Coolant change, Only took 3 gallons of coolant

I did a coolant change on my 2007, 5.9. I carefully removed the plug at the bottom of the radiator and let it drain. I quickly flushed the radiator and put the radiator plug back in. I proceeded to refill the radiator with Mopar concentrate and added about 3 gallons. I thought I should add some distilled water and it only took 1.5 gallons of water. I drained out the coolant tank and refilled it with 50/50 mix. I thought that we could get a good drain by removing the radiator plug. Am I okay with the concentration I have now?

 

You're heavy on concentration! You should always premix before adding to system. Always have a gallon container around to mix with. Not sure how that will affect cooling.

 

IIRC my 2006 rad capacity was 28 qts, so to get to -34 below you would need to use 14 qts ( 3.5 gallons in a 28 qt system) of concentrated coolant, from the factory mine was mixed for -34 below zero, but when I changed mine I used 4 gallons concentrate rest distilled water to reach approx. -54 below zero, few go too that extreme like I did..

 

Yep looks like a healthy range in All data.

You would need to baseline what you have to see where you are currently.

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ZEREX HD yellow Nitrite free OAT that I just used does the best at 70% mixture, for freezing protection and boiling point.

So there is no one size fits all, the specs of each product tell the story.

 

I have the opposite opinion on these trucks where so much coolant stays in the block. For a drain and refill you would want to use premixed coolant, but the maintenance procedure is flush and replace, so premix won’t work with ~3 gallons remaining in the block.

I use distilled water and do several iterations of drain, refill, run until thermostat opens, and repeat. I use distilled water so it’s ready for concentrate when flushing is complete. Once I’m satisfied with my flush I drain the system. I then add 3.5-3.6 gallons of concentrate, and top off with distilled water. That puts the cooling system at 50:50 with the distilled water that remains in the block for the 28.5 quart system (29.5 total quarts with 1 quart in the reservoir) I put premix in the reservoir and any makeup after a few drive cycles in premix.

Does best for boiling and freeze protection, but pure water has the best heat rejection so you could run hotter with higher concentrations of coolant.

From the 2005 service manual

 

John, Do you think I should drain off some of the mixture and then add just distilled water?

 

Based on the info you posted above, and assuming your residual coolant was 50:50 I calculate you're at a 60% solution right now.

If you drain off 1 gallon and add 1 gallon of distilled you would be about a 52% coolant mixture.

The big if is the percentage of the residual coolant in the block, so if you were good before and didn't mix it during the flush that's where you should end up.

 

Thanks John! How do you drain the block or is there not a block drain? I started the engine very briefly to get any coolant out of the block. Not much came out.

 

I'd leave it alone, I used about 4.5 Gallon of concentrate including the Reservoir.
Everything between 50% and 70% is fine. With just 3 Gallons I don't think your over.

 

There isn’t a block drain.

Sounds like you started it with an empty radiator, so it didn't mix fluids. You’d be fine leaving it, but if you start noticing the motor runs hot then do a 1 gallon dump and refill with distilled water

 

I drove the truck aggressively today over 5o miles and the temp needle never moved off of 190*-195*

 

Take the guess work out of it by getting a refractometer.
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I've always been pleased when I tow at max weight and see the temperature rise to the ~207* point for a good stretch of miles. Burns off carbon buildup. Wouldn't want to see it up there all the time, though.

 

207° is full open on the thermostat, the more you see it there the longer the thermostat works properly. Trucks that rarely see the thermostat go full open have wear spots that develop on the thermostat and then they are slow to open and eventually won’t go full open.

215-217° is where the fan really kicks in and you can spend all day there with a 190° thermostat and never have a heat related issue.

 

From the above answer you see - leave it alone.

Mine barely cracks the thermostat on cruise with the 65% or so mixture.

Keep in mind, the cooling system of the Cummins is oversized by a fair amount, we don't need the last 2% of cooling capacity except for severe duty service.

 

I agree leave it alone. But test it again later down the road.Before any winter temps etc

 

I took AH64ID's (John) advise and drained a gallon off and replaced it with a gallon of distilled water.