Beware of the citric acid flush - you've been warned - PeachParts Mercedes-Benz Forum

dieseldan44 · #1 03-19-2009, 12:24 AM

I went to do a citric acid flush today on the 85. Car is newish to me and it was time to get rid of the green coolant.

Did the flush by the book and after about 10 minutes with the acid in my radiator started to leak at the bottom. Drip, drip.... Great. This cooling system functioned 100% before the flush - held pressure for days, stayed right around 85 C.

The last time I did a citrus flush on my 82, it took out the water pump after about 10 minutes as well. I also snapped the neck off the radiator at the time, but that was on me.

So I don't know what the heck is going on here, but I sure as heck am not doing a citrus flush ever again. I followed the FSM to the letter, food grade citric and the whole nine yards. I know how to mix acids and prep solutions from my bio-d tinkering, so Im sure I did the procedure right.

Shame on me for 1.) doing the citric thing a second time and 2.) Fixing stuff that ain't broke.

So if you are searching for info on doing a citrus flush, you've been warned. If you system is working just flush thoroughly with water, put in G-05 or MB coolant and leave well enough alone. Tomorrow is radiator replacement day now for me. I just hope nothing else has been pushed to the brink, like the (gasp, tremble) heater core (12 hour replacement).

Now I see why the older guys get, the more they go by 'if it aint broke...' Im learning, fast.

dd

Oracle12345 · #2 03-19-2009, 12:28 AM

I did the flush on the 77 and didnt have no problems, looks like you had some defective parts or parts on the way out

pawoSD · #3 03-19-2009, 12:51 AM

I have never citric flushed any of our MB fleet and they all run fine at 82-84C even on the hottest of days. I do flush out the coolant with new every few years....but that's it.

Ian White · #4 03-19-2009, 01:10 AM

In my opinion, the citric flush is the biggest waste of money. I dont see why you cant flush the cooling system like all other cars on earth are done. I have always used standard green coolant and have never had a single issue. The only thing I have ever done is change coolant (every 25,000) and replace the rad. cap.

I don;t see or understand the purpose of the citric flush. What exactly is the textbook purpose?

Thanks!

LUVMBDiesels · #5 03-19-2009, 06:03 AM

All the citric acid did was remove the gunk that was plugging the holes in the radiator. When I did my 81 300SD the same thing happened. Be thankful that the holes were revealed in the driveway and not on the highway. In a 20+ year old car you have to be prepared to replace the radiator. The citric acid is actually weaker than the Prestone flush.

As far as using green coolant, it does not protect the aluminum parts like G-05 does. It is not approved by MB and should not be used. That could be the reason your water pump failed.

rs899 · #6 03-19-2009, 06:26 AM

I did a citric acid flush on my old VW Cabriolet that has a gunked up engine. I put a new Behr aluminum radiator on it and let the stuff soak in the system for a week. Now I have holes in the radiator. Be careful with that stuff.

mplafleur · #7 03-19-2009, 07:06 AM

Quote:

Originally Posted by LUVMBDiesels

As far as using green coolant, it does not protect the aluminum parts like G-05 does. It is not approved by MB and should not be used.

Were they not making these cars long before G-05 came on the market?

KAdams4458 · #8 03-19-2009, 07:35 AM

Tell me about it. I had a little brown gunk in the cooling system of my Chrysler. Thought to myself, "Hey self, let's flush this and get it nice and clean before refilling it with coolant!"

Rinse - Rinse - Flush - Rinse Rinse Rinse - Fill...

"Gee self, why is their coolant dribbling all over my shop floor? Oh, look! I have two leaking freeze plugs now!"

Crappy corrosion-prone freeze plugs for the lose! That gunk in my coolant system? Yeah, turns out it was stop-leak. My 57,000 mile car came with stop-leak in the cooling system.

Well, it still runs great... I just need to figure out how to replace the two $1.50 plugs without having to pull the motor.

dieseldan44 · #9 03-19-2009, 09:12 AM

Quote:

Originally Posted by Ian White

In my opinion, the citric flush is the biggest waste of money. I dont see why you cant flush the cooling system like all other cars on earth are done. I have always used standard green coolant and have never had a single issue. The only thing I have ever done is change coolant (every 25,000) and replace the rad. cap.

I don;t see or understand the purpose of the citric flush. What exactly is the textbook purpose?

Thanks!

The textbook purpose is to de-rust and de-lime the cooling system. Think vinegar in a coffee pot or tea kettle. At least here where I live we have well water with tons of lime in it, I clean my tea kettle every other week.

My point in this thread is to warn folks that doing this procedure comes with risks. You must assess the benefits vs. the risks for your particular situation. Don't do the flush the day before you leave for a vacation, etc, because theres a good chance (100% in my case) you will be replacing something.

Tons of rust scale came out just rinsing the system with water, not a hint of lime was in there. To be fair, I could have fertilized my garden with what came out of my 82.

I keep telling myself its good that this happened now, but all I can think of is what a dope I would feel like if my heater core started leaking because of this. I also have a feeling my radiator would have lasted tens of thousands of miles. It even stopped leaking (and held some pressure) after I put water back in and did the three rinse-and-repeats called for in the procedure.

dd

TX76513 · #10 03-19-2009, 09:31 AM

Your last thread makes your point clearer - and I agree. Using a citric acid flush on a properly maintained cooling system that has not been doped up with additives poses little risk. Then the opposite for one that has not.

Oracle12345 · #11 03-19-2009, 09:56 AM

Quote:

Originally Posted by Ian White

In my opinion, the citric flush is the biggest waste of money. I dont see why you cant flush the cooling system like all other cars on earth are done. I have always used standard green coolant and have never had a single issue. The only thing I have ever done is change coolant (every 25,000) and replace the rad. cap.

I don;t see or understand the purpose of the citric flush. What exactly is the textbook purpose?

Thanks!

to deoil, derust and de calcifi the cooling the system. You really shouldnt be using green coolant in MB anyways. MB coolant was designed to be used in the mercedes engines just like BMW has their own coolant for their cars. You can get away with using green coolant in the 616, 617 motors but cant in the 603 since it will it eat the casting overtime.

vwnate1 · #12 03-19-2009, 10:39 AM

It has worked for me on several old klunker Mercedes I bought that had thick red goop in the cooling system ~ if you found leaks , they were plugged with rust , that's not a fault of the flushing ! . it CANNOT DAMAGE anything ! .

I agree , if your 25 year old car has been properly maintained since new(rare)
then maybe this procedure isn't for you .

I also live in an area that has terribly bad had water that eats coling systems alive .

Hard Water is very good for brewing beer though , we have lots of micro breweries here for just that reason

75Sv1 · #13 03-19-2009, 11:03 AM

Quote:

Originally Posted by vwnate1

It has worked for me on several old klunker Mercedes I bought that had thick red goop in the cooling system ~ if you found leaks , they were plugged with rust , that's not a fault of the flushing ! . it CANNOT DAMAGE anything ! .

I agree , if your 25 year old car has been properly maintained since new(rare)
then maybe this procedure isn't for you .

I also live in an area that has terribly bad had water that eats coling systems alive .

Hard Water is very good for brewing beer though , we have lots of micro breweries here for just that reason

What is considered hard water in CA? I think the definition is anything over 7. In PA its like 14. In IN its around 23. I try to use distilled water in the radiator, if mixing coolant with water.

Tom

ds190 · #14 03-19-2009, 11:05 AM

Quote:

Originally Posted by mplafleur

Were they not making these cars long before G-05 came on the market?

Yes, MB was indeed making aluminum engines with plastic radiator parts before G-05 came out. That's why the auto came from the factory with the correct MB gold coolant!

G-05 is just a less expensive compatible version of the MB stuff, which is why I use it

LUVMBDiesels · #15 03-19-2009, 11:10 AM

Quote:

Originally Posted by mplafleur

Were they not making these cars long before G-05 came on the market?

The cars they were making up to the 1970's had bras radiators and no aluminum parts in the cooling system. They can take the green stuff. The ones that came after that like the ones most of us drive have aluminum radiators and aluminum water pumps. They need the G-05.

Green Stuff vs. Orange Stuff (Antifreeze)

By Steven Rae, email smrae2@comcast.net

Reprinted from the 500 Section Star, Steven Rae, Editor
Do yourself a favor right now. Go out and look at the color of the antifreeze in your Mercedes-Benz (Make sure the engine has cooled before opening the coolant cap). Is it by chance GREEN?If you have anything other than the pale orange Mercedes-Benz brand antifreeze in your cooling system, please read on because you may be harming your engine! As a bit of background, antifreeze is in many ways a miracle formulation, because it not only lowers the freezing point of water, it also raises the boiling point, assuming the correct 50/50 mix of antifreeze and water.
George Murphy, Chairman of the MBCA National Technical Committee (2000), strongly urges that only genuine Mercedes antifreeze (properly mixed with water) should be used in your car because it contains special additives to keep the coolant from eroding alloy engine components and harming plastic cooling system parts.Mercedes-Benz brand antifreeze contains buffers to keep the pH of the coolant as close to neutral as possible, which then prevents erosion and corrosion of engine parts. pH is a measure of the relative concentrations of acids versus bases in a liquid. Other name brand formulations, while claiming to be specifically formulated for aluminum engines, do not contain the correct pH buffers.
While genuine Mercedes-Benz brand coolant is a little more expensive at $10 a gallon vs. $6 for the "Green Stuff", think of it as extremely cheap insurance to extend the life of your M-B investment. Also note that Mercedes-Benz recommends changing the coolant at least once every two years. Promise yourself you will check your coolant and have it drained and refilled with the Orange stuff. Those of you with the correct fluid, pat yourselves on the back and worry about collecting your 155,000-mile pin.