2015 2500 6.4 Coolant Overflow at Reservoir

[Mike Duckmanton]

New problem to me

2015 2500 6.4 122k

We had a cold spell was about to hit a couple months ago, so I checked antifreeze in all my junk. This RAM was in spec for temp, but took maybe a quart in the res to bring it up between the MIN/MAX

Fast forward to about a week ago, and several hundred miles after the top up, and I came out from running an errand to find a puddle of antifreeze under the truck and a small trail where I had parked.

No abnormal temps, I leave the engine info up on the EVIC constantly to keep an eye on everything.

It's been a week or so since it puked, and tonight I'm coming home from an errand and smell coolant, got to the house and it drops a some coolant out again. I did notice that the res cap wasn't tight.

Let it idle in the driveway for 10 minutes, revved it up a few times, still normal temps. No coolant in the oil. No bubbles or pressure that I could tell in the res.

Could it just have been a loose cap? I had seen reports of tanks splitting, I don't know if that's really a thing.

I do have a head gasket test kit that will tell me if there's gasses in the coolant, I'll probably do that tomorrow.

 

[crash68]

The 6.4 has a degas tank and if the cap doesn't hold pressure correctly it can cause issues with the coolant level. You might want to buy a new OEM cap for the tank.
If you start loosing coolant with no trace and/or puking coolant then the EGR cooler might be to culprit.

 

[mtofell]

My 2014 has always had a faint coolant smell which is a common complaint with these trucks but I've never been low any as far as I remember and never had any puddle or overflowing. I do have all my oil changes, etc. done at the dealer so it's possible they've topped it off and I didn't catch it in the paperwork.

@crash68 advice is spot on. Keep us posted.... I think the best chance is that it's just a fluke due to a loose/damaged cap. I've been hanging out here since I got my truck 10+ years ago and honestly don't recall a single post about a head gasket.

 

[Mike Duckmanton]

Sounds good fellas, thanks for the help

I'm going to get a cap ordered up, and see what happens

 

[2003F350]

Yeah the 6.4 is notorious for having a slight coolant smell after running hot for a while. I drove mine for 110k (a 2017) and every now and then would smell something but never saw evidence of a leak. I would check about once a month and never had the coolant be low enough to worry about, either.

I did see it look SLIGHTLY low a couple times on very cold days (-10 to -15 °F), but not enough that I wanted to add any. Remember that your coolant is roughly 50% water, and water actually SHRINKS as it gets colder - which means your coolant may have been fine and simply contracted. When you added coolant and it all heated up, it overflowed due to too much in the system. AGAIN, this is a guess, may have no bearing in reality, but is plausible.

As said above, keep an eye on it, if it doesn't lose coolant you likely don't have an issue.

 

[nlambert182]

One thing nobody mentioned.... a few years of these trucks have experienced a hairline crack and the molded seams on the tank itself. It's difficult to see in the truck, but will cause puddling. I replaced the one on my 3500 for that reason. You may want to pop out the fender liner and make sure you don't see coolant reside at the seam. It's not very expensive nor difficult to replace if that's the issue.

 

[bigdodge]

Definitely replace the cap.