Q: Engine making weird noises and revving

asked by on

When I start up the car, the engine revs up and makes this weird sound. It mostly does it when it is cold outside and not all of the time. The dealership has looked at it three times and can't find the problem. The vehicle also recently issued a loud shriek with the Engine light coming on. The AC has been acting up as well, with it coming out very low and high before eventually kicking in.

With these combination of symptoms, it sounds like your car has a drive belt problem. When it is cold outside, there is more load on the belt on initial startup. In other words, the pulleys are harder to turn. When this happens, the power steering fluid is usually thick, the alternator is charging a slightly drained battery, and the AC compressor oil gets thick, too. The Check Engine Light might be a coincidence, but it may also help find the problem. The code will be stored even if the light is off now. The issue you mentioned with the AC is a strong clue as well. If the clutch is weak it may slip and make noise at first. When your heater controls are in the defroster position, or floor and defroster, this automatically commands the AC compressor to dehumidify the air. If the noise happens every cold morning, try leaving your heater totally off and see if the noise stops. If it does, then this could be one explanation for the noise. The belt itself could also be slipping - indicating a worn belt or tensioner. I would think that the dealer would probably have spotted this though. One more possibility is that the harmonic balancer has failed. The pulley that drives the accessories is connected to the crankshaft through a piece of rubber that’s bonded to each piece. The bond can break and it will intermittently slip, usually under heavy load or when it is raining. A qualified mechanic, such as one from YourMechanic, can come and inspect the related parts to determine what is causing your car’s strange noises.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Engine making weird noises and revving

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How do turn off the 'horn beep' function on a mopar aftermarket remote start in a 2015 Jeep Grand Cherokee?

If you do not have the publications and manual that came with the system, you may inquire about them at the dealer or look it up online so you have the manual for the system. If this is not a...

Q: A/C makes loud humming sound

The blower fan motor has something caught in it or the air filter is not in position and hitting the blower fan. Have the person or shop that did the work fix it. The filter may be out of position...

Q: Hi, my name is Jorge from North Houston, TX, and I'd like to know the location of the Expansion Valve (Orifice Tube) for 2011 GMC

Your vehicle has an expansion valve mounted at the firewall behind the two a/c lines where they connect to the evaporator assembly. You will need to evacuate the a/c refrigerant and remove line connection and then unbolt the expansion valve....

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...