Citric Acid flush project - PeachParts Mercedes-Benz Forum

eatont9999 · #1 02-10-2012, 10:04 PM

Hey y'all,

I bought 5lbs of citric acid on e-bay for about $17. I have decided to go ahead and flush the coolant system as the PO has been running mostly water in the system for who knows how long. I am glad I bought the 5lbs! The lower rad hose crunches when I squeeze it, so I can only imagine the amount of crud in it. I disconnected the upper hose to inspect it and all I could see was a thick coat of brown inside. I did three flushes of tap water and it is STILL coming out dark brown. The 4th flush I added about a pound of citric acid to the water (mixed well with the butt of my maglite) and I will consider this a preliminary flush. The radiator is going to be replaced with one that is in better condition. The upper nipple on mine is broken off and half-assed JD-welded back on. It came off with the rad hose. JUNK! I got it monkey rigged back on but I won't be running any pressure in the system until I flush it and install the new radiator.

After the low concentration citric bath, I noticed some black bubbles coming from the expansion tank. As a side note, my tank is leaking, so I need to fix or replace it soon. It leaks from the forward mount point.

I will post some pictures of the nastiness. It looks like this will be a 2-3 times citric flush. I will follow it up with 3x tap water and 2x distilled water before adding the final charge of G05. I will try to replace as many hoses as I can. I have cabin heat issues as well but with the way this system looks, I would not be surprised of a heater core or monovalve restriction.

eatont9999 · #2 02-10-2012, 10:13 PM

Many thanks to mechmagcn. He is a gentleman and a scholar as he pretty much gave me an almost new radiator at cost to him. Buddy, if you are reading this, at least let me make up the shipping charges.

I want to get out most if not all of the crap in my system before installing the new radiator. I don't want to clog it because it looks pretty clean. If I can, I will run it with the last citric flush to make sure it and everything else is clean. New hoses will be installed with the radiator. I also need to source a thermostat, gasket, bypass hose, and potentially a cheap monovalve rebuild kit. Honestly, I may just bypass the monovalve for now until warmer weather comes. Unplugging the power to it makes no difference.

Diesel911 · #3 02-10-2012, 10:30 PM

Keep an Eye on the Temp Gauge. Sometimes particles of Rust can continue to break off for Months and Months and can plug even a new Radiator.

Also keep a Eye out for leaks as the Citrus Flush had been known to eat the Rust away from Freeze/Core Plugs and leaks result.

E150GT · #4 02-10-2012, 10:34 PM

buddy let me tell you of the crap that can come out of a cars cooling system. My dad ran straight water for who knows how long in his 95 f150 even though I told him not too. It was horrific! The expansion tank alone had a few inches of sludge in the bottom.. It left rust driveway stains.

eatont9999 · #5 02-10-2012, 11:13 PM

Quote:

Originally Posted by E150GT

buddy let me tell you of the crap that can come out of a cars cooling system. My dad ran straight water for who knows how long in his 95 f150 even though I told him not too. It was horrific! The expansion tank alone had a few inches of sludge in the bottom.. It left rust driveway stains.

Oh, Sh@t! I drained it in the parking lot of my apartment complex! It briefly crossed my mind that it may stain but I quickly said FROG it, it will wash away in the rain. Well, I guess it's MY parking spot, now! HAHAHA. Way to own it! That along with the oil, PS fluid and blood stains; who else would want to park there?

E150GT · #6 02-10-2012, 11:25 PM

yeah my spot has been marked with a little oil, diesel and diff fluid. Where do you get your water source at an apartment? When I topped off my radiator I had to carry two beer pitchers full of water from the 3rd floor!

eatont9999 · #7 02-10-2012, 11:39 PM

Quote:

Originally Posted by Diesel911

Keep an Eye on the Temp Gauge. Sometimes particles of Rust can continue to break off for Months and Months and can plug even a new Radiator.

Also keep a Eye out for leaks as the Citrus Flush had been known to eat the Rust away from Freeze/Core Plugs and leaks result.

Thanks. Good to know. I will have to keep a diligent eye on temps and coolant levels. I'm assuming that a freeze plug replacement in a MB is similar to that of most other vehicles. You pull the old plug, clean around the block hole, use tool to install new plug into hole?

eatont9999 · #8 02-11-2012, 03:00 AM

Quote:

Originally Posted by E150GT

yeah my spot has been marked with a little oil, diesel and diff fluid. Where do you get your water source at an apartment? When I topped off my radiator I had to carry two beer pitchers full of water from the 3rd floor!

Luckily I live on the first floor. I carry it in a 5 gallon bucket to the parking lot. I'll be using distilled water for the last few flushes to get the minerals out. I don't see any reason to waste money on distilled water right now as the system is full of crap anyway.

JHZR2 · #9 02-11-2012, 10:12 AM

if just water was run, Id be worried about lack of inhibitors/corrosion protection. Rubber hoses are designed to resist electrochemical activity, but in a pure water system, Id be concerned. If run for a long timethat way and crunchy, it might be smart to replace the hoses.

sokoloff · #10 02-11-2012, 12:25 PM

Proper method according to Mercedes is to ALWAYS deoil first even there is no evidence of oil in the system. The citric acid flush should not be done until after the deoiling. All deoiling amounts to is a cleaning/flushing with Liquid Tide or Shout.

bigblockchev · #11 02-11-2012, 05:51 PM

You might be in for some heater core fun after this is over, either plugged or leaking. Cheers Dan

eatont9999 · #12 02-11-2012, 09:21 PM

Quote:

Originally Posted by sokoloff

Proper method according to Mercedes is to ALWAYS deoil first even there is no evidence of oil in the system. The citric acid flush should not be done until after the deoiling. All deoiling amounts to is a cleaning/flushing with Liquid Tide or Shout.

I forgot about that. I make my own detergent, that should work, right?

The hoses will get replaced after the final acid flush. I don't see the point in running nasty crap through fresh hoses and a fresh radiator.

tbomachines · #13 02-12-2012, 12:51 AM

Quote:

Originally Posted by eatont9999

I forgot about that. I make my own detergent, that should work, right?

The hoses will get replaced after the final acid flush. I don't see the point in running nasty crap through fresh hoses and a fresh radiator.

Yep as long as its non-foaming. Foaming detergent will create too much air in the system. Non-foaming detergent will get rid of the oil and grime without making bubbles in every tiny nook and cranny.

eatont9999 · #14 02-12-2012, 01:32 AM

Quote:

Originally Posted by tbomachines

Yep as long as its non-foaming. Foaming detergent will create too much air in the system. Non-foaming detergent will get rid of the oil and grime without making bubbles in every tiny nook and cranny.

It foams less than Tide does. I just hope it isn't too cold out tomorrow so I can work on it.

All the crud in the coolant system could be accounting for my lack of cabin heat due to a clogged heater core. It could also be several other things but if I put my finger on the heater core, it is warm at the bottom and cold the rest of the way up.

It might help if I bypass the monovalve and reverse the direction of flow to the heater core during flushing. Does anyone know the input and output routing of the heater hoses?

eatont9999 · #15 02-17-2012, 05:29 PM

Update:
I pulled the monovalve and booster pump to test and clean it. What a contraption! I am debating leaving it out of the car and installing a valve instead. Most of the heater hoses should probably be replaced but I'm not paying $20 a hose for a car that should probably be in the junk yard. I still don't understand the two inputs and one output of the heater core.

I have done countless flushes so far and at least three de-oiling flushes. I am on my second low-concentration acid flush. The radiator finally broke at the upper nipple. I bought some PVC pipe and bypassed the radiator so I can continue flushing. I will have to watch the temps, though. When the system starts to run cleaner, I will install the new radiator and do the last acid flush and follow up with several water flushes.