrosion seems to be the problem with modern engines and will be a cause for worry first.

My wife has a PT Cruiser and I haven't been able to find any specific information on what the pH should be before the coolant needs to be changed . If you find any good directions , or if anyone else has a reliable source ; I would like to know also.

dang

Well, the bulb tester just measures liquid density and all it tells you is the freezing and boiling points of the solution or how much antifreeze you have in relation to water. It tells you nothing about corrosion protection. So use it to verify your water/antifreeze mix is right, but nothing else.

I don't understand. Is that -40 or +40? Fahrenheit I assume?

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

It 40 C/F , +/- ...............

Actually , if it is -40, it does not make any difference if it is C or F .....
...........ya know what I mean ???????

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A Dalton

Testing aside, Mercedes has a 3 year replacement interval on coolant, regardless on mileage.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

To me it is pretty unbelieveable that the coolant has lost it's freezing protection after 30 months. I don't buy it.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

The only way it would do that is if it was diluted with water.

IIRC on the Zerex G05 bottle it says 5 years / 150K miles.

Yes I know -40 is about the same both in C and F. If he meant 40F that's actually impossible since that's above the freezing point of water. -40F on the other hand, should be sufficient and if I recall correctly that's about 50/50 water/ethylene glycol mix.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I think the newer coolant (blue in color) used in 2003 has the 5 year replacement interval.

The yellow-ish coolant used in W124 / W210 / W202 / W140, etc. chassis has a 3 year replacement interval.

What's on the Zerex bottle is also independent of what Mercedes requires.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

>

Close , but No Cigar ..

Minus 40 is not About the same , they are Exactly the same..
..and 50/50 H20/EG mix is -34F.

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A Dalton

I meant that the tester showed something like -43 degrees as the freeze point.

According to my local shop the PH of HOAT should be 9.8 to 10.5 to provide the correct level of corrosion protetion on an aluminum head engine.

MB coolant has a neurtal ph.

I know this coolant thing is about as hotly debated as synthetic vs. dino oil, but Stu Ritter in the Star Magazine writes that MB coolant should only be used in Mercedes engines.

MB coolant also has conditioners in it that keep the seals in your water pump and the hoses in your car healthy.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Made by Zerex for MB. Same stuff is sold under their name.
My local MB shop uses Zerex with no problems at all.