What would cause a knocking sound after replacing the spark plugs in 2002 F-150?

Answer 1

Usually, if this sound is of very short duration it is because you replaced the filter. The oil filter on your engine has incorporated an anti-drainback valve which, once removed, removes oil from your engine passages that usually remain filled with oil. Upon starting the engine, it may take several seconds for oil pressure to reach normal levels and achieve quiet operation.

Note that on most fuel injected GM vehicles, the engine should not start until acceptable oil pressure is achieved and this noise indicates unacceptable quality of oil is being used.

Many modern engines made by European auto makers (notably MB and WV) require very specific properties in engine oil. Be sure that you are using an oil that meets the manufacturer's specifications.

If you have a Hyundai 4-cylinder engine and the noise lasts for more than about 3 to 4 seconds you may have an internal engine problem. If the noise persists for a few days or longer, consult with a mechanic.

== == On many vehicles with hydraulic valve lash adjustment (hydraulic lifters or hydraulic rockers) you should not change the oil with a warm or hot engine. If you do so, avoid any highway driving until the engine cools down to ambient temperature. Noise may indicate that you are damaging the engine's valvetrain.

it could be of an old beat up engine and a cylinder is bad..when that goes bad so does the ring..if you have that, it must be replaced.. a.s.a.p. i t could be a shortage of oil, transmission fluid, no oil, bad oil.. It is not abnormal for an engine to 'rap' for a few seconds on the first start immediately after an oil change; it takes a moment for the fresh oil to make its way to the valvetrain. If the rap is persistent, the above answer holds good suggestions 1. check the Oil Dip stick to see if you have oil in the engine 2. What does the oil pressure guage say your pressure is on he dash 3. did you recently fill up with gas that is junky may be 4. it could be a spun bearing, if so you will have to get it fix How to check if it is a spun bearing very simple dran the oil out of your truck Check the Bolt that you took out of the oil pan and see if there are small metal flaks stuck to it, also look up in the oil pan bolt hole to see if you see large metal pieces there. pretty simple cure in most cases just add oil to the filter before installation make sure the filter it top-ed off this should minimze the knock to less then a second I agree with the previous answer of topping the oil filter. In addition, if the noise is still present, change the filter again, and spray brake clean into the oil filter nipple. I would change the oil again at this point.

Answer 2

You probably have two of the wires mixed up. They are specific to one cylinder.