Q: Knocking from engine.

asked by on January 12, 2016

My jeep's engine is knocking.

Unfortunately without more information it will be difficult to narrow down why you are experiencing a knocking sound in your vehicle. In my experience Envoys have had many different reasons that could duplicate an engine knock. The most common is oil starvation. If engine oil is unable to travel through the oil passages to lubricate (this may be due to lack of oil or oil pump failure), metal to metal contact will occur on moving parts. At any time you hear an engine knock coming from your car, turn the vehicle off immediately and check the engine oil. Engine oil is probably the most common reason for the engine knock, especially in higher mileage engines.

Older engines with higher mileage tend to burn and/or leak oil between oil changes. When this happens the crankshaft bearings are usually the first to make noise. When you reach this point, it may be time to rebuild the engine. Rebuilding an engine would be a worst case scenario. If you have sufficient oil on the dipstick and the condition of the oil is good (not black, or contaminated with debris) the problem may lie in the oil pump or elsewhere.

Other possibilities include having bad or noisy bearings on one of the pulleys that drive the accessories. These include the alternator and the A/C compressor. To verify exactly why you are hearing a knocking noise in your GMC, it is best to enlist the assistance of a certified mechanic to inspect and properly diagnose your vehicle so you can get back on the road safely.

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

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

Car squeaking around belt area

The symptoms you describe for your GMC Yukon lead me to believe that we are dealing with a worn out serpentine belt. As the belt ages, the rubber starts to deteriorate and stretch. This causes the belt to rub material...

P0014 on scanner

Hi and thanks for contacting YourMechanic. The code p0014 refers to the camshaft position sensor 'B' circuit with the timing over-advanced. The TPS will not make the computer think of a cam not adjusting correctly. With the code p0014, check...

Car won't charge

Hello! Since you have replaced the battery, we will put that to the side, but we cannot ignore it. A failed charging system puts a large load on a battery and can damage a new one, so I suggest having...

Related articles

What is Rear-Wheel Drive?
For For the better part of the twentieth century, nearly every vehicle on the road had the engine sending power to the rear wheels. This arrangement makes a lot of sense to designers, with the rear wheels handling all of...
What Is Engine Displacement?
Engine displacement is the swept volume of pistons inside the cylinders. Displacement has an impact on increasing car power or fuel efficiency.
A Buyer’s Guide to the 2012 GMC Sierra
The The 2012 GMC Sierra may not have sold quite as well as the Ford F-150, but that doesn’t mean you should dismiss this rugged and reliable model. For one thing, the Sierra is available in a half-ton version (1500)...