E30 Coolant Flush/Overhaul

[Forrest 35]

Hi guys,

Have been busy replacing water pump, thermostat etc etc on Dad's M20 race car that we are building.

When the coolant was drained it was dirty and looked like it hadn't been changed for years.

Have noticed that most of the water and cooling hoses have what I could describe as orange, rusty, crunchy gunk stuck to the inside of all of them.

As a precaution, we have ordered replacements for all of the main cooling hoses and the smaller ones such as heater hoses etc will be soaked and blown out with compressed air.

Is there anything I can run through them to clean out this crap when the hoses are off the car, and when reconnected what can I use to flush through to lose the crap out of the system and/or do I need to leave the radiator disconnected to stop all the crap getting pushed through it

Just preventing any more damage that can/could have been done already and any pointers are appreciated.

Cheers, Nathan

Edited March 6, 2011 by Brams

[Forrest 35]

Nobody wants to help?

[huff3r 347]

At the very least id run a hose through from the thermostat housing, rinsing out your engine for a bit. Havent really done anything more than that on any of my cars. However I would recommend being careful with the radiator, as a blocked core can be annoying and costly!

[Forrest 35]

I give up.

[huff3r 347]

Tried google? "Cooling system flush" or similar?

[CamB 48]

I thought the last suggestion was a good one (flushing clean water through the engine by way of the thermostat). Turn the heater on to hot as well so it flushes the heater core.

You could try flushing the radiator separately, although not sure how successful it will be.

Edited March 7, 2011 by CamB

[leithcm 0]

While not in the business of racing cars (well, not since the 1970's anyway) I do know that when reconditioning an engine the one part nearly always neglected is the radiator. It is so simple and easy to have the top and bottom tanks taken off and the core cleaned out THOROUGHLY. A partially blocked radiator will stuff an engine good and proper. Imagine what a highly stressed racing engine would go like if the radiator is blocked off? It would fry itself in no time. Reading about all the gunk and crap in the cooling system tells me it is a MUST to properly clean the radiator - and I do mean by removing the top and bottom tanks, not just merely turning a hose on inside it!

[antil33t 90]

remove that draining bolt from the sump below the exhaust manifold and reverse flush the block.

I basically just pushed water through the system everywhere, used the compressor gun to flush the water out afterwards. reverse flushed the heater core (low pressure). (this was all with no radiator)

then lastly, I filled up with just clean water, no anti-freeze, (though you can't with a racecar??) and put a bottle of wurth radiator flush in (like 20 bucks from the radiator shop) ran that at idle through for 30 mins, then dumped the water, and flushed it all out again with the hose (though the waterpump was back on this time) then refill with 50/50 mix of antifreeze.

Edited March 14, 2011 by antil33t

[Forrest 35]

Cheers for the input. New hoses arrived today, so will just flush it and see what happens, it was only crunchy because it has dried, so in theory if it gets wet again and flushes through all should be good, and the critical cooling parts are being replaced plus hoses so alot can't go wrong, besides if this blows up a m52/m54 will be on the cards anyway so it's not all bad

[pureboiracer 0]

^just make sure you check the belts too eh, water pumps arent too effecient without a belt eh nath...

[Forrest 35]

^ Haha was waiting for that, you know how much I love weight saving, I just took it to the nth degree

No need to fret brand new belts going on all over the show too.

[MLM 57]

Vaugly remember somwhere you are meant to back flush the system ie push water through in the reverse direction the the water normally flows...