MY 2008 HHR has developed an intermittent knock within moments of startup. I have taken the car to two different dealers, left it for days and was told that they cannot duplicate the noise. One dealer service manager heard it, but, only once. I have talked with every one I meet who owns one and no one has heard of the problem. The automatic transmission has been replaced (due to a shifting problem) as well as the starter. Problem remains. I tried recording the noise with a small tape recorder with limited success and am in the process of trying to convince the local dealer (from whom I purchased the vehicle) to take the time to listen to the tape, though the audio results are marginal. Is there any other source of help I am not aware of?

 

While I am not a GM tech, my job involves repairing machinery and electrics.

An intermittent problem is the worst thing to diagnose. While I can appreciate you effort to record the noise, a recording isn't as helpful as you might think as it does not allow the mechanic to determine exactly where the noise is coming from.

I would just keep bringing the car in (Yes, a PITA, but the dealer does not have unlimited bay space to store your car until it makes the noise)

Make a written log of when the noise occurs- how long the car has been sitting, ambient temperature, how long it was running before it was shut off, etc. Be as detailed as possible. Once you determine a pattern of when the noise occurs, you are more likely to be able to get it to do it at the dealer.

Please don't blame the dealer if he is honestly trying to help, but a 'shotgun' approach to repair where you keep swapping out parts hoping to cure the problem seldom works, and only makes both parties angry.


To be honest, if it can't be found, your best bet may be to quietly trade it in.

 

Can you say the this knock happens only after it has been sitting for a few days? Could be the oil has drained down...... this can produce a "rattle" sound more than a hard knock.

 

No, it is a hard knock that happens sporadically and the amount of time it has been sitting parked seems to have nothing to do with it. I sometimes hear it, or one like it when I put the transmission in Drive from Park.

 

Unfortunately, there is no pattern to it. It is totally sporadic. It has happened when the car was parked only five minutes and not again the rest of the day. On the other hand I may go almost a day without hearing it. Some days I will only hear it once in about nine or ten starts throughout the day. Other times I can hear it every other start throughout part of the day.

 

Is it an auto? May want to chec k tq converter

 

It is an automatic tranny. I have been told that the torque converter is a integral part of the transmission and it was replaced at around 11K (for an entirely separate problem). However, the knock was there prior to the swap out and it still exists.

 

Yes, but did they replace it? Get them to produce repair records. You really need to know Exactly what they have done. The torque converter can be separated from the tranny, it is basically the clutch.

 

I hate to say it but things like this you just have to sometimes let them get worse to find them.

It could be anything from a flex plate to cold piston slap to a rod. I may not get worse and it may start to do it all the time.

Like they said document what is going on and see what develpes.

This kind of deal is like finding a hit and miss short in a electrical system. Hard to fix when it is working right.