That has been the M.O. for a while now - couple weeks. Now, there's no heat. I can see my breath 30 minutes into my commute...

I have been filling at the rad cap when needed, and keeping coolant in the reservoir. I have had a stuck-open thermostat for a while, but this no-heat has been MUCH worse than the previous few months.

I have replaced 2 rad caps, and will do the stat soon, but these symptoms seem weird. Is it just an air bubble?

 

If you are loosing coolant and having to add via the road cap, it sounds like you have much more than an air bubble.

Just change the thermostat and burp the system with a fresh load of dexcool. Then.trouble shoot it from the beginning. Feel the heater hoses - is the intake warm? Is the return line warm? Monitor the coolant temp via the digital readout. Is there coolant in the oil? Does the exhaust smell of coolant and have too much visible vapor? Does a code get thrown?

 

Where is the coolant going? An air bubble would eventually fill up.

 

Check the rad cap, for pressure and the oil cap for condensation!

 

I have no signs of oil/coolant mixing.

I think I might have figured it out today. Some Dexcool pessimist (supplier engineer) was asking me about the intake manifold gasket (where the GM 3.1 and 3.4 had their issues). That very may well be what the explanation is. I'm getting it looked at Thursday, and will suggest it to them.

I have had only the P0128 from a crappy O'Reilly's t-stat for a while, but this is new. I'll have the shop fix the t-stat too while they are in there. In cold weather, I wouldn't notice a little extra steam or light smoke at all...

Thanks for the sounding board. Dis is da place...

 

No, there is no coolant at any part of the intake manifold. I don't think the '08s had the porous block problem. A few members have had bad filler caps. You should also look at the coolant possibly leaking at the turbo, as well as the oil cooler.

As far as the heater, see if you can blow compressed air through the heater core, it may be plugged up.

 

2008 was the year for porosity in the block n the 2.0 SS LNF


https://www.chevyhhr.net/forums/ss-s...nt-leak-51076/

 

See, I learn something every day! Some days I just have to learn again something I used to know. Can't trust the memory anymore.

So yeah, Blue_SS, look for porous block also. That would be very bad news.

 

ZZP still has LNF short blocks


Ecotec Parts Gen 3 LNF Short Block

And engines

GM Chevrolet-Pontiac-Solstice-Sky Ecotec LNF LDK 2.0L Turbo Engine Brand New RWD

Please read all of the product description!

 

A porous block issue would be putting that lost coolant into the oil pan.
Blue_SS said his oil is OK. Based on the oil being OK, then I doubt it's a block problem.
I would look elsewhere for a leak as others have stated.