Mercedes Benz citric acid flush

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TLDR: Many folks seem to have good luck with the stuff so I figured I could give it a try with my Blazer before replacing the heater core. Is this stuff something that should be ran for a week or just a few minutes like other flush products? Thanks. Additional info: My main issue is that I know the system wasn't properly flushed for the transition from Dexcool to traditional green and that it takes forever to get to temperature. (For example, 15*F is horrible.. It takes forever with the heat off and about 7 miles with the heat on.) The thermostat is a NAPA (US made) 195*F. I also want the system clean before going through the hassle of replacing the heater core. I have replaced the coolant twice since ownership and performed 1 garden hose flush. Currently using ST traditional green.
 
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First of all don't waste your money on the MB stuff, its a ripoff, get this, double the amount for half the price with free shipping. Same product and just as effective. https://www.amazon.com/Citric-Acid-Powde...VAHD7CBND3PWDQA Usually 1lb dissolved in 5 qts of warm water is about right. Remove the thermostat and replace the housing then fill the solution in. Top off with warm water and run it for 10-15 min then flush it out. Its easy to flush with the thermostat out.
 
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Originally Posted By: Trav
First of all don't waste your money on the MB stuff, its a ripoff, get this, double the amount for half the price with free shipping. Same product and just as effective. https://www.amazon.com/Citric-Acid-Powde...VAHD7CBND3PWDQA Usually 1lb dissolved in 5 qts of warm water is about right. Remove the thermostat and replace the housing then fill the solution in. Top off with warm water and run it for 10-15 min then flush it out. Its easy to flush with the thermostat out.
Great tip; thanks!
 
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dlundblad, Just a quick note; it seems the cooling system is really good on the S-series trucks. I had the same problem during the winter and the solution was to block off the grille at anything below 20*. It would get stone cold going down the mountain with no throttle input before. Something to think about if the flush doesn't change anything
 
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The other thing is to use a marine stainless steel thermostat. No competition with surrounding aluminum surfaces. A thin film of Black Super RTV around the edge of the T-Stat when you set it in place will help block any side leakage. But yeah, in cold country, you need to block the radiator too. Plenty of surface area on the block and sump to "leak" heat away ...
 

dlundblad

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Originally Posted By: Trav
First of all don't waste your money on the MB stuff, its a ripoff, get this, double the amount for half the price with free shipping. Same product and just as effective. https://www.amazon.com/Citric-Acid-Powde...VAHD7CBND3PWDQA Usually 1lb dissolved in 5 qts of warm water is about right. Remove the thermostat and replace the housing then fill the solution in. Top off with warm water and run it for 10-15 min then flush it out. Its easy to flush with the thermostat out.
Do you recommend dumping the existing coolant and refilling with water or is the citric flush okay with the coolant? Not sure how big my system is, but I'll probably use 2 lbs. (10+ quarts)
 
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Originally Posted By: dlundblad
Originally Posted By: Trav
First of all don't waste your money on the MB stuff, its a ripoff, get this, double the amount for half the price with free shipping. Same product and just as effective. https://www.amazon.com/Citric-Acid-Powde...VAHD7CBND3PWDQA Usually 1lb dissolved in 5 qts of warm water is about right. Remove the thermostat and replace the housing then fill the solution in. Top off with warm water and run it for 10-15 min then flush it out. Its easy to flush with the thermostat out.
Do you recommend dumping the existing coolant and refilling with water or is the citric flush okay with the coolant? Not sure how big my system is, but I'll probably use 2 lbs. (10+ quarts)
Flush it through with fresh water first with the thermostat out, a garden hose is okay. For a 10qt system 2lb is correct.
 

dlundblad

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Thanks everyone. My plan is to undo the lines and rinse the system and core with the initial garden hose flush, but the old heater core will be bypassed during the citric flush. It's coming out so there's no need to waste the chemical. The original rinse is just so it doesn't pee coolant everywhere on it's way to the recycling can... Lol
 

dlundblad

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Originally Posted By: Trav
First of all don't waste your money on the MB stuff, its a ripoff, get this, double the amount for half the price with free shipping. Same product and just as effective. https://www.amazon.com/Citric-Acid-Powde...VAHD7CBND3PWDQA Usually 1lb dissolved in 5 qts of warm water is about right. Remove the thermostat and replace the housing then fill the solution in. Top off with warm water and run it for 10-15 min then flush it out. Its easy to flush with the thermostat out.
I plan on getting this too. She has Prime so it works out nicely. Thanks again.
 
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Originally Posted By: bdcardinal
So question about the linked procedure. I am assuming if you are replacing hoses, to do the R&R on them after the citric acid was drained?
That's the way I would do it, no point in running possibly grungy old water through them if you don't have to but it probably doesn't matter one way or the other.
 
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You do have to flush and degrease the system before doing a citric acid flush. If you have some real issues going on, don't follow the 10 minute advice. In marine systems, we run harsher acids for hours in badly contaminated systems. We have encountered failure of all types of acids to clear the damage of coolant cross contamination when run for less than 3 hours. If you're sure that is what it is, run it for a long time.
 

dlundblad

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Originally Posted By: DoubleWasp
You do have to flush and degrease the system before doing a citric acid flush. If you have some real issues going on, don't follow the 10 minute advice. In marine systems, we run harsher acids for hours in badly contaminated systems. We have encountered failure of all types of acids to clear the damage of coolant cross contamination when run for less than 3 hours. If you're sure that is what it is, run it for a long time.
Genuinely curious about a few things: This sort of severe cleaning would be from engines used in salt water though correct? I don't think the degreaser is necessary. No head gasket failures, oil intrusion etc.
 
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IMHO flush yes but degrease shouldn't be necessary in your engine. I just used it last week on a scale steam engine boiler, it worked slick as can be, nice clean boiler.
 
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Originally Posted By: dlundblad
Originally Posted By: DoubleWasp
You do have to flush and degrease the system before doing a citric acid flush. If you have some real issues going on, don't follow the 10 minute advice. In marine systems, we run harsher acids for hours in badly contaminated systems. We have encountered failure of all types of acids to clear the damage of coolant cross contamination when run for less than 3 hours. If you're sure that is what it is, run it for a long time.
Genuinely curious about a few things: This sort of severe cleaning would be from engines used in salt water though correct? I don't think the degreaser is necessary. No head gasket failures, oil intrusion etc.
No. Closed Cooled engines that run on engine coolant, same as a car. I say flush and degrease not for engine oil. Do it so your citric acid solution has less of a big job to do. Flushing and degreasing cuts down the bulk of the garbage. Also cuts out the coolant "film" off of the surface of metal and rust, laying it bare for the acid. Necessary? I suppose not "necessary", but I would not start this off by giving the acid a larger job than necessary. The reigning champion right now for worst cooling system cleaning right now was a 4.3 GM in a service pickup. That thing was so bad, we ended up ditching the radiator and running the citric acid through the engine and heater core separately using two buckets with electric pumps mounted in them, and a set of hoses. That was also a cross contamination case. Contaminated coolant turned to crystal. Inspired by the Honda procedure in which they flush the heater core separately to deal with heater core plugging. Worked like a charm. In your case, where you are replacing the heater core, I would segregate it from the rest of the cooling system so you are not attempting to clean what you are disposing of anyway.
 
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