There is a flush which uses a sump pump to circulate the flush over a long period of time. We had a discussion about it a few weeks ago. The search function on this website will locate everything you need to know about engine flush.

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84 300SD
85 380SE
83 528e
95 318ic

Rust isn't attracted to a magnet either, FYI. Surely there's a chemical out there that you could use to test which it is though. Phosphoric acid maybe? That'll turn rust black, for instance.

-Rog

I use the Evaporust for its intended purpose, I do have some I plan to use in a dirty cooling system in a BMW. Not the $30 radiator specific one, just some from my five gallon tub.

If you are heavily corroded... a coolant filter is smart.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

my experience with gelled coolant is in a GM FWD sedan, to clean that I used commercial grade cascade automatic dishwash powder a large cup in the whole system full of water after I removed all the coolant. Ran for half a day and then rinsed out with a garden hose with every drain opened up. (collect this nasty stuff - dont let it wash in the storm drain)

All the gelled stuff came out like slurry.

I have not tried this on older silicated coolants.

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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)

Right, it works, but it will keep coming back -- a year or so for a bit more to dislocate from the massive collection in the block and then cause some more problems.

Dkr.

then your best bet would be a coolant filter.

I had a fiasco with a camry which was killing water pumps like flies and turning the antifreeze coolant into oily slurry - the culprit was lots of stop leak. I replaced the radiator and pump then powerflushed everything out and charged fresh coolant mix. I did install a NAPA coolant filter with no SCA charge units as bypass between the heater hoses. Just removed it recently as the system is super clean now and more so that the filter setup is going in another vehicle for a cleanup job.

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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)

I have a Gano in-line coolant filter. It is and probably always will be an annual affair.

Dkr.

Hmmm...looks like there are a few issues here:
1) Poor prior maintenance
2) Possible head/head gasket/block leak (combustion gasses getting into coolant)
3) Possible use of various 'stop leak' products
4) Possible use of GM Dexcool that has deteriorated

No disrespect intended, but are you sure that the head gasket replacement cured all the cooling system issues? How close was the replacement head examined? I have missed a very small (almost microscopic) crack from an exhaust valve seat area into the cooling passage. (That mistake cost me a couple of thousand $$ and huge amounts of time.) Don't tear the engine apart, just check for combustion gasses in the coolant. There are cheap kits or you could use an emissions sniffer.

If the prior owner tried to 'fix' the undisclosed cooling issue with large amounts of 'mechanic in a can' and used what ever was on sale for coolant you will have a major challenge on your hands - good luck.

A gazillion years ago Prestone, Wynns, et al marketed 'flush & fills' using a fancy machine. It used a nice little plastic pump to push fluid through the cooling system via a plastic 'tee' installed in the heater hose and out through the upper rad hose. You can make your own using a bucket/drum and a 'flo-jet' type pump plus a garden hose. ('Flo-jet' type pumps use a plastic pump housing & impeller so they are relatively impervious to acids.) I am not sure what you'd push through the engine (bypass the rad & heater core). I think I'd try reversing the flow in an attempt to push the garbage out.

The Gano is like a tea strainer, the coolant filter Im mentioning is like a heavy duty truck setup and has a filtering surface area at least 50 times larger than the Gano one - and its a bypass setup meaning it wont matter if it gets 100% clogged too.

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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)