Coolant help and WaterWetter notice
 

Now that summer is here, I want to change the H2O to coolant ratio in my 420SEL and in my daughter's 300TE to a 55/45 or even 60/40 H2O/coolant ratio.

I bought one of those nifty Prestone coolant gauges and tried to use it but alas! the markings in the guage only have boiling point readings and not ratios. :confused: The only "clue" they offer is that a 50/50 ratio offers boiling protection up to 129 degrees C. That figure is good for a 15 PSI radiator cap (about 103 in metric, but Mercedes uses a 140 cap).

I suppose that I could try to extrapolate forward or backward from that point (taking into consideration the different cap pressure). But not being mathematically gifted (that's why I am a lawyer, I can only count the really big numbers :D ) I was wondering if there is an easier way to convert boiling point markings into water/coolant ratios? does anyone have a handy-dandy chart available? Or is there a gauge out there that already comes with ratio markings?

Thanks;)

For you WaterWetter fans out there, Pep Boys is running a sale on this fine product. (I personally would NEVER set foot inside a Pep Boys store :cool: "Someone" who doesn't mind being seen inisde a PB store told me about the sale :eek: ). The sale price is $4.88 per bottle. It usually goes for about a $1.50 higher. Time to stock up!

Have fun.

Hopefully you'll be able to drain the heater core as well; othwerwise, your ratios will not be as expected.

Prestone AF1420P AF tester
 

Here's the pic from my page showing the markings on the Prestone model.

http://pages.prodigy.net/jforgione/AF_tstr.jpg

The complete thread: http://pages.prodigy.net/jforgione/MB_WW.html

Many thanks...
 

JimF and Tkamiya...many thanks for the posting pics of the calibrated gauge fro this math-challenged lawyer to use. :D

OK, another question for you guys. What is the best way to achieve the desire ratios? Drain coolant from the reservoir and refill with water? Drain teh entire system and start from scratch?

I guess I'd like to know the easiest and also most accurate way of doing this (short of taking it to my mechanic and having him do it, even for a lawyer I still like to do some DIY stuff). :D

Many thanks....

Do these testers work for MB anti-freeze?? I notice that they all state they are for tesing "ETHYLENE GLYCOL" type antifreeze blends.

I don't think the genuine MB stuff is EG based - as I recall its base is something called "GLUCOSTANE" or something like that.

I tried to use the Prestone tester on some MB antifreeze that I'm sure was mixed 50/50. The tester identified the mixture as 70% antifreeze/ 30% water.....

Tim

Either way works!
 

I 'tweak' my mixture by removing some from the overflow reservoir (OR). So if mixture is close, it works great.

On my car, the OR holds a little over one gallon, which is apx 25%of the total. So you can get to 40/60 (af/water) ratio very easily.

Yes, Prestone checker works great with EG since that's the main ingredient in MB af.

I always start from a completely drained system. I also keep an empty antifreeze jug stashed for mixing purposes. I pour in about 40-45% AF and top off with water, then pour that mix into the system after checking the ratio with the tester. Continue the extra jug mix method until the system is full, then add a bottle of Redline's Water Wetter.

Thank you guys!
 

Thank you for all your tips. I will work this weekend on adjusting the mix on both my 420SEL and my daughter's 300TE. Now that it is getting warm here in so. California, this is a good time to do this procedure. :cool:

Tkamiya, I found out the "hard" way about the in-fender resorvoir. While replacing the external overflow tank in my daughter's wagon I also decided to replace the top, overflow hose (it was old and ratty looking) hose. I had assumed (silly me) :rolleyes: that it was just a hose going into the fenderwell to drain to the outside. Hah! After looking around I decided to remove the fender...no, not the fender :D just the fender lining...I discovered the real overflow tank...:p

Well, I replaced the hose and everything is now nice and new...so all I have left to do is to change the coolant/water ratio

Again, thanks for all your help....