Losing Coolant

[RoGuE]

My dad told me the Low Coolant message came on in his 2002 Suburban yesterday, so I took a look and it looked a little low low, so I put in about a quart of clean water to shut the message off (I'm getting ready to do a coolant replacement). I took a look at it again today after he used it, and its right back down to where it was before I put the water in.

I cannot find any leak anywhere. The water pump is dry, no leaks in the hoses, and the oil looks fine. Any ideas? I kind of want to figure this out before I change the coolant.

 

[Spector]

outside overnight temps have a bearing on my level and it sounds like you checked it hot which is really unpredictable, depends how long driven outside temps etc. Overnight cold is the best IMO but that will also vary by outside temps on one of my cars.

Perhaps a more consistent measurement process to see if really being leaked/burned off or even a UOA looking for coolant

 

[RoGuE]

Each time I checked it, it was about 5 hours after the car was turned off.

 

[Qwiky]

There is about 3 places that it can be going.

1) Leaking somewhere.
2) In the oil.
3) Evaporating.

The amount you are losing may rule out 3).

The oil is easy to check 2).

Check that it is not from expansion and contraction, which I see you already seem to confirm.

If it is a leak it should be easy to find. Could be a pin hole leak or loose clamp that only leaks when it gets real hot, that is enough pressure to exploit the leak.

 

[dwendt44]

Check for leaks immediately after shut down, so they don't dry up on you. BTDT.
I'd check before you shut car off first, as there could be a leak that's only seen when running.

Look engine over carefully; if the leak is toward the middle of the 'V', or close to the rear of engine, it would be hard to see.

My 2¢

 

[mechtech2]

You may simply be filling it up. The reservoir method may take a few fills and drive cycles to do this.
Some evaporation is normal. A long time can result in low levels, esp if the mixture was not correct.
If it will not stabilize, check further. A common pressure test can help.

 

[RoGuE]

I was thinking that too. Would it hurt it to keep adding water to it? I plan on replacing it all and flushing it within the next couple weeks anyway.

 

[dwendt44]

OK to add water. It will just weaken the anti-freeze some; not a problem in GA.
Some engines are designed(?) so that an air bubble is trapped in the head or intake manifold until the engine has been run a few heat cycles as mechtech2 said.

 

[mechtech2]

Water is OK until you figure it out.
But you may weaken the coolant's boiling point , freeze point, and corrosion protection.
No problem in the short term.
If the heads, gaskets,WP, heater core, and lines are OK,
you can drain and refill after your inexpensive water test.

 

[Norse]

Does this have the 5.3 V8? How many miles?

 

[RoGuE]

Yeah, it has the 5.3. It has 114k miles on it. I added one more quart of water on Tuesday night and it seems to have stabilized. So I am going to go ahead and change it all out next week.

 

[mechtech2]

If it is stable, good. they can take a while to stabilize.
This time measure what comes out.

 

[Norse]

Look real close at the underside of the water pump. You will most likely see on the right side lines of dried coolant. The problem is the pump gaskets. Get a set of Fel-Pro gaskets put them on and your leak will be gone.

 

[mechtech2]

It may simply have been more low than you thought.
Evaporation may be the only cause of the low level.
Se if she stabilizes with more coolant in there.

There may of course be a leak, but who knows at this point?

 

[Norse]

Look real close at the underside of the water pump you will know then.