Dr.Jeff
True Classic
Finished reading through the linked article. Since it is not directly from MB, a dealer, or a authorized MB repair facility, I did more researching to help validate the procedure described. Eventually I found the 'official' MB info from the workshop manual. Basically it is the same info, with slightly more detail and a little more dealer oriented regarding use of special tools, etc. I also found some added info from a MB factory rep that was questioned about the use of the procedure for non-diesel engines, what conditions it is intended for, etc.
Basically the MB citrus cooling system flush product is "citric acid powder". Based on my understanding of chemistry, there isn't a lot of difference in citric acids for something like this. If we were talking health care related use there would be long debates on the choice of product. But this application is not for human consumption so it really doesn't matter, any citric acid powder will work. The difference is what concentration (dilution) you mix it to. But I doubt you would need to spend the $50-60 MB wants for the official stuff. You can get generic, basic, industrial grade stuff cheap. The official MB dilution is a 10% solution. The size of the cooling system will dictate just how much powder that requires. But assuming you get 100% citric powder (not a mix of other elements), then a 1 pound bag will work for most vehicles (although the X has long connecting pipes, etc, its radiator is small, so about the same as a typical passenger car?). For general info on citric acid: https://en.wikipedia.org/wiki/Citric_acid
MB specifies this is intended to remove rust, scale and corrosion. For removing other residues (oils, etc, as when a head gasket blows) they recommend a alkaline cleaner at 3% solution. That is what the linked article used a laundry cleaning product for. MB sells a specific product for this as well. However it is not widely available and I haven't found much info on it yet. I'll have to do more research to see if the "Shout" is as effective.
One slight difference in the link, for the citric solution the MB manual says to run the engine at operating temperature for 15 minutes (rather than 10 minutes). However the MB expert cautions to avoid running it for too long as damage may result (e.g. freeze plugs come loose after excessive use). He also says it can be used for any engine, not just diesels, that need corrosion removal. Likewise the alkaline solution is intended only for oily film removal (10 minute flush time), so the two are not necessarily used in combination all the time. But for an old engine (especially with little knowledge of its service history) I think it would be best to do both, as the link states. In general terms this follows the earlier discussion about using a base and a acid for a complete cleaning process (as @Kendall said).
I have a good friend that is a factory MB tech with decades of experience. And he is very outspoken in his opinions about all things MB service. So I'll reach out to him and see what his take is on this. But it seems to be a safe method for a cooling system flush. It is similar to the use of oxalic acid for the same procedure. That has been a staple component for flushes for decades; mild acid, safe, fairly effective, affordable, relatively easy. It will be interesting to see how well the citric approach works, and how it compares to oxalic.
Thanks again to @Kendall for bringing this up.
EDIT: I forgot to mention another item that differs in the official procedure from the linked article. After using the citric acid solution, MB has a neutralizer product (a "silica element") that is placed in the system. I think a very thorough flush with water will suffice. However I feel the length of time needed to do that will be longer than the linked article states. In another document it is recommended to flush a system with water for 40 minutes after each chemical solution is used. That's a long time. But it might put things into a better perspective of what's needed to completely remove and neutralize the acid flush agent. I suppose you could also make a baking soda solution and run it through the system after using the acid. Then flush again with water. That's what I do when performing a oxalic flush.
EDIT #2: I've noticed the actual MB product (1.1 lb) can be found for less than $15, or as much as $50. I'm also seeing plain citric acid powder for about $2 a pound.
Basically the MB citrus cooling system flush product is "citric acid powder". Based on my understanding of chemistry, there isn't a lot of difference in citric acids for something like this. If we were talking health care related use there would be long debates on the choice of product. But this application is not for human consumption so it really doesn't matter, any citric acid powder will work. The difference is what concentration (dilution) you mix it to. But I doubt you would need to spend the $50-60 MB wants for the official stuff. You can get generic, basic, industrial grade stuff cheap. The official MB dilution is a 10% solution. The size of the cooling system will dictate just how much powder that requires. But assuming you get 100% citric powder (not a mix of other elements), then a 1 pound bag will work for most vehicles (although the X has long connecting pipes, etc, its radiator is small, so about the same as a typical passenger car?). For general info on citric acid: https://en.wikipedia.org/wiki/Citric_acid
MB specifies this is intended to remove rust, scale and corrosion. For removing other residues (oils, etc, as when a head gasket blows) they recommend a alkaline cleaner at 3% solution. That is what the linked article used a laundry cleaning product for. MB sells a specific product for this as well. However it is not widely available and I haven't found much info on it yet. I'll have to do more research to see if the "Shout" is as effective.
One slight difference in the link, for the citric solution the MB manual says to run the engine at operating temperature for 15 minutes (rather than 10 minutes). However the MB expert cautions to avoid running it for too long as damage may result (e.g. freeze plugs come loose after excessive use). He also says it can be used for any engine, not just diesels, that need corrosion removal. Likewise the alkaline solution is intended only for oily film removal (10 minute flush time), so the two are not necessarily used in combination all the time. But for an old engine (especially with little knowledge of its service history) I think it would be best to do both, as the link states. In general terms this follows the earlier discussion about using a base and a acid for a complete cleaning process (as @Kendall said).
I have a good friend that is a factory MB tech with decades of experience. And he is very outspoken in his opinions about all things MB service. So I'll reach out to him and see what his take is on this. But it seems to be a safe method for a cooling system flush. It is similar to the use of oxalic acid for the same procedure. That has been a staple component for flushes for decades; mild acid, safe, fairly effective, affordable, relatively easy. It will be interesting to see how well the citric approach works, and how it compares to oxalic.
Thanks again to @Kendall for bringing this up.
EDIT: I forgot to mention another item that differs in the official procedure from the linked article. After using the citric acid solution, MB has a neutralizer product (a "silica element") that is placed in the system. I think a very thorough flush with water will suffice. However I feel the length of time needed to do that will be longer than the linked article states. In another document it is recommended to flush a system with water for 40 minutes after each chemical solution is used. That's a long time. But it might put things into a better perspective of what's needed to completely remove and neutralize the acid flush agent. I suppose you could also make a baking soda solution and run it through the system after using the acid. Then flush again with water. That's what I do when performing a oxalic flush.
EDIT #2: I've noticed the actual MB product (1.1 lb) can be found for less than $15, or as much as $50. I'm also seeing plain citric acid powder for about $2 a pound.
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