Engine knocks when startup but disappears after engine warms up.....could the oil pump be defective.......what about the knock sensor....

could it be a high pitch knocking like a ticking-this would be a lifter thats not pumping up right any-it may be time for oil change to winter oil-5w20-oil change could help anyway-cheers Denny

sounds like a crushed valve lifter

engine knocking sound like worn engine bearings or low oil level. if oil level okay more likely oil pump has failed or engine bearings worn out or engine oil diluted with antifreeze or gasoline causing viscosity oil to be too thin.if oil and filter been changed.if you see check engine light flashing code scan for faulty knock sensor. if you see low oil light flashing engine knocking damaged to engine done.

did the oil light come on? it it did that means a low pressure situation which can cause con rod bearing damage. the knock sensor can cause that too.

Hi welcom to fixya. A defective knock sensor may cause engine detonation or reduced spark advance and fuel economy. When a knock sensor is removed and replaced, the sensor must be tightened to its specified torque. If the knock sensor is installed tighter than it should be, it may become too sensitive and provide an excessively high voltage signal, resulting in more spark ****** than required. When the knock sensor is installed looser than it should be, the knock sensor signal will be lower than normal, resulting in engine detonation.
To replace the knock sensor:

• Disconnect the knock sensor wiring connector.
• Then, unscrew the sensor.
• Remove the knock sensor.
• Reverse the procedures to install the part.
• 15 ft.lbs.torque
• hope this helps.Thank You for using fixya..iluv2fish.. Ray..

You have either worn out connecting rod bearings or a weak oil pump it is possible the oil pump pick up screen is clogged.

knocks when cold ( Start ), then sort of diminish or disappears when warming up ???

Knocking goes faster when accelerating when cold ???

If Yes, then Piston knocking on the wall of the cylinder . The sound disappears as the engine is getting warmer it dilates and the gap gets smaller.

If this just started,

1. Put quality oil & filter ( Mobile Full Synthetic Oil & Mobile Oil Filter or Purolator )

2. Do not put cleaning agents mixed with oil.

3. Personaly i've put "Restore" Engine Restorer & Lubricant in cars with more then 200 000 km and the results are amazing. But only "Restore". My Volvo is at close to 300 000 km, and it runs great. It's not a cleaning agent.

By experience if the knocking just started you can put an easy extra 100 000 km on the engine before a rebuilt. Quality Oil & let the engine warm up ( 3 mins ).

sound like an internal engine problem. either one or more of the pistons has "piston slap" and that knocking will diminish as the engine warms up or possibly a rod bearing is worn out. have a tech do a manual oil pressure test to make sure the oil pump and main bearings are ok. piston slap or knock that decreases when the engine warms up is not that serious, but a rod bearing knock or possible oil pump failure should be taken care of asap.

probably the oil pump

oil pump is in the oil pan and if you have no or low oil pressure replace pump before doing anything with knock sensor. knock sensor is more or less a microphone and listens for spark knock but will set codes for any knocking or tapping noise which is commonly heard if oil pump is malfunctioning