OK... this goes against every thing I know.

I have a coolant leak, its on the drivers side.
The ONLY time I notice it has been over the VERY COLD nights here lately.
Last night it was about 10 or 12 degrees Farenheit
Same goes for the night before about 15 degrees.

It does not leak when engine is up to teperature and sitting at idle
Nor does it leak when parked at work all day after coming to temperature on the way to work.
It only leaks overnight.

It leaks about a .10 of a Litre

Is it possible that the temperature changes has caused something to shrink just enough
to allow coolant to escape??

Or does the coolant go against all logic and actually become more viscous.... as the temperature goes down..
thereby allowing it to seep out of some tiny crack that it usualy doesnt??

 

Make sure you keep your coolant system completely full and get it into a shop for a coolant pressure test ASAP. Don't waste time for us to guess.

 

I think you mean less viscous. So you actually see coolant somewhere, where? There isn't much on the driver's side other than the throttle body heater which tend to leak pretty often, start by tightening up the hose connections there.

 

I could see a small puddle under the driver side front of the engine bay...
First I thought it was a transmission cooler line, because it had some fluid on it,
but upon dabbing the spot on the ground with a paper towel....
Coolant..

Thanks for the input..
Ill check it out..

I was wondering where it could be coming from as well.... thought maybe the bottom of the radiator..

I recently flushed the system, and then purged it but havnt unsealed the system since..
I did open the system up while coolant was still warm today to top it off, (about .5 litre) and released alot of air pressure..
possibly the last of the purge.. we will see if there if fluid on the ground tomorrow...

 

When you flushed your coolant did you add a 50/50 premied coolant AND distilled water?
Or just the 50/50 premixed coolant?

Yes things can shrink at different rates, your freeze plugs could be rusted and be leaking.
Water pump bearing could be bad, doubt it with your miles though.

 

Nope bought 100 percent coolant.. Cut it with Distilled Water
Down to 50/50

 

I'd check the upper hose connection at the radiator, other than that it would have to be the radiator itself I guess. I just fixed a leaky hose connection at the reservoir that seems to have just started with thiscold snap here. Yeah stuff contracts at different rates and gets very stiff when cold and probably doesn't seal well. If you end up pressure checking it, I've seen a kit you can buy that lets you do it yourself. I'd sure like to know how well they work.

 

Did you replace your radiator hoses resently?
If so maybe a hose clamp is loose, if not then maybe you have a cracked hose.

 

Well odd thing about it,

I hadnt messed with anything over there at all, I did the lower radiator hose (passenger side)
and the thermostat (center).. anyhow yesterday when I opened the system while it was still kind of warm
It let out considerable pressure.. Topped it up and did nothing else.

This morning.. no spot under the truck, of course it wasnt very cold last night, but I think the cold and the pressure that was in they system was just enough to force past some clamp over there somewhere..

The first time I burped it this exact thing happened with the lower radiator hose..

Odd... I am not going to pressure test it..

 

I would just keep a eye on it.
I have a small leak too, it is my thermostat housing, it has a small nick in it and every once in a blue moon it will drip coolant on top of the engine.
I am going to replace it this summer, but it has been that way ever since I bought the truck almost two years ago.