raccoonjoe

08 HHR SS, roughly 140,000 miles.

I bought this car for the missus earlier this year, have put about 15k miles on it so far. Its been running pretty well for us, with a major annoyance of the cooling fan failure, leading to us needing to be careful about driving in town so it doesn't overheat.

Last week, she calls me from work and tells me the car is making a new noise. After some investigation, I've nailed it down.

Rattle appears when motor is running, idling with no load. It's very quiet and constant. Under load, it becomes much more pronounced. Under higher rpm, the rattle disappears.

When I was driving it and listening, my first thought was a belt tensioner or cat/turbo heat shield. With the hood open, it sounds like it's coming from the valve cover, between cylinders 2 and 3.

When driving through town, it sounds kind of like a quiet moped. With the hood up, it honestly sounds more a first gen VW (or Mercedes) diesel.

firemangeorge

If you have it narrowed down to under the valve cover, I would suggest the next step is to pull the cover and have a look-see.

If you're not positive that's where the noise is, then you should get a mechanics stethoscope and try to pin down the location.
From your description, it's sounds like it's not in the area of the timing chain and components.

An internet guess at this point would be just that. A guess.

raccoonjoe

I appreciate the honesty. My research here has led to mostly cracked blocks, heads, coolant loss, etc, and I can't believe that that is the problem

Any idea what I should be looking for when I get it opened up? Can the valves be adjusted? Is there a possibility of a collapsed lifter?

Thanks again

donbrew

flex pipe.

Did you entertain repairing the fan, or at least finding out what the failure is?

XtremeSS

Fwiw, these engines are direct injection which means it has a secondary high pressure fuel pump which is operated by the cams. When they start to fail, they make more noise than normal. Also, the spring retainers for the valves have been known to come off/break if engine has been reved to high too many times, although this would cause a CEL.

Can you post a video of the sound?

raccoonjoe

The fan is trashed, either the motor or the variable speed controller. New fan is going on order this weekend. Had some.......financial issues to attend to first.

By flex pipe, you mean in the exhaust, running to the cat, correct? That would mean I'm heading the cylinders fire.....doesn't sound quite right for that, but I suppose it could be.

I'll try to get a video up this evening.

db/sb

That's somewhat what ours sounded like when the flex pipe cracked.

donbrew

Okay don't. But you owe me when you get around to checking the most obvious.