Adding coolant..

We had a whole group of our '17 KW's that where doing the same thing, including mine. Every week I was adding coolant. No visible signs of a leak. Called into the shop and was told that a batch of trucks all had transmission coolers leaking. The coolant collected on top of the tranny and couldn't be seen. 10 of the trucks had to have the transmission cooler replaced. No more leak.

 

My 15 Detroit hasn't required any coolant since they found the minor leak (pressurized the system) 12 months ago. So, no. There is no acceptable level of coolant loss IMO.

That's what the expansion tank reservoir is there for.

 

You people saying it's "normal" are nuts and only adding to the misinformation when somebody does an online search.

I'll tell you another secret ; most modern day mechanics are nothing more then parts changers so take what they say with a grain of salt

When my brand new company truck with a maxxforce was doing this the mechanics said it was normal, guess what ? It was a bad egr cooler and after a "real" mechanic diagnosed the issue and replaced the 3000k mile part it never used coolant for the next 300k miles until it went again.

 

No, it's not normal to loose that much coolant that quick. There probably is a small leak somewhere, lots of connections on new trucks and sometimes you get coolant, air, fuel, DEF leaks. It happens, they should have no issues fixing it under warranty.

However, water permeation is a real thing with silicone. It is totally normal to need to add coolant occasionally and is unavoidable with silicone hoses. Antifreeze concentration should be checked at services. Antifreeze itself does not permeate through silicone, but the water that is mixed with it certainly does. So as coolant gets low, it's also getting more concentrated. Most of the time unless there is an actual leak, distilled water is all that is needed to top it off.

Here's a video from Gates on permeation. I have never lost 5 gallons in a year like they say, 1-2 is common on our trucks running all silicone hoses. Most of the time, with no leaks, they just need water, not antifreeze.

 

Wow, almost everyday I learn something new here over the past 5? years.
I was always wondering where my coolant goes. I top up about 3 gallons a year. I could never find a leak. Since I have a APU, I didn't want to blame the consumption on the trucks engine.
But now I learned it's the silicone hoses.

Silicone is misleading in more than one aspect.

 

Ditto. Had a 2013 T680 and now a 2016 T680. Drove both brand new. Both consume about 1 quart of coolant per month with no visible leaks or milky oil. Couldn't figure it out, but other than that all is well.
Guess I'll get the concentration checked.

 

I think i'd be fired if i complained about losing 2 quarts every 50k miles. Constantly taking the truck in for warranty only to have them find nothing wrong.

 

That's good info on the silicone hoses. I remember he commented to that same effect a few years ago in another coolant thread. I have silicone hoses and always add a couple of gallons of extended life coolant over the course of a year. Had no idea the water was evaporating (or however it does it) thru the silicone and concentrating my coolant. I used to dump 50/50 pre-mix in there but anymore just dump a gallon of distilled water as needed.

 

Thank you GrapeApe!!! Mentioning the DEF system made me look further and indeed that's where I found the coolant leak on our T-440 Kenworth. I was scanning the ground hoping to find indication and never found anything... simple reason, in-floor heating was drying out the evidence.

Thanks again, PL

 

Lol@losing coolant being normal. I never have to put coolant in my old cat. Oil ever every now and then but not coolant