Author Topic: Radiator Sludge? (Read 3363 times)

ClayW · « **on:** June 24, 2012, 09:08:08 PM »

What is causing this?

I have a one year old radiator and the coolant is less than nine months old. My M42 has about 150K miles on it. I used the orange Prestone stuff with a 50/50 mix of distilled water and never anything else.

In addition to fixing whatever caused this, I'm assuming that I need to flush the system and refill. Are there any tricks or tips to flushing the M42?

vonkamp · « **Reply #1 on:** June 25, 2012, 03:58:22 PM »

Dump it, flush, and get the BMW coolant in there. There is no substitute...

Turn heater on, replace plastic bleeder.

jrobie79 · « **Reply #2 on:** July 02, 2012, 02:49:16 PM »

bavauto sells a brass bleed screw...its awesome

ClayW · « **Reply #3 on:** September 24, 2012, 01:03:12 PM »

Quote from: jrobie79;113534

bavauto sells a brass bleed screw...its awesome

do you have a part number for that? I couldn't find it in their catalog.

deansweet · « **Reply #4 on:** September 24, 2012, 06:44:50 PM »

A guess here but probably caused when you didn't totally empty the BMW coolant and added a different type.
What you really need to do is simply run water through it a couple times to ensure you get rid of the mixture of 'different' coolant types. Yes, it's a pita, but you'll end up with this sludge every time if you don't. Need to ensure you keep the heater setting on dash to full heat every time you flush it. There's a bleeder bolt on passenger side of block, gehind the exhaust manifold that will help you drain it all after each fill/flush.

ClayW · « **Reply #5 on:** September 25, 2012, 08:06:27 AM »

Quote from: deansweet;116202

A guess here but probably caused when you didn't totally empty the BMW coolant and added a different type.
What you really need to do is simply run water through it a couple times to ensure you get rid of the mixture of 'different' coolant types. Yes, it's a pita, but you'll end up with this sludge every time if you don't. Need to ensure you keep the heater setting on dash to full heat every time you flush it. There's a bleeder bolt on passenger side of block, gehind the exhaust manifold that will help you drain it all after each fill/flush.

Thanks for the tip on the bleeder bolt.

I drained it and followed the instructions on a Prestone radiator flush product, which included running for ten minutes with that stuff, then ten minutes with water, then refilling. This was after I replaced the thermostat, which was sticking closed because of the sludge.

I seem to have stable temperatures now.

Thanks!

BimwadM42 · « **Reply #6 on:** September 25, 2012, 06:28:00 PM »

Prestone orange is their Dexcool formula.

Look into Dexcool, and it can be, to put it kindly, sensitive to certain conditions and react unfavorably with undesirable results, including sludge.

Stick with a HOAT coolant such as the BMW/old Saab/Volvo coolant (G48), or the Mercedes coolant (G05).

jrobie79 · « **Reply #7 on:** September 27, 2012, 09:53:14 PM »

when I re-did my coolant these are the steps I took:

drain all existing coolant (let neighborhood dogs stop by if they were thirsty)
fill with distilled water - drive around for about 15 miles
drain and fill with water with PEAK radiator flush (not radiator cleaner)
drain and fill with distilled water - drive around 15-20 miles on the highway
drain and fill with distilled water one more time - drive around
drain and fill with 50/50 BMW blue and distilled water with half bottle of water wetter

been about a year with no problems and no sludge