Do I need to flush coolant?

atinybug · 10-25-2013, 11:15 AM

I think my water pump died last night, and when I opened my hood there was a bunch of water that had sprayed out of the cap on my coolant reservoir so I topped it up with bottled drinking water (distilled was unavailable at the gas station). I probably put in total about 1/4 of a gallon. When I replace my water pump, I read from some other posts on here that between 60% - 95% of the coolant already in the system will be drained out as part of the process. My question is do you think it would be a good idea to completely flush the system of the drinking water?

Wolf 335 · 10-25-2013, 11:27 AM

If you are performing this yourself then go ahead and flush it out.

If you are going to pay the dealer or a shop, i think its unnecessary as you will be charged for a collant flush when there's barely anything left inside

Artmasterx · 10-25-2013, 01:33 PM

Quote:

Originally Posted by atinybug

I think my water pump died last night, and when I opened my hood there was a bunch of water that had sprayed out of the cap on my coolant reservoir so I topped it up with bottled drinking water (distilled was unavailable at the gas station). I probably put in total about 1/4 of a gallon. When I replace my water pump, I read from some other posts on here that between 60% - 95% of the coolant already in the system will be drained out as part of the process. My question is do you think it would be a good idea to completely flush the system of the drinking water?

Some drinking waters are just filtered water without any minerals added back. I don't know which brands, but you can look for the mineral content on the label. As long as it doesn't have minerals added back, it is almost as good as distilled. So I would not worry about it in that case.

Even if you did add spring water, the level of minerals in a quart in the whole cooling system probably will not make a difference, as long as you don't use normal/drinking water consistently. But I am not a cooling system expert.

Meeni · 10-25-2013, 08:13 PM

If you just put a little it is not a concern. It will be flushed when the WP is replaced anyway.

Do not continue to drive the car with a failed water pump. It will overheat the engine and cause damage (anything from gasket failures to catastrophic engine damage).

Efthreeoh · 10-26-2013, 05:59 AM

Yes, your pump did die as you described the classic loss of coolant when it died. No issue with adding drinking water to the system to get it back on the road. Everyone gets over-concerned with not having distilled water in the system. Not using distilled water in a cooling system has long-term effects on the system (i.e. many years and many miles), not short term, so don't worry about it.

Get the pump and t-stat replaced ASAP. The WP replacement removes all but a few ounces of coolant in the engine block (not sure why BMW did not put a block drain in the N52/N54), so once the repair is made you'll have completely fresh coolant in the system. I recommend getting a new reservoir cap while your at it.

atinybug · 10-27-2013, 01:23 AM

Yea I'm not driving it, it's sitting on ramps in my driveway, waiting for a pump/t-stat from ECS.

10-25-2013, 11:15 AM	#1
atinybug First Lieutenant 78 Rep 375 Posts Drives: 07 e92 335i 6mt Join Date: Oct 2013 Location: Atlanta iTrader: (0)	Do I need to flush coolant? I think my water pump died last night, and when I opened my hood there was a bunch of water that had sprayed out of the cap on my coolant reservoir so I topped it up with bottled drinking water (distilled was unavailable at the gas station). I probably put in total about 1/4 of a gallon. When I replace my water pump, I read from some other posts on here that between 60% - 95% of the coolant already in the system will be drained out as part of the process. My question is do you think it would be a good idea to completely flush the system of the drinking water?
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10-25-2013, 11:27 AM	#2
Wolf 335 Brigadier General 2341 Rep 3,537 Posts Drives: 2007 E92 335i Join Date: Aug 2012 Location: GTA - Greater Toronto Area iTrader: (0)	If you are performing this yourself then go ahead and flush it out. If you are going to pay the dealer or a shop, i think its unnecessary as you will be charged for a collant flush when there's barely anything left inside
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10-25-2013, 08:13 PM	#4
Meeni Gateropode 329 Rep 2,848 Posts Drives: BMW 330i 06 Join Date: Apr 2012 Location: TN iTrader: (0)	If you just put a little it is not a concern. It will be flushed when the WP is replaced anyway. Do not continue to drive the car with a failed water pump. It will overheat the engine and cause damage (anything from gasket failures to catastrophic engine damage).
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10-26-2013, 05:59 AM	#5
Efthreeoh General 17201 Rep 18,691 Posts Drives: The E90 + Z4 Coupe & Z3 R'ster Join Date: May 2012 Location: Virginia iTrader: (0)	Yes, your pump did die as you described the classic loss of coolant when it died. No issue with adding drinking water to the system to get it back on the road. Everyone gets over-concerned with not having distilled water in the system. Not using distilled water in a cooling system has long-term effects on the system (i.e. many years and many miles), not short term, so don't worry about it. Get the pump and t-stat replaced ASAP. The WP replacement removes all but a few ounces of coolant in the engine block (not sure why BMW did not put a block drain in the N52/N54), so once the repair is made you'll have completely fresh coolant in the system. I recommend getting a new reservoir cap while your at it.
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10-27-2013, 01:23 AM	#6
atinybug First Lieutenant 78 Rep 375 Posts Drives: 07 e92 335i 6mt Join Date: Oct 2013 Location: Atlanta iTrader: (0)	Yea I'm not driving it, it's sitting on ramps in my driveway, waiting for a pump/t-stat from ECS.
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