Engine Knocking & Low Oil Pressure

Start at the beginning. You said you recently had an oil change and the noise got WORSE after that............................ Its possible that whoever changed your oil SIMPLY used an oil that is thinner than what your engine NOW needs to prevent the knocking, AND/OR may not have put in enough oil, AND/OR did not tigten the oil filter and drain plug(s) enough to NOW have an adequate quantity of the right viscosity oil to prevent knocking....................................... I'm going to assume that you have checked the oil dipstick to be sure you have enough oil in the engine, AND have checked for any significant oil leaks from the engine.........................If you HAVE DONE THESE, and there IS enough oil YOU MUST STOP DRIVING THE CAR UNTIL YOU INCREASE EITHER THE OIL PRESSURE, increase the OIL FLOW or IMMEDIATELY PUT IN AN OIL THAT IS HIGHER VISCOSITY-or EXPENSIVE-TO-FIX EBGINE DAMAGE WILL KEEP PROGRESSING. ........................................................................................................... LOW oil pressure VERY OFTEN will increase with a slight increase in the speed of the engine, so its not uncommon for an engine with a SLIGHT knock at idle, to have the noise go away as soon as the engine speeds up a little........................................................... The EASIEST/CHEAPEST way to check how bad the problem is to turn up the curb idle, drain some (or all) of your oil and put in enough oil to reach the proper level. Operating an engine with too loow oil pressure (OR insufficient oil volume flow, or both) bad enough toproduce a steady engine knock, produces IRREVERSIBLE WEAR....................................... Low oil pressure will definitely cause an engine knock-once the pressure gets low enough to NOT provide a thick enough film of oil between the parts most liable to be producing the knocking noises. So would having a LOOSE OIL PUMP that is not able to pull a CONTINUOUS, steady flow of oil through itself................................................................................ The earliest noise-producing parts are usually the ROD LOWER BEARINGS, the ROD WRIST PIN BEARINGS and the MAIN (crankshaft) BEARINGS.....ALL of these parts are quite expensive to replace becaUSE THERE'S A LOT OF LABOR INVOLVED, but a lot of other parts will be also wearing faster than normal............................... ............... Upping the idlle NOW and changing to a thicker oil, such as 10w40 or 20W50 instead of 5W30 or 10W30, may very well be all that is needed to reduce or eliminate the constant engine knock..................................If doing that does NOT help, have someone test your oil pressure with a mechanical gauge before panicking.

Start at the beginning. You said the noise GOT WORSE after a recent oil change. Its possible whoever changed the oil didn't use enough, OR used oil that is the wrong viscosity. Or that your engine has enough miles on it that the clearances have opened up enough that you need a HIGHER THAN ORIGINALLY SPECIFIED oil (such as 20W50 instead 10W30) to fill up those increased clearances enough to keep parts from touching that are supposed to be being held apart by the film of oil. 1 Check the oil level-with the engine cold. 2. if the oil is low, check for evidence of leakage, especially around the oil filter and the oil drain plug(s). Sometimes the filter or drain plugs are not tightened enough after draining the oil or OVERTIGHTENED, so that the threads are stripped on the oil pan or plug, creating a path for oil to leak out................................. 3. If 1 & 2 check out, the cheapest/easiest way to check if its a MINOR issue, is to have someone check your oil pressure at idle and at a higher speed (using a mechanical gauge) If the oil pressure checks out as STEADY but low, BOTH at idle and at a higher speeds, odds are fair that thicker oil MAY still help.(If you keep driving with a knock the wear gets worse) IF THE OIL PRESSURE READINGS FLUCTUATE when tested, the oil pump or its pickup arm may be loose, or the oil screen on the pickup arm may be partly blocked by accumulated, possibly floating crud, OR the oil pressure relief valve (In Fords its often in the base where the oil filter screws in) may be sticking. IN ANY CASE, drain the oil that is in the crankcase NOW and check for crud in it and also scrape the inside bottom of the oil pan with a wire and see if it comes out with any crud stuck to the wire. iF THERE IS CRUD, THE LOGICAL THING TO DO IS TO PULL THE OIL PAN TO CLEAN IT AND THE PUMPS PICKUP ARM AND SCREEN. [btw, IF 'THE MECHANIC' DID NOT ALREADY CHECK OR SUGGEST CHECKING YOUR OIL PRESSURE AFTER YOU TOLD HIM ABOUT THE KNOCKING YOU MIGHT WANT TO START LOOK NG FOR A DIFFERENT MECHANIC.}