Can I run water only in cooling system?

[Scott & Heather]

Thanks guys for all the help and advice recently. Engine is in and fully hooked up as of today. I want to start it tomorrow and begin burping the cooling system. I've done this before and it takes me a few days of driving the coach heat cycling it to get all the air out. My radiators have a slow leak when it's cold out. Like below freezing. Since my cooling system is drained, I was going to pull them and reseal now but I'm thinking I might do this in a cooler climate. It was 97°F here today with a heat index of 103°. It's just too hot to be wrestling radiators. I'd like to get on the road here and maybe tackle the rads when I finally get back north. Instead of messing around with 25 brand new gallons of Detroit powercool, can I just fill with distilled water and drive like that until I get to Pennsylvania?

[buswarrior]

Sure, so long as you don't shut it down, if you encounter late freezes, which is happening right now.

Happy coaching!
Buswarrior

[bobofthenorth]

Just so its been said, the reason we don't run straight water in cooling systems is twofold - obviously preventing freezing is essential but coolant additives also prevent corrosion.  Heat cycling is a pretty harsh environment that favours corrosion so you won't want to run it that way for long.

[chessie4905]

Add a couple cans of waterpump lubricant. You don't want to start developing rust. Nalcool may also work.

[lvmci]

Chessie, will it mix with the red coolant?

[chessie4905]

Don't know. Best to contact mfg.

[richard5933]

Color is not a reliable indicator of anything. Different companies are using different color standards.

[chessie4905]

You will need to know brand of red coolant for your inquiry.

[TomC]

Coolant yes is an anti-freeze, lubricator for the water pump AND a whetting agent that coats the metal to get better heat transfer. If you run straight water, there is a chance of overheating more likely than with coolant. With the amount of money, effort you've put into the new engine-why start scrimping now? Just put in the proper anti-freeze and not worry about it. Carry extra to top it off. When you do change the radiators, reuse the coolant-it is done all the time. Good Luck, TomC

[Scott & Heather]

Running distilled water right now for my leakdown tests and test runs. Coach runs amazing. Still working out some kinks but so far so really stinking good.