How to flush coolant system?

I have E30 316 4-cyl carb. BMW with 45000km (yes only less than 30000 miles). It was not in use for 7 years, and coolant was changed some three years ago.
Now (I think) I have problem with choke on my carburetor. I got it cleaned (ultrasound) in a local carb shop, and for a while it worked OK.
My problem: I start cold engine, revs go to ~1000 rpm, then after about one minute go up to ~1500 - 1600 rpm. But after five minutes or so rpm starts dropping, so when I stop in traffic its ~400 - 500 rpm, and sometimes just stales.
Since coolant is running trough the carburetor I suspect that choke system may be clogged, since engine runs OK once it's warmed up.
I have Bentley and Haynes manuals for E30, but I found no instructions on how to flush cooling system. I knew where are radiator and engine block drain plugs.
What is the right procedure to flush cooling system?
Let me just note that chemicals for flushing and professionals that can do that job is hard to find (at least I do not knew any) where I am.
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My first BMW was an '88 316 :-)

The Pierburg carb in this car is junk. Replace it with a Weber, better mpg and more power! Your may have a problem with the automatic choke.
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Nedavno John Burns pise:
| The Pierburg carb in this car is junk. Replace it with a Weber, better | mpg and more power! Your may have a problem with the automatic choke.
Maybe, but that is not easy to do where I am. I bought manual for my Pierburg 1B2 (still waiting for it to arrive), and I hope to tune so that it performs as it should.
But my main question was how to flush cooling system on my BMW. Anyone with suggestions?
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Nedavno Yvan pise:
| But my main question was how to flush cooling system on my BMW. Anyone | with suggestions?
Hire is what I thought:
- Turn heater knob on dash to hot. - Drain coolant, and live both radiator and engine block drain plugs open - Disconnect hoses from the carb (for choke operation), plug one of them, and connect garden hose to other - After a while plug other carb hose, and connect garden hose to first one - After a while put a garden hose into radiator - Close the plugs, and fill the cooling system with distilled water - Repeat last step few times - Fill the cooling system with 3.5 liter of 100% coolant (total capacity is 7 liter), and fill it up with distilled water.
And that should be it. Any comments?
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Yvan wrote:

This is what I used to do. But it's now illegal to let any coolant or the rinse water run onto the ground and into the storm drain. So now I just pay my mechanic to flush it with that pressurized machine that he uses.
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Nedavno Rhaspun piše:
| This is what I used to do. But it's now illegal to let any coolant or | the rinse water run onto the ground and into the storm drain. So now I | just pay my mechanic to flush it with that pressurized machine that he | uses.
Unfortunately where I am there are no such laws, and everyone disposes coolant the way he wants including mechanics. Usually it goes down the drain (as far as I knew). I will ask around if I can dispose of coolant safe way.
Thanks for your comment. Its is good to knew that I found the right way to flush, I will do it as soon as I this "Siberian" cold wave goes away.
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Do a little research and you might find that coolant is really not an environmental hazard. After a few days it is usually broken down by organisms in the soil or sewer systems. They spray essentially the same stuff on airplanes to de-ice all the time. The environmental effects have been negligible.
I asked the question of a friend at an environmental agency a few years back. The response, after a little research, was just to flush it down the sewer system. True, some places won't allow this, but it may be an over-reaction to the potential dangers. There may also be other additives in newer formulations that may be a problem. This I don't know. The EG is only a short term danger to any animals or humans that might ingest it.
Leonard

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Leonard Caillouet wrote:

<snip>
<snip>
You have identified the problem in the second excerpt, but you minimize it. Manufacturers of airplane deicing fluid do not make their recipes public - yes, it's mainly ethylene and propylene glycol, but there's a bunch of other stuff in there too. The airport in Toronto, Canada, has spent millions on a deicing facility that recycles the fluid instead of allowing it to go straight into the groundwater. They would not do this if it was harmless.
The same problem exists in automobile coolant- the recipes are top seekrit and the consumer and municipality has no idea what they're dumping into the sewer, which in most places goes with minimal treatment into the surface water.
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Nobody Important wrote:

Aircraft deicing fluid is VERY TOXIC, Ottawa Canada's airport also spent millions building an aircraft deicing center to recover the fluid, even if the aircraft are deiced on the gate a vacuum truck appears minutes after push back to remove the fluid. If a dog or cat drinks the fluid it will die within 24 hours of kidney failure. DO NOT leave an open container of this fluid in a place where animals can get to it as it will KILL them.
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