[orion_squall]

Hi,

So my 2007 E92 N52 also got the common "oil filter housing gasket leak" problem.

Because of this problem, there is an unknown amount of engine oil in my cooling system. Beside the replacement of the oil housing gasket, the dealer strongly recommand the following:

1. extended coolant flush/remove oil from coolant passages
2. cooling system service. Clean the entire cooling system to stop acid and rust formation, lubricate water pump and thermostat. Remove of sludge, oil etc

Both together will be close to $1000 canadian dollar including tax.


Now here is my question. Do any of you know what are these two service? Should I bother doing a coolant flush myself following the DIY knowing that likely I still won't be able to completely clean all the residue oil and sludge from the coolant passages?

I have researched and found the follwing way to clean the cooling system, but I need more comments from knowledgable people:

1. During DIY coolant flash, put in disdilled water for a couple cycle and flush it out. This would be risky for canadian climate which goes to -20C in winter, any residual water would just crack every hose. In addition, I don't feel water will be able to clean out oil and sludge.

2. Use of coolant cleaner such as "Prestone radiator cleaner". My research so far found no indication of anyone using a such product on a BMW. So I worry that by putting it in, I immediately damage components of the cooling system.

Any other methods? comments?

Very appreciated!

[orion_squall]

To add:

There is a cleaner claims to be ok for all european cars "LIQUI MOLY Radiator Flush - Liqui Moly Radiator Cleaner (300 ml. Can)". Any comments on that?

[TheeGovernor]

Originally Posted by orion_squall

To add:

There is a cleaner claims to be ok for all european cars "LIQUI MOLY Radiator Flush - Liqui Moly Radiator Cleaner (300 ml. Can)". Any comments on that?

How bad of oil sludge mix did you get? If it isnt too bad, I suggest just flushing the cooling system a couple times with regular coolant. I dont like to use those cleaners because they always remain in the system after flushing.

[Nebo]

I had oily coolant and I flushed it three times and so far after 25k miles or so it's been super clean. I flushed it once with distilled water, filled with more water and drove for 30 mins then flushed again. Filled it up with 60/40 coolant and checked it once a week. Noticed that it stayed blue the whole time and called it good.

From my experience, a few flushes seems to be sufficient in ridding the oil.

[orion_squall]

Originally Posted by Nebo

I had oily coolant and I flushed it three times and so far after 25k miles or so it's been super clean. I flushed it once with distilled water, filled with more water and drove for 30 mins then flushed again. Filled it up with 60/40 coolant and checked it once a week. Noticed that it stayed blue the whole time and called it good.

From my experience, a few flushes seems to be sufficient in ridding the oil.

Thank you Nebo. Sounds like what you are suggesting is method 2 I have mentioned.

I do have a question about this common method: Knowing that winter in Canada can go as low as -20C, -30C and the DIY method shown on this forum probably flush say 60%-80% of total coolant amount. Is there a risk that I will ended up with too much distilled water by doing a "cleaning/flush" with water only? Or you have already considered this possibility by doing the 60/40 coolant to water ratio, instead of 50/50. So this way, you ensure that the extra coolant with mix with the remaining water and reduce the risk of freezing.

thanks

[Efthreeoh]

If it were my car, I'd drain the coolant, and flush it with detergent and water a few times, then rise it with plain water a few times, then refill with the correct BMW coolant/distilled water mix. The detergent will break up any oil molecules in the cooling system and flush them out suspended in the water.