antifreeze question

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

George - 09 Jun 2007 18:50 GMT

Backstory: '99 Cavalier 2.2. Coolant was low. Then, very low.
Thinking it had a leak, and needing to drive it, I added straight water.
I drove it like that for a couple of weeks like that, and the water
level in the surge tank stayed the same. (So, there's still a question
as to why the coolant was low in the first place.) But, for now, my
question is ...

I drained the coolant (radiator & block), and got most of it out. I put
in an appropriate mix of A/F and water. And, after driving it, the
coolant level in the surge tank is down: I had it about 2/3 full; now,
it's maybe 20% or less. I think I've seen this before. I've read that
A/F expands when it gets hot. Is that true? And, if so, how high
should the cold level be in the surge tank?

(Note: I don't see a fill line on the tank, and I don't see any spec in
the Chevy service manual. Of course, sometimes I miss things that are
right in front of me.)

Thanks,
George

Reply to this Message

Comboverfish - 09 Jun 2007 21:49 GMT

> Backstory: '99 Cavalier 2.2. Coolant was low. Then, very low.
> Thinking it had a leak, and needing to drive it, I added straight water.
[quoted text clipped - 16 lines]
> Thanks,
> George

Coolant flow is restricted greatly until the thermostat opens up.
Until this happens, trapped air in the cooling passages can't easily
make its way to the top of the system, then out to atmosphere. It
takes patience during the bleeding process --or-- multiple top-offs to
stabilize the level of coolant in your overflow/pressure tank.
Recommended cold level is about 1/3 full on many bottles. It wouldn't
hurt to go nearer 1/2 full in anticipation of this slow bleeding
process.

It would be wise to diligently keep your system topped off even if you
are planning to find/repair your potential leak. Superheated air
(voids) in the system can damage deck surfaces and gaskets, causing
very expensive repairs.

Toyota MDT in MO

Reply to this Message

Hal - 09 Jun 2007 23:19 GMT

> I drained the coolant (radiator & block), and got most of it out. I put
> in an appropriate mix of A/F and water. And, after driving it, the
> coolant level in the surge tank is down: I had it about 2/3 full; now,
> it's maybe 20% or less. I think I've seen this before. I've read that
> A/F expands when it gets hot. Is that true? And, if so, how high
> should the cold level be in the surge tank?

What most likely happened is you had an air pocket in the block, and
when the thermostat opened the 'bubble' worked its way to the top of
the system(as it should). The air will compress and go past the
radiator cap, and bubble out into the overflow tank.

When things cool off a bit the cooling system will draw coolant back
into the radiator from the overflow, and the level in the overflow
will drop.

I don't think you have a problem right now, just top off the overflow
tank to about halfway full and keep an eye on it. Check it every day
for the next couple days and see if you are still losing any.

Generally speaking when you change the coolant you should fill the
radiator, and while doing so squeeze the upper and lower hoses until
you get all of the air out. Then you start the engine and let it run
with the heater on for a few minutes until the temp gauge comes off
the cold peg, and then you fill it up AGAIN if it has dropped any. The
reason you have to turn on the heater is some vehicles do not
circulate coolant through the heater core unless the heater is on, and
the idea is to get ALL of the air out of the system at once. So you
turn the heat on. ;)

Then after you do all of that you put the cap on and top off the
overflow tank.

Good luck with it.

Chris

Reply to this Message