its amazing what a simple ingredient can do, - its far better than any store bought coolant flush. I recently did it on a camry 2012 - the car was overheating, after a full drain and refill with citric acid flush and driven for 20 minutes I drained what looked like white paint from the radiator, heater core and cylinder block.

Its running perfectly now - for far less than a rebuild of the engine that the dealer recommended.

I also have made a manual flush system with a 5 gal bucket and a bulkhead connector which is sat on a ladder and I use that to force distilled/RO water through the system to flush the acid out of everything.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Thank you, you've proven my point .

I know what I'l talking about when I reply most of the time, it's why I don't respond to so many interesting threads : gaps in my actual hands on knowledge .

When I suggest a path to take, it's because i've been down it and know it works .

IMO one should ask questions and carefully evaluate all the given answers before making up one's mind .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

There is something I'm not getting, and that is why the process wouldn't work just fine with the thermostat in place, not blocked open. If you drive it for 20 minutes, should get warm enough to circulate all the fluid. I would think. Also I don't get why blocking it open would somehow be preferable to removing it. Not trying to give you grief in any way, it's just puzzling.

__________________
1986 300SDL, 362K
1984 300D, 138K

With the thermostat closed, the water pump only recirculates water through the block. If you have water in the block, it will only recirculate that until the thermostat opens and begins to circulate the acid solution. While you can do that, it's going to leave the acid in the system for a long time to do the same job compared to a blocked open thermostat.


The thermostat in a bypass cooling system does 2 things:
1: It opens the port for circulating coolant through the radiator.
2: It CLOSES the port for recirculating coolant through the block.


With no thermostat in place, you're recirculating a large amount of coolant through the block that normally should be circulating through the radiator and getting cooled. The result is rather rapid overheating, especially if you have lime in the radiator causing a restriction.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Ehh yeah that's bull ****. OM603 doesn't overhead without a thermostat. My thermostat failed shut and nearly overheated the engine. I removed the thermostat and drove it 400 miles until I found a good replacement. Temp gauge hovered around 60-70c depending on the speed.

__________________
CENSORED due to not family friendly words

If you dont have a stuck open thermostat, find a rubber cork that will fit into the round hole you see in the water pump housing when you remove the thermostat. Once this is blocked closed, The path of liquid is 100% engine to radiator.

so the procedure goes like.
drain from both taps
remove t stat
shove cork into bypass porthole
install tstat cover back without t stat in place (but some gasket to seal the thing)
fill up with acid mixture making sure no air is trapped
start engine run at 2000 rpm for 20 minutes.
let it cool off
drain the acid from both taps - leave them open
remove the t stat cover and cork you shoved in
remove a heater pipe - and shove a garden hose at low pressure into it to flush the acid out from everywhere. (or use the contraption I posted above)
install T stat and cover.
fill er up with coolant mixture.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Why not stick to the FSM and Mercedes standard coolants? Seems like the most logical solution. If your open to experimenting on a daily driver (I assume) then by all means post your results. (This goes to anyone)


Citric Acid is very cheap
Distilled Water is very cheap
G0-05 meets Mercedes standards and is reasonably priced.


Results: Working cooling system again without the threat of overheating/ doing it wrong.

__________________
Nosce Te Ipsum "Know thyself"

My thought is that the blocked open t-stat means that all the citric acid mix will immediately start circulating both through the engine and the heater core as well as the radiator, so less time is required to do the job. Also the flushing process is faster with the blocked open t-stat. Drain off the acid mix, fill with clean water, run the engine a bit, drain, refill, run engine, etc until you're happy that all the acid is out, then install the new t-stat and fill up with coolant.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

When I asked the dealer, they said not to use the citric acid in the newer engines. The ones with an iron head I think they recommended using it regularly.

617, 616 where iron headed.

Man imagine if the OM603 was iron headed.

__________________
1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

lol- so basically go with what I said to avoid confusing advice and damaging anything: drain, fill with distilled water, run till hot then drain when cool. Repeat. Fill with proper coolant.

Wrong .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Its not a regular procedure, only done when you have scale or debris in the system. e.g. the camry I wrote above. Toyota has no procedure in their FSM for a cleaning of the system and they even mention to use coolant to "flush" the engine. - Yeah right, waste 100 dollars of their premix pink to flush an engine which has scale stuck in its cooling channels. - Like saying you can wash an electric kettle with running water.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Doing that just now on my 1985 300D. Years ago, I bought 10 lb of citric acid off ebay. I use ~1 lb in water for a flush, as most recommend. You can occasionally find it in flushes at auto parts, and what Prestone Super-flush used to be, but many flushes are wimpier today. Perhaps you could use lemon juice or such, but I wouldn't know how much or if it even compares. I thought of skipping the citric in my 1985 because I did it maybe 3 yrs ago, but was amazed how much more stuff came out after 2 days running with that. The water was dark and smelled rusty. Currently running straight water several times to flush out the citric.

Currently, I am trying to repair a slight coolant leak from the head gasket. I had to wait until it was big enough to find, but now see the tell-tale white residue at the interface behind the intake manifold. Once clean, I will fill with distilled water and an expensive block seal ($26 bottle) they describe as "liquid glass", but is probably just a silicate solution (like pottery glaze). Similar has sometimes worked for me in other cars. Of course, if that doesn't work, I may have to pull the head once I can't live with the leak anymore. I'll then thoroughly dry the block inside (heater core is isolated) and re-install Evans Waterless Coolant (as I do in other cars). Indeed, I could live with this small leak if Evans wasn't so expensive ($43/gal).

A different experience was when I had a heater-core leak in my 1984 300D. Replacing that is a mega-job, so a redneck fix was worth a shot. I rigged up an isolated circulation loop, using a M-B aux water pump, drawing hot water from a pot on a camp stove. I dissolved a similar block-seal in distilled water and circulated it for several hours, then dried it inside. As I recall, that sealed the leak for 6 months, but came back slightly. I then thoroughly dried the heater core insides - blowing puffs of air to carry water out in a spray, plus alcohol blow thru, then dried w/ air puffer for days in our hot summer. I rigged a plastic tube to spray silicone seal (gutter Super-Seal or such) thru it and let it cure. No more leaks since (~5 yrs) and I still have plenty of heat (didn't totally clog the core). I suspect that worked because the heater core wasn't corroded but rather the rubber gasket had just relaxed a bit. One poster here years ago found that after spending days removing the heater core, he just needed to tighten the crimps on the tanks, then re-installed it. My method is certainly worth a try. BTW, a new heater core cost ~$400 if you can find one. I would instead use a pure copper one for a Chevy because who needs plastic tanks w/ rubber seals buried deep in their car, plus the massive size and strange 3-tube arrangement in the Behr ones that might be needed in northern Germany.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Thank you Bill ;

I'd say that was more a hard core DIY than Red Neck job .

? What year / model / engine Chevy heater sore fits and how much if any modifications needed ? .

I have a Meyle W123 heater core I bought twenty + years ago still in the box, IRC it was made in Germany and was over $200 when I bought it .

I don't look forward to taking the dash off any W123 but the cracks bother me so maybe one day I'll pony up the $ (!! GASP !!) and do it, of course none of my current three car W123 fleet has weepy heater cores....

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better