coolant change and flush - PeachParts Mercedes-Benz Forum

adiaw83 · #1 06-24-2003, 02:14 PM

Is it ok to change and flush the coolant while it is all warm. I've been on the highway for a little while so everythings probably warm and the pressure's probably up. Should I let everything cool down first? the car is an 83 300sd does anyone know the capacity? alos am i supposed to do 50 50 coolant water ands what shold i pour in first? thanks

#2 06-24-2003, 02:37 PM

You really shouldn't do it when the car is hot. You don't want to run cold or even cool water into a radiator and block that are 80 degrees Celcius or more. Let it cool down a bit first. You could crack something. As far as the capacity is concerned, it should take about a gallon and a half of coolant and a gallon and a half of water, if I remember correctly.

gsxr · #3 06-24-2003, 04:03 PM

Make sure you ONLY use either Mercedes anti-freeze, or the new Zerex G-05 formula. Everything else is BAD (well, except maybe Evans NPG but that's expensive). Seriously, don't cheap out on the a/f. If you don't expect to get temps much below freezing, I'd just use one gallon of anti-freeze and fill the rest up with distilled water. I also add a bottle of Red Line Water Wetter. Now if you live in an area that has harsh winters, like North Dakota or upstate NY, you'll need the full 50/50 or 60/40 concentration for maximum freeze protection. But down in DC, 40/60 should be *plenty*, and avoids having 3 leftover quarts of A/F hanging around!

BTW, I agree with the hot/cold thing... drain & flush coolant cold, drain oil hot. If you must run the engine for a coolant flush (like the factory citric acid procedure), let it cool down to an indicated 50C on the dash gauge, then spray the outside of the engine with water (from your garden hose or whatever), before sticking the hose into the radiator & water neck etc... that will help prevent cracked heads and/or gaskets. BT, DT, once I put a cold hose into a warm engine and was rewarded with oil in the coolant...!

I learned my lesson. Don't repeat my mistake!

wagonboy · #4 06-24-2003, 06:59 PM

Perfect timing as my temps are starting to creep up.
What do you guys suggest as a flush? Prestone super flush or something else?
The Zerex G05 formula, easily found at local Kragen or WalMart?
TIA for any help.

wagonboy

gsxr · #5 06-24-2003, 07:03 PM

Prestone SuperFlush, or Super Radiator Cleaner, should be adequate. MB specifies a relatively complex citric acid flush. The Zerex stuff won't be at Wal-Mart because they only carry Prestone products. Kragen or AutoZone should have the G-05, or just buy it from your local MB dealer - should be about $12/gallon, which isn't bad once every 3 years...

wagonboy · #6 06-24-2003, 07:06 PM

Thanks for the assist gsxr. I got my job for this weekend. Plus the tranny fluid and filter change, plus the left rear power window not opening, plus the hi mileage badge that I still haven't installed coz my cousin lost the mounting parts, plus the oil pan filter change. Hehehehe, it just keeps piling up.

wagonboy

73MB280SEL · #7 06-24-2003, 09:24 PM

I just did mine and am very satisfied with it. I'd go ahead and change out the thermostat if you haven't recently.

You should drain as much old coolant out as you can, take out the thermostat, put the housing on, and flush out the rest of the bad coolant with water. You'll need to repeat the fill, run, drain exercise to get all the green stuff out. Make sure and turn on the heater. Then add the Prestone superflush and follow the directions.

I didn't get all the old coolant out when I put the Prestone flush in, so I think that the old coolant/gunk nullified the flush. I really think you need to take out the thermostat and flush the system with water to make sure and take full advantage of the flushing.

I'm going to have to redo mine to get all the oil out.

Once you run the flush for the prescribed run time (6 hours), you need to repeat the process of drain, fill with water, run, drain. Then fill with Zerex.

And, the Zerex coolant isn't that expensive and I got it at Pep Boys.

Sholin

wagonboy · #8 06-24-2003, 09:26 PM

Thanks, on the thermostat, is it ok to use Stant or just stick with what Fastlane sells?

wagonboy

73MB280SEL · #9 06-24-2003, 09:55 PM

Funny thing is that I don't think thermostats are what they used to be. There has been alot of threads on relatively new thermostats dying prematurely.

I bought mine at the local european shop (Kerr Automotive), but I'd think the most important thing is to get a new one in there.

I also had concerns that the flush would damage the thermostat. It's got a wax pellet in it that melts at a certain temp (I think that is how they work). Maybe the flush detergent would dissolve it. I was also worried about oil contamination of the thermostat. My car blew a head gasket before I bought it. Although it has been fixed, the dumb mechanic didn't flush and de-oil the cooling system. I think the oil made a mess of the old thermostat.

I'm going to buy another thermo to keep in the car with me. I've just heard too many people talking about premature failure.

Sholin

73MB280SEL · #10 06-24-2003, 09:57 PM

While your at it, probably ought to unscrew the aux fan and see if there are bugs/dirt/dog hair trapped under there. I failed to do this and am going to this weekend. This makes a big difference to your cooling system.

ericnguyen · #11 06-24-2003, 10:03 PM

MB coolant or Valvoline Zerex G-05 is more or less compatible with either extended (5/150) dexcool coolants or conventional green coolant, so if you still have some green or dexcool in your car, it's still OK.

Anyway, it's always better to get much of the old crap out.

Eric

gsxr · #12 06-24-2003, 10:20 PM

Yes, tiny quantities of old coolant won't hurt anything. But you should be able to get out 99% of the old junk with no problems. Don't forget to fully flush out the heater core, and open the drain on the engine block too.

For the thermostat, I'd recommend an OE dealer t-stat (not aftermarket) from FastLane, BuyMBParts, or your local stealer. I've heard some odd stories about the aftermarket ones, and possibly even the supposedly "OEM" stuff. Definitely don't use a McParts unit if at all possible. Oh, the wax pellet is sealed, so various contamanints (sp?) won't damage it.

wagonboy · #13 06-24-2003, 11:03 PM

Thanks for all the replies. Will order from Fastlane.

wagonboy

#14 06-25-2003, 10:03 AM

Autozone has the Wahler German-made thermostat for this application. I believe it's about $15. Ordinarily I would agree that you should largely steer clear of some of the mass-retailers for Mercedes parts but the Wahler thermostat is a good one. One thing I should point out though, should you choose this route. The thermostat is mounted on a card which has the Autozone label on it. The thermostat, however, is stamped Wahler.

Rick Miley · #15 06-25-2003, 11:20 AM

Just for the record, I bought a gallon of genuine Mercedes-Benz coolant at the dealer a couple weeks ago for $10.50. Price is not a reason for not using MB coolant.