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#4444435 - 06/28/17 11:13 PM Performed the Citric Acid Flush With Great Results
DoubleWasp Offline


Registered: 05/21/12
Posts: 5236
Loc: Fort Lauderdale, FL
I recently picked up a Kymco People 250 scooter at a steal of a price. It was a steal because the owner rarely rode or paid any attention to it. I wish I would have taken "before" pictures of the thermostat housing, because the whole system was super rusty. Some genius had decided that "you don't need antifreeze in Florida" and put straight water into the cooling system. Electrolysis did the rest.

I flushed the system with fresh water for 20 minutes, and that blew out a lot of the loose scale, but the system's surfaces were still super rusty. I remembered that I had purchased some food grade citric acid off of amazon a while ago, so decided to make this my first experiment doing the citric acid flush. Why? I've used the CLR flush to good effect, but do not like how nasty the chemical is, or how hard it is to flush that stuff out when done. Mercedes-Benz is the pioneer of mainstream citric acid flushing, and they only flush out a block for 5 minutes with fresh water after doing a citric acid flush. No baking soda, no nothing.

Being a food, it is obviously going to be nontoxic in reasonable amounts as well, and biodegradable.

Here's what the inside of the thermostat housing looked like when all was said and done:



I replaced the thermostat at the same time, so in order to do a proper "before and after", I took the old thermostat and dropped it in a 10% citric acid/90% water mix for 15 minutes. Mind you, this thermostat was never subjected to flow or heat while it bathed. The rust you see on the thermostat is solid and caked. Not easily removable with a screwdriver.

Before:



After:



Although I did not photograph it, I did inspect the impeller housing interior, as well as the cylinder head water outlet as well. Both were sparkling clean. Nothing to be found at all.

Although MB recommends 5 minutes of fresh water flushing after a citric acid flush, I did mine for 15 minutes.

My complete procedure?

1. Drain and flush system using Prestone kit for 20 minutes.
2. Drain entire system. (this scooter has a drain plug on the impeller housing that lets it all out)
3. Remove thermostat.
4. Mix a solution of 10% citric acid powder and 90% water.
5. Fill system with solution, and run engine for 15 minutes.
6. Drain and flush system again for 15 minutes.
7. Drain system again, and fill with appropriate coolant/distilled water mix (40% Rotella ELC and 60% distilled, in my case)

Official Mercedes-Benz procedure:
Quote:
Drain the cooling system of all the old coolant
Remove the thermostat and replace it with a "forcibly-opened" thermostat p/n 000 589 63 00
Connect a flushing connection pipe (a tee) p/n 117 589 00 90 00 between the upper radiator hose and the radiator
Connect a tap water hose to the tool fitting
Open the surge tank cap
Set the heater to defrost on cars with automatic CC so the aux coolant pump runs
Start the engine and run it at 2500 RPM
Open all drain plugs and turn on the tap water to maintain a full cooling system at all times while the engine is runniing
Flush for 5 minutes to remove all old coolant
Shut off engine, shut off tap water, and allow cooling system to fully drain
Install radiator and crankcase drain plugs
Dissolve citric acid powder in 5 liters of water
Fill cooling system with solution and top off with water, bleeding as necessary
Install surge tank cap and start engine
Run engine for 15 minutes at approximately 2500 RPM and blip throttle occasionally
Make certain that coolant is flowing through radiator and heater core.
Open cooling system drains again and turn on tap water to flush cleaning solution from cooling system
Start engine and run at 2500 RPM for 5 minutes to flush all cleaning solution from system
Shut off engine and remove special tool from upper radiator fitting
Reinstall normal thermostat
Make sure that all drain plugs are installed and tight
Remove the surge tank, flush it separately, and reinstall it


People who do this themselves highly recommend first treating the system with a "Tide flush", using Tide laundry detergent to eliminate any oils that may be present. Eliminating oils is apparently a very critical part of the whole process.

You will hear complaints from some that had done the citric acid flush that a component in their system failed during the flush. Like any effective cooling system treatment, any part that is hanging on by a thread will ditch when exposed to a flush. If your system is held together by stop-leak, this will remove it, and leaking will resume. YMMV
_________________________
07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio

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#4444443 - 06/28/17 11:23 PM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
tomcat27 Offline


Registered: 06/25/09
Posts: 3564
Loc: Chicago, IL
good repair! I wonder why they ever switched out the FF coolant
_________________________
2015 Rogue, 2014 Sentra, 2001 Camry, 2005 Starcraft, 1998 Dodge B1500
1996 Sebring Jx, 1984 F150, 1970 Cougar, 2013 XT250, 2010 Vstar, 2014 CTX1300

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#4444583 - 06/29/17 07:25 AM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
bioburner Offline


Registered: 09/19/16
Posts: 1418
Loc: Minnesota
Many labels for citric acid for cleaning. I like using water softner cleaner as its reasonable for powder and fantastic for cleaning brass. I seen that the shelf rad cleaner is now citric acid too now. Was a local guy a couple years ago making big bucks selling the stuff as a clothes washing machine deodorizer and mildew remover. I add a shot to the dishwasher and it takes the minor rust color out of the machine.


Edited by bioburner (06/29/17 07:28 AM)
_________________________

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#4444793 - 06/29/17 10:37 AM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
bullwinkle Offline


Registered: 10/09/04
Posts: 7649
Loc: Cincinnati, OH, USA
Originally Posted By: DoubleWasp
I recently picked up a Kymco People 250 scooter at a steal of a price. It was a steal because the owner rarely rode or paid any attention to it. I wish I would have taken "before" pictures of the thermostat housing, because the whole system was super rusty. Some genius had decided that "you don't need antifreeze in Florida" and put straight water into the cooling system. Electrolysis did the rest.

I flushed the system with fresh water for 20 minutes, and that blew out a lot of the loose scale, but the system's surfaces were still super rusty. I remembered that I had purchased some food grade citric acid off of amazon a while ago, so decided to make this my first experiment doing the citric acid flush. Why? I've used the CLR flush to good effect, but do not like how nasty the chemical is, or how hard it is to flush that stuff out when done. Mercedes-Benz is the pioneer of mainstream citric acid flushing, and they only flush out a block for 5 minutes with fresh water after doing a citric acid flush. No baking soda, no nothing.

Being a food, it is obviously going to be nontoxic in reasonable amounts as well, and biodegradable.

Here's what the inside of the thermostat housing looked like when all was said and done:



I replaced the thermostat at the same time, so in order to do a proper "before and after", I took the old thermostat and dropped it in a 10% citric acid/90% water mix for 15 minutes. Mind you, this thermostat was never subjected to flow or heat while it bathed. The rust you see on the thermostat is solid and caked. Not easily removable with a screwdriver.

Before:



After:



Although I did not photograph it, I did inspect the impeller housing interior, as well as the cylinder head water outlet as well. Both were sparkling clean. Nothing to be found at all.

Although MB recommends 5 minutes of fresh water flushing after a citric acid flush, I did mine for 15 minutes.

My complete procedure?

1. Drain and flush system using Prestone kit for 20 minutes.
2. Drain entire system. (this scooter has a drain plug on the impeller housing that lets it all out)
3. Remove thermostat.
4. Mix a solution of 10% citric acid powder and 90% water.
5. Fill system with solution, and run engine for 15 minutes.
6. Drain and flush system again for 15 minutes.
7. Drain system again, and fill with appropriate coolant/distilled water mix (40% Rotella ELC and 60% distilled, in my case)

Official Mercedes-Benz procedure:
Quote:
Drain the cooling system of all the old coolant
Remove the thermostat and replace it with a "forcibly-opened" thermostat p/n 000 589 63 00
Connect a flushing connection pipe (a tee) p/n 117 589 00 90 00 between the upper radiator hose and the radiator
Connect a tap water hose to the tool fitting
Open the surge tank cap
Set the heater to defrost on cars with automatic CC so the aux coolant pump runs
Start the engine and run it at 2500 RPM
Open all drain plugs and turn on the tap water to maintain a full cooling system at all times while the engine is runniing
Flush for 5 minutes to remove all old coolant
Shut off engine, shut off tap water, and allow cooling system to fully drain
Install radiator and crankcase drain plugs
Dissolve citric acid powder in 5 liters of water
Fill cooling system with solution and top off with water, bleeding as necessary
Install surge tank cap and start engine
Run engine for 15 minutes at approximately 2500 RPM and blip throttle occasionally
Make certain that coolant is flowing through radiator and heater core.
Open cooling system drains again and turn on tap water to flush cleaning solution from cooling system
Start engine and run at 2500 RPM for 5 minutes to flush all cleaning solution from system
Shut off engine and remove special tool from upper radiator fitting
Reinstall normal thermostat
Make sure that all drain plugs are installed and tight
Remove the surge tank, flush it separately, and reinstall it


People who do this themselves highly recommend first treating the system with a "Tide flush", using Tide laundry detergent to eliminate any oils that may be present. Eliminating oils is apparently a very critical part of the whole process.

You will hear complaints from some that had done the citric acid flush that a component in their system failed during the flush. Like any effective cooling system treatment, any part that is hanging on by a thread will ditch when exposed to a flush. If your system is held together by stop-leak, this will remove it, and leaking will resume. YMMV


That's impressive-which citric acid did you use? The Mercedes, or something else like food grade citric acid? I still have some of the caustic/neutralizer left, but that stuff is pretty harsh & dangerous to work with, not to mention the environmental issues. EDIT:whoops, I missed the "from Amazon" part, I'll look for it there.


Edited by bullwinkle (06/29/17 10:38 AM)
_________________________
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#4447186 - 07/02/17 07:02 AM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
dlundblad Offline


Registered: 09/30/13
Posts: 9998
Loc: Indiana
Boo. I was going to show the photos to my girlfriend, but they aren't coming up anymore.
_________________________
03 Jeep WJ 4.0 199k Castrol Edge 10w40 HM Fram XG16
02 Volvo S60 2.4T 177k M1 0w40 Mahle OX149D
97 Chevy Blazer 4.3 145k Rotella T5 10w30 Fram TG3980


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#4448259 - 07/03/17 11:22 AM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
DoubleWasp Offline


Registered: 05/21/12
Posts: 5236
Loc: Fort Lauderdale, FL
I'm going to re-host them tonight. Apparently, Photobucket now wants $400 a year to allow 3rd party hosting. There's no way I'm going to go along with that.
_________________________
07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio

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#4448274 - 07/03/17 11:34 AM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
SHOZ Offline


Registered: 06/28/03
Posts: 5742
Loc: Illinois
I buy citric acid by the 50 lb bag off ebay to use in my water softener. Works great in the cars cooling system too.
_________________________
2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual

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#4468619 - 07/24/17 06:19 AM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
DoubleWasp Offline


Registered: 05/21/12
Posts: 5236
Loc: Fort Lauderdale, FL
Alright, going to get these pics back up.



_________________________
07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio

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#4468635 - 07/24/17 06:46 AM Re: Performed the Citric Acid Flush With Great Results [Re: DoubleWasp]
Shannow Online   content


Registered: 12/12/02
Posts: 39821
Loc: 'Stralia
Just an FYI...it's what we use in the power stations to clean the boilers after 4-8 yeas use.

(And when I build a 13 tonne liquid CO2 storage system back in 1991, we used citric to clean the copper brazed lines of heat scale...old mate was (allegedly) a chemical engineer, and had a wading pool of citric acid that he "pH" tested by taste)

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