Can I run the water pump on just distilled water?

[mosaud1998]

I'm planning on flushing out the coolant on my BMW sometime next week.

I don't really want to take off the water pump hose and the other hoses to let coolant out. It'll create a big mess, which I don't really want.

So, I plan on unbolting the radiator drain plug and letting all the coolant drain out the radiator. Then Adding 2 gallons of distilled water and bleed the system/ turning the water pump on without starting the car.

After I'm done bleeding the system and draining the water out, I'll add the 50/50 BMW coolant.

Can I harm the water pump or other coolant items by just bleeding the system with distilled water?

If I turn the water pump on when there's no coolant in the system, can I harm the water pump that way by running it dry?

Any other things I should be cautious of?

 

[jagdriver727]

No worries. The water pump has a sealed bearing. Fluid in the cooling system makes no difference.

I suppose over time the wrong liquid in there could potentially damage the seal... but for what you're talking about it doesn't matter.

 

[atikovi]

Coolant lubricates the pump shaft seal. Straight water, not so much. How much less, who knows but I'll drive an hour with just water and not worry about it.

 

[gathermewool]

What’s wrong with a radiator drain and refill?

 

[mosaud1998]

Coolant lubricates the pump shaft seal. Straight water, not so much. How much less, who knows but I'll drive an hour with just water and not worry about it.

I'm not going to drive the car. I can turn on the water pump without actually starting the car.

Maybe just a drain and refill every 2 years would be the better route. That way, I don't mess anything up

 

[mosaud1998]

What’s wrong with a radiator drain and refill?

Yeah, I think I'll just stick to a drain and refill.

Better to be safe then end up spending $500 and a whole week to replace the water pump and t-stat

 

[atikovi]

I'm not going to drive the car. I can turn on the water pump without actually starting the car.

Maybe just a drain and refill every 2 years would be the better route. That way, I don't mess anything up

Drain, refill with distilled water, drive until thermostat opens + 5 minutes. Repeat 5 times with the last refill being coolant. Then you're good for another 10 years/150,000 miles or whatever the manual says.

 

[gathermewool]

I believe the reason my Subaru manual requires a shorter interval on subsequent coolant changes is because they assume only the radiator is being drained and refilled, diluting the rest of the old coolant. This replenishes additives enough for, say, half the original interval.

 

[gathermewool]

Drain, refill with distilled water, drive until thermostat opens + 5 minutes. Repeat 5 times with the last refill being coolant. Then you're good for another 10 years/150,000 miles or whatever the manual says.

I used to do that. Too much work and too much waste liquid for me these days. I had access to the base hobby shop then, too. Now, it’s just me in my garage.

 

[atikovi]

I used to do that. Too much work and too much waste liquid for me these days. I had access to the base hobby shop then, too. Now, it’s just me in my garage.

Takes 2 hours to do it right for something you do once every 10 years. And its acceptable to pour it down the drain for residential quantities assuming you're not on a septic system.

 

[gathermewool]

Takes 2 hours to do it right for something you do once every 10 years. And its acceptable to pour it down the drain for residential quantities assuming you're not on a septic system.

I’m on septic...

I wouldn’t EVER consider pouring antifreeze down the drain, even if I was on city sewer. I hope you’re kidding.

 

[earlyre]

I’m on septic...

I wouldn’t EVER consider pouring antifreeze down the drain, even if I was on city sewer. I hope you’re kidding.

no... it's allowed on a municipal sewer... EPA says its okay!

 

[gathermewool]

Not in CT: “Used antifreeze should never be dumped down a drain, in the sewer or on the ground”

 

[earlyre]

Drain, refill with distilled water, drive until thermostat opens + 5 minutes. Repeat 5 times with the last refill being coolant. Then you're good for another 10 years/150,000 miles or whatever the manual says.

that's kinda what i did when i changed the coolant in my sable a few years back, but instead of distilled for the flushes, I used RO water. (local kinetico dealer has a "tap room" where you can fill jugs for a quarter per gallon.) and i spread it out over a week, because... i have the time...
Drain the Rad(open the petcock), pull the old thermostat, (after 10yrs/105k mi, why not, it's a
yes, I drove around for a week, in the summer, with no thermostat and mostly water in the cooling system. OH NOES!

 

[earlyre]

Not in CT: “Used antifreeze should never be dumped down a drain, in the sewer or on the ground”

Ohio EPA - Automotive Maintenance Products
"Disposal of Antifreeze :
The hazardous chemicals in antifreeze can be broken down in most sewage treatment plants. If you cannot recycle the antifreeze and your home is connected to a sanitary sewer system you may flush used antifreeze from your automobile down the toilet or sink. Be sure to wash it down the drain with plenty of water. If your wastewater goes into a septic system, do not pour used antifreeze down your toilet or sink, Antifreeze can inhibit organisms in a septic system, causing damage to the system. In this case, ask someone who is connected to a sewer system to dispose of your antifreeze for you."

 

[atikovi]

no... it's allowed on a municipal sewer... EPA says its okay!

County here says to do that as well.

 

[eljefino]

I did the earlyre drain & fill over a week on my cutlass ciera back in the day. Got a lot of junk out! A++ would recommend.

 

[Oro_O]

If you run your system with distilled water, then drain it fully, and fill it with 50/50, you will end up with much less than 50/50 protection.

There is water in the heater core and hoses, and other bends, that does not come out. If you flush, or do multiple drain/fills with water, you need to allow for up to a quart of water in your system BEFORE you start adding coolant. If you use 50/50, you end up with less freeze and corrosion protection. If you consider it comes out to 40/60 - a reasonable assumption -, that's still a 20% drop in additives and corrosion protection, and a 20F increase in the freeze protection (from -35 to -15F roughly) point. Not worth it at all. If you go the "full drain" route, you must refill with straight concentrate in a volume equal to 1/2 the total system capacity in order to get to 50% (or better yet, 60%). Then you top up it up in a second step with straight dH20.

If you don't really know exactly what's going on with a cooling system, play it safe and just drain the radiator. Refill that and then worry about it in a few more years.

 

[earlyre]

I did the earlyre drain & fill over a week on my cutlass ciera back in the day. Got a lot of junk out! A++ would recommend.

amazingly, after 10 years and 105k mi, that motorcraft Gold(G05) still looked basically new, no real crud to mention... but...it was "time"
modern coolants and all aluminum system for the win?

 

[atikovi]

If you run your system with distilled water, then drain it fully, and fill it with 50/50, you will end up with much less than 50/50 protection.

All the more reason to use 100%.