Proper flush technique for coolant?
 

I noticed a new water pump on my truck when I bought it and a few days back I got a low coolant light. It wasn't too low, just enough to trigger the light going down hill hitting the brakes. Never did it again that day. I checked it the next morning and topped it off. There was a lot of brass/copper shavings in the reservoir stuck to the cap, floating about. It looks like they might not have flushed the system well enough when they did the water pump swap (hopefully it is not new shavings from something else).

What is the proper way to really flush this thing out and get it clean? Do I HAVE to take it to a radiator shop for a flush or can I do it well enough? I know it is not supposed to have bits floating about, but they are very small (just a lot of them) so do you think this will be an immediate issue? It's not really like having metal in the oil scraping the cylinders. I planned to do it as soon as possible. I guess a hung thermostat would be worst case if the bits affected it somehow?



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I flushed mine recently, including the radiator and engine block. Which engine do you have ? Mine's the 4.4 and it was a matter of removing a nut on the radiator plus two from either side of the engine block. However, one of the nuts on the engine block was inaccessible to I could only remove one of them.

So shavings in your coolant ?? Mmm .... I too hope it's only some debris left from switching the pump. When you've drained the rad and block, run loads of fresh water through the system and watch out for any more shavings that might wash through.

I used a standard coolant from the local auto accessories shop (50:50 coolant and battery water), however someone on here mentioned that there was some sort of special coolant to be used which prevents corrosion in the system.

It's not a huge job to be honest.

The only thing I can think of that actually has moving parts is the water pump so that's really all it could be IMO and the truck does have a new pump and TB on it. It's shiny and pretty. :D

So remove three bolts and flood the engine like a river with a hose. Are the coolant lines a straight shot through? It has to stop at the thermostat somewhere, which case it won't clean on the other side of it.

Maybe do the cleaning, do 100% water and just get the engine warm enough to open the thermostat, shut it off and let it cool then re-flood everything?

That's a good point which I had forgotten about. I had removed the thermostat at the time I did mine because I was replacing it.

But I like your idea about warming it up enough to open the stat. Sounds like it would work .....

Re. the moving parts. Yes the water pump impeller is the only moving part I can think of as well. I guess any grit/dirt present through age or corrosion in the system may also be in it. Possibly the coolant hadn't been changed in a long time before the last change so it may be flushing itself out.

Are you familiar with the pleeding procedure by the way ? When refilling the system.

I've burped my other BMW's through their coolant changes (fill, warm it up, cut off and let it open the stat through heat soak, restart and top off while running as it circulates) with no issues so unless this takes a special procedure of being blessed by a tribe of African Pygmies while filling the cooling tank I think it'll go pretty smoothly. :) ..........but feel free to enlighten me as it has been since '06 since I burped my last E36.

Ha .... good one ! This is a BMW after all so you never know. Africian Pygmies may be called on for something ....

But no, what you described is what I was thinking. Nothing unusual here.

If you really want to get as many shavings out as possible I'd probably pull the t-stat off (just 3 10mm bolts) and shove a hose in that bitch with the block drain bolts out. And the same with the radiator, maybe with the lower hose off in addition to the drain plug. As for the expansion tank, might have to just pull it out and hose it out separately.

For bleeding, just remove the plastic bleeder screw when you fill it and don't stop till coolant comes from both holes. (BMW was smart enough to put bleed screws at the highest point in the system on most modern engines)

To be honest, I have no idea. There are those who preach everything about specific fluids only for this, that and the other. Including coolant.

Personally I use standard off the shelf 5 litre drum full stuff. Again someone is likely to jump out of the bushes here and tell me I'll blow my radiator right through my engine block with all the damage I'll cause .... but I never had any issues with using the standard stuff.

:dunno:

The only real differences in any of the coolants of any importance is the PH level and the acidity. Steel engines with steel heads just need something to prevent freezing and rust, but engines with aluminum blocks, alusil sleeves, magnesium blocks on newer models and more plastic parts than ever before should have the correct coolant. A regular coolant will work for freezing, but the stable life of the plastic parts may be affected and the different metals in the system may not be as well protected from corrosion. So will your radiator explode, no... but the overall longevity of the components in the system may suffer.