By on November 21, 2012

TTAC Commentator Tankinbeans writes:

Hello Sanjeev –

I have a goofy problem that I’ve run into my mom’s car. She currently drives a 2005 Sunfire, 2.2 auto, and it has developed an irritating tick. When running, the car sounds like a ticking time-bomb; it’s similar to the sound that might occur when you put a playing card in the spokes of a bicycle tyre.

From what I gather it’s related to the ventilation system because if you turn the airflow selector to foot only, all the way to the left, the noise stops. However, when the selector is on defrost the noise is there. This happens if the fan is off and if the fan is on. With the car running I can hear it outside the car clearly, but it’s more clear near the passenger side windshield wiper. If I place my hand at the base of the windshield I can feel the vibration from whatever is causing it.

We didn’t really notice this until she had an aftermarket radio installed. I don’t think this has anything to do with it, but figured more information is better.


Sanjeev Answers:

Who is this Sanjeev guy and WTF is up with him getting into my business?  Seriously, since I was a little kid, this has been my second name. I blame my parents for NOT giving me this fantastic name to start. But I digress…

I can’t find a correlation between your stereo and the ticking noise, unless the stereo installer had a REAL hard time getting the aftermarket bits in without mucking up with the HVAC control unit and the big box o’ crap (blower motor, evaporator, heater core, blend door, etc) behind the dash. And anything is possible, for sure. Just for giggles, disconnect the stereo’s new wiring harness from the Sunfire’s factory wiring and see what happens. If the noise goes away, you got a big problem with the installer.

If the stereo isn’t at fault, there has to be something wrong with the blend door system in the HVAC box behind the dash. But that makes no sense, since the noise is independent of the fan’s (i.e. blower motor) operation. Dammit: SANJEEV FAIL.

Perhaps there’s a relay for the blower motor that’s connected to the stereo’s wiring…nah, SANJEEV FAIL.

Have you considered the possibility of badge engineering being at the heart of the problem? Put the stereo in a 2005 Cavalier and see what happens…nope, SANJEEV FAIL.

Sanjeev gives up. Off to you Best and Brightest.

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25 Comments on “Piston Slap: Fix my Sunfire, Sanjeev!...”

  • avatar
    bumpy ii

    Left-field answer: card in the bicycle spokes could be the timing chain tensioner. Run the HVAC fan with the engine off and cycle through the settings to make sure it’s not the engine. If it’s not, take the blower fan out and clean out all the crap that fell in from the outside vents.Get a hose and a big air compressor and blow air in through the appropriate interior vents as you cycle the controls.

    • 0 avatar

      I was thinking the adhesive-backed foam carmakers love putting around every joint in the air system to insulate from air leaks. It rots after a few years of heat cycles in the dash, and if a piece partially breaks loose it could just be flapping in the airflow. The stuff progressively deteriorated and flew out of the vents in my ’96 Galant. But only after I disassembled the dash components a few times to fix broke trim pieces, hook up a factory trunk-mounted CD changer, and replace burnt out lightbulbs. If the installer even jarred part of the air system, it could have just knocked one end of a piece loose.

  • avatar

    If it’s not fan speed related, but is affected by the mode settings, it’s likely caused by the air inlet door actuator. The gear on the motor has likely failed.

    Most cars nowadays use all electric actuators to move all of the HVAC box doors, but in the last of the J-bodys I think there is only 1 maybe 2 actuators in the entire case as I’m fairly sure the blend control is manual.

    Either way, the dash has to come apart and the HVAC box at least partially removed to change it.

    • 0 avatar

      I was going to suggest the same thing. I have a late 90s Volvo which has electric motors to actuate various parts of the HVAC system, as you suggest. The passenger side temperature blend motor has something messed up, and when the car gets close to the selected temperature it starts to tick and tap and go on. If I choose a new temp far enough away from the previous setting it will stop until the car gets to that temp, and then I move it again. I need to replace the motor to fix it but it’s expensive (~$250 I think) and I have to take it to the dealer to be programmed (more $$) so I’ll probably leave it.

  • avatar

    Get yourself 3 feet of heater hose or similar tubing. (3/4 to 1 inch inside diameter)

    Hold one end of the tubing to your ear and feed the other end around with your other hand. Start working everywhere around the car.

    I would start underhood around the engine, then under the dash. Be safe with your hand around all the engine’s moving parts. (If you are a lawyer, print that on your piece of heater hose) If you are still having problems finding the source you may even need to jack the car up and check the exhaust system and transmission.

    This hose is a great tool to locate the source of mechanical noise. The mechanic stethoscopes can be used to narrow it closer after you have found the location of the noise.

    To check the electrical system. Remove one fuse or relay at a time and see if the noise quits. That will help you isolate what circuit has the issue.

  • avatar

    Just a note about the picture.. good lord could someone have found a more fugly hood for that car?

    • 0 avatar

      LOL. “How to make a Sunfire sedan even uglier, step 1.”

      The air intakes are a bit much (okay, they’re ridiculous), but I actually don’t mind what they did with the trailing edges of the headlights. Makes the car look positively evil from the front. That element alone wouldn’t hurt the styling. Which is still 90s-bulbous in every other way.

      • 0 avatar

        They did a fantastic job with the headlights. Not that the factory lights were ugly…

      • 0 avatar

        I’m wondering what they would look like on a later model upper trim with the more aggressive front bumper and fog lights. Or even on the 2-door GXP concept Pontiac showed circa 2003. Wouldn’t look bad at all.

        Aside: That led my wandering mind to think of getting a base 4-door with wheelcovers and crank windows and popping in the 2.0L turbo Ecotec from a late ‘aughts GM Delta car (Cobalt or HHR SS, or even a Regal Turbo). Hmmmm… Sleeper-city.

      • 0 avatar

        Lights are more like an FTO now.

    • 0 avatar

      That wound seems to be self inflicted rather than purchased as it appears to be a rather clumsy take on the ram-air hood of its big brother. Then again it might just be a product from the fine makers of combat body kits?

  • avatar
    doctor olds

    The radio shop may have disturbed the routing of something so that it comes into contact with the blower fan. If it is, blower speed should change the frequency of the noise.

    A friend suddenly had an irritating, faint ticking noise in his Tracker. Careful investigation disclosed that a long pine needle had fallen into the hvac air intake and touched componenets under the hood such that it actually transmittd underhood noise into the passenger compartment.

    Noises that suddenly appear after a repair are typically the result of something related to the work that was done, perhaps as simple as a hose or wiring harness touching something it is not supposed to.

  • avatar

    Had a similar issue on my 96 Intrepid. It was the fresh air door. Luckily, I didn’t have to pull the whole dash out and was able to flip the gear over and never had an issue with it again. This being a Pontiac, I am not sure what their actuator is like or how it is put together.

    You say you can bypass it by moving the selector all the way to the left (foot only). It’s also possible an actuator arm has fallen off and will not allow the gear/door to hit its limit switch. Pull the glove and see if you can trace any moving parts. Start diggin’..

  • avatar

    It’s fall; I’ve had the problem of leaves getting into the blower motor area and they are noisy when the blower fan is spinning.

  • avatar

    I suspect the temperature blend-door actuator or perhaps the mode actuator. It’s stuck at some point in its travel and the gear popping is the resultant noise.

    • 0 avatar

      Either that or one of the plastic gears has cracked and no longer grips the shaft that it is pressed onto – resulting in the drive motor never turning off because it can’t get the blend door into the proper position.

      Get online and check the forums – I’m active in some GM forums and blend door actuator motor problems are very common across multiple GM brands (as they tended to use the same components).

  • avatar

    Our Cavalier had a similar noise from the fan blower and the ticking noise would change with speeds. Turns out some leaves got into the fan from the outside and the stems were stuck in the fan blades. Taking the blower assembly out and cleaning it fixed the ‘tick’.

  • avatar
    el scotto

    Uh, how do the leaves get into the blower motor? Shouldn’t there be some sort of screen somewhere in the system? I bow to those with more knowledge on this question.

  • avatar
    Rick S

    My guess would be A/C compressor. I’ve had them make some pretty strange noises as the bearings wear down, and because defrost setting = compressor always engaged it could be an option. Try opening the hood and having someone click the A/C button on and off while the fan is blowing. Watch the pulley and see if there is any correlation between sound and use of the compressor. Just a random shot, but good luck!

  • avatar

    There a yellow 2004 Sunfire with many parts to pick from in Murlee’s favorite bone yard! Can fix in a jiffy!

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