Orange growth in coolant system.

[Wingnut]

1988 325is: My Heater hasn't been working very well lately. I've tried to bleed but nothing came out of the bleeder. finally I popped off the thermostat housing and found this soft orange crud. Some of it had hardened in the bleeder hole. Does anyone know what this crap is?

[Wingnut]

Oh, I've been bad and have been using water only.

[Fourbanger]

Rust.

[FLG]

Oh, I've been bad and have been using water only.

You just answered your own question.

Sent from my Galaxy Nexus using Tapatalk 2

[jlevie]

That is rust and it is present because water only has no corrosion protection. If you think the thermostat housing looks bad, think about what block, radiator, and heater core, etc. must look like.

This can probably be fixed. You will need to source some oxalic acid, a couple of pounds will probably be enough. Add about 8oz of acid to plain water and run the engine for 30 minutes with the thermostat removed. Dump that from the engine and flush several times with plain water until the water drained is clear. A flush in this case means filling the engine, running until it reaches normal temperature, allowing it to cool until you can place you hand on the head w/o discomfort, and then drain the water from the block and radiator.

Repeat the acid & flush until you no longer get trash in the drained water. Then fill with water and add 1/2pint of baking soda. Run the engine at least twenty minutes, drain and flush as above.

To complete the job, replace the radiator, expansion tank, cap, water pump, thermostat, heater core, heater valve, all hoses, and fan clutch with new (not used) parts. Then fill the system with BMW coolant mixed with distilled water.

[Wingnut]

You guys think rust? Whats holding it together? Its kinda like tooth paste consistency.

Thank you all for the help!

[bastianshaw]

Jim where do you source oxalic acid?

[agent]

You guys think rust?

If Jim says it's rust, you can be pretty damned certain it's rust.

[vpilarrt]

Its a toothpaste consistancy because what you are looking at is wet rust deposits from the cooling system. The thermostat housing itself is aluminum and thus will not rust so you are seeing rust particles that have seperated from the water jackets in your iron block.

[dnguyen1963]

How difficult is this...?

http://www.ask.com/answers/83546261/who-sells-oxalic-acid