How much coolant...

Doublebase · September 7, 2019

How much coolant are people having to replenish/top up/add in let’s say a year or 20,000 miles?

I'm nearing 40,000 miles on my truck (2018 5.3 Silverado). I just topped up for the second time since I’ve owned the truck since new...it was maybe a 1/2-3/4 of an inch bellow the “full cool” line. And I was surprised at how much it actually took to fill it back up to full...maybe a quarter gallon/little less.

I’m not concerned - as I have zero overheating issues, smell of coolant, smoke coming out of my exhaust - and like I said, I’ve only topped up twice, but I’m just curious...what’s everyone else adding? And when do you plan to actually change your coolant...100,000 miles? More? Little less? I figure the system takes a couple gallons and I’ll just use Dexcool again when the time comes.

Snowcamo · September 7, 2019

Zero. Its a sealed system and you shouldnt have to add anything.

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SierraHD17 · September 7, 2019

As said above... none. If it's going down its burning it or leaking it.

Silverado/Sierra guy · September 7, 2019

Check for a small leak

Snowcamo · September 7, 2019

If you dont find a leak. Rent a bore scope and pull your spark plugs. One or more pistons should be carbon free and clean or very close.

Doublebase · September 7, 2019

So no one’s coolant has dropped at all from that full cool line? Not a bit?

I wasn’t concerned at all, still not, but I’ll check for a small leak.

I have certainly added coolant to many vehicles over the years that have closed systems...not a lot, but a little smidge here and there at oil changes.

CamGTP · September 7, 2019

Mines like 1 inch below the "full line" when cold, I just have never bothered to do anything about it. Hasn't moved from that mark since I've owned it.

davester · September 7, 2019

It may be slowly coming out the weep hole in the water pump. You might look underneath at the bottom of the water pump (may be to remove shields to do this, but I don't know that's enough) to see if there's any sign of a drip. If it's just a small leak, it'll tend to evaporate from engine heat rather than make a spot on the ground.

dieselfan1 · September 7, 2019

3 hours ago, Doublebase said:

So no one’s coolant has dropped at all from that full cool line? Not a bit?

No. None.

It is either leaking or you got a bad head gasket.

If you've had to add like a half gallon I'm betting on the head gasket.

Doublebase · September 8, 2019

4 hours ago, dieselfan1 said:

No. None.

It is either leaking or you got a bad head gasket.

If you've had to add like a half gallon I'm betting on the head gasket.

Normally I'd agree, but it was only like a half an inch from the "full cool" line...didn't seem to drop from that point at all. It takes about a 1/4 of a gallon to fill from the 1/2 inch bellow the cold fill mark. The reservoir is pretty big. I'll keep an eye on it.

Eddie 70 · September 8, 2019

I've been through this. I noticed my coolant down like you did. I went and bought a gallon of demineralized water and topped off the system. Sometime later I am changing the oil and I notice it is down again. Now I know it is going somewhere. I top it off again. it is winter and cool outside. I always back into my parking spot at work. As I am backing in I notice a faint steam coming out from under the hood. There is a hairline crack in the radiator. Luckily for me, I had an extended warranty and it was replaced under that.

I think you can rent a pressure tester from Autozone and see if you have the same thing.

Doublebase · September 8, 2019

12 hours ago, Eddie 70 said:

I've been through this. I noticed my coolant down like you did. I went and bought a gallon of demineralized water and topped off the system. Sometime later I am changing the oil and I notice it is down again. Now I know it is going somewhere. I top it off again. it is winter and cool outside. I always back into my parking spot at work. As I am backing in I notice a faint steam coming out from under the hood. There is a hairline crack in the radiator. Luckily for me, I had an extended warranty and it was replaced under that.

I think you can rent a pressure tester from Autozone and see if you have the same thing.

How many miles?

I'll keep an eye on it, I have a pressure tester.

Eddie 70 · September 8, 2019

37 minutes ago, Doublebase said:

How many miles?

I'll keep an eye on it, I have a pressure tester.

Seems like I was nearing the end of my extended warranty. I was around 95k miles or so.

My wife had a Hummer H3 and I built a homemade pressure tester so I could check the coolant system on the H3. Her radiator developed about a 5 inch crack along the top edge. Seems like my truck did the same. I also used the same tester to check my Z06. It had a bad water pump gasket.

Doublebase · September 21, 2019

It's been two weeks and around 1,200 miles since i topped off my coolant, checked it this morning and it's right where it's supposed to be. So I haven't lost anything.

On a related note, the place where I work has serviced 6 of these trucks in that time span...I went over and checked the coolant levels on all of them...every single one of them was a half inch to an inch bellow the full line...with one bone dry (that one had a small leak on the radiator). The others were fine.

Two of the six trucks had leaking AC condensers. All of them where in for regular service (oil changes 6,000 miles). One truck was over 7,000 miles into their interval and there was no oil on the dipstick...all of the others were at least a half quart, to a quart low. Mileages on the trucks ranged from 29,000 miles to 75,000 miles. For the most part these trucks are pretty reliable - I'd say the biggest thing I'm noticing is AC condensers and oil consumption.