There is much discussion in the LNF world, Cobalt SS as well as HHR SS, about 2008 “porous blocks” that raise enough concern about the risk that it seems to reduce the value of 2008 cars. The 2.2 blocks used the same “lost foam” casting technology. If have no idea if they were manufactured in the same facility or even suffered the same problem, but it seems plausible. The problem may have nothing to do with lost foam, IDK. With the LNF’s the perception is that the problem limited to 2008, but any casting process can suffer random flaws.

It would seem, once you eliminate other possible causes, that you need to consider that block has a very small leak between an oil and coolant passage.

 

The 2008 2.0 LNF block had the porosity issues, not the 2.2, different blocks in 2008 because of the VVT.
after 15 years of service, I strongly doubt that porosity would be the problem , it would have shown up during the warranty period. This might just be a head gasket, I’ve not seen any reports of a cracked head in any HHRs or Cobalts

 

AND, porosity doesn't mean what you think it means. One of the bolt holes was supposed to be blind but got drilled through, and some rough. On some engines the casting process left bubbles, that turned into voids when machined under the head gasket. It does not mean "cracks in block".

 

Alright, I finally got the water pump installed and ran it today. I noticed that the engine pitch sounded much higher so I'm guessing it's a water pump whine. I think I will have to reset the tensioner for it.
I removed the bolts from the tool holding the sprocket at one point not realizing that you don't need to rotate the tool at all during the installation. The videos on water pump installation really don't like to use the water pump tool for the entirety of the installation.
Are there any videos I can listen to the water pump whine just to match up the sound? I can't find any.

Aside from that issue, it's a little amazing how the ZZP water pump has no plastic at $30 unlike the water pump I got from the Cloyes kit.

 

Sad but true, the water pump holding tool is hit and miss

https://www.chevyhhr.net/forums/how-...et-tool-65613/


And the fix

https://www.chevyhhr.net/forums/prob...nt-woes-58494/

 

Thanks for the info, looks like I'll be taking the timing cover off tomorrow to fix that.
I was looking through ZZP's website and I noticed they have an upgraded timing chain guide here: https://zzperformance.com/products/z...ng-chain-guide
Wondering - is this worth it to replace while I have the cover off? $80 seems like a lot for a guide plus I'm not even sure if this water pump will fix the issue.

 

I would do it. Plan to if/when I have the cover off.

 

Okay, got the timing cover off and reset the balance shaft tensioner. The timing gasket looks fine - is this safe to reuse?
While I'm waiting for a new crankshaft bolt, I might as well buy the ZZP guide. Looks like all I have to do is remove the old guide and install that without touching anything else. I was checking the bolts in the timing chain area and I must've forgotten to torque the lower bolt for that guide too. It was about one turn away from even being hand-tight.

 

You got the upgraded guide bolt too?

 

Yep, installed that about 2 years ago