Has anyone had experience using Prestone Super Radiator Flush? I'm not sure if I need to go all out and use the citric acid, and that procedure does require a special "stuck open" thermostat tool IIRC.

We just flushed my dad's 1992 300D. We didn't use any type of chemicals at all. Just drained the fluid and put a hose in the coolant tank and let it flow for about 20 minutes. At one point also we closed the drain plug and started the car for about 120 seconds. We then drained the water and began to fill it up with Mercedes Coolant which is required due to the aluminum head. I probably should have used some type of chemicals but I never had any overheating problems; just a preventative. My father also changes the coolant in his cars once a year.

Later

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Audi TT

For my 240D, the Prestone flush kit with hose hookup works very well. It can be moved from the cooling line under the air filter to the return line behind the cylinder head for power flushing the cyl head galleries.

My favorite flush chemicals are Valvoline 8-hour engine flush - great stuff for any kind of road trip. You will litterally see the engine cooling system become more efficient.

Then use Prestone Orange (not the green stuff) because Orange formula more closely resembles MB specs.

1) The Prestone stuff should work fine. Follow the directions on the bottle. Be careful about not putting any cool water, antifreeze, or cleaning solution into a warm engine! Easy trick to cool it down is turn the heater & fan on 'max' with the engine off. Assuming your aux coolant pump (under the washer bottle) is working, it will circulate coolant through the heater core and get the enging temps down rapidly... 20-30 minutes should get it to the ~50C range on the gauge, depending on ambient temps.

2) PLEASE don't anyone use Prestone antifreeze in a Mercedes, especially with aluminum or plastic parts present (most 1980+ models). The proper stuff is the MB/dealer antifreeze, or Zerex G-05, which are the same product in two different bottles. It's a light yellow in color. The orange stuff is a "long life" product, similar to DexCool (aka 'DeathCool'). Very bad - don't use - bad juju. The proper coolant is only ~$9/gallon, it's not worth saving maybe $5 every 2-3 years to use Prestone, now is it? G-05 is available at almost every auto parts store in a gold colored jug. More info on coolant types is at these 2 links:

http://www.w124performance.com/docs/general/Coolant_Confusion.pdf
(600kb PDF file)

http://www.w124performance.com/docs/mb/other/antifreeze_article.pdf
(1.7MB PDF file)

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Dave
Boise, ID
Check out my website photos, documents, and movies!

There is also a Prestone Heavy Duty flush that uses a powder (probably citric acid or something similar) and then a neutralizer. I've used it in tractors and also in my car and it seemed to work very well. Not much came out of my car but all kinds of crud came out of my tractor

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k

Heh, don't worry Dave! I filled up (10 quarts) with a 40/60 mix of Zerex G-05 and water, and a bit of Redline Diesel Water-Wetter. So far all is well!

got my cooling parts---> doing the flush

The manual has very specific instructions for a flush and coolant change. This is worth a read.

Thanks for the tip - ZEREX G-05 - but i think y'all are nuts for not doing a chemical radiator and coolant system flush at least twice a year..... say on the first hot sunny day in Spring and on the last warm sunny day in Autumn - its an easy backyard chore and the Prestone flush kit lets you pressurize and backflush the sytem after nuking it with chemicals and then working with the engine stone cold. Gotta pull the thermostat too for best results and naturally wrap all electrics and disconnect the battery because flushing the system makes one helluva mess which in itself is fun. Can also be combined with cleaning the engine bay using whatever solvents you've got on the shelf.