zayres29 Posted January 31, 2011 Report Share Posted January 31, 2011 i noticed the other day that when i start up my truck (91 c1500 w/350 tbi) that there is a little bit of a knock for just a second when it fires then it goes away but how can i fix this Btw that was the first person. Ever banned by me while dropping a deuce. Feel privileged Link to comment Share on other sites More sharing options...
GoHoMeUcRyBaBy Posted January 31, 2011 Report Share Posted January 31, 2011 Engine knocking refers to the metallic sound an engine can produce when pressure is applied to the gas pedal. The noise may be a hollow knocking sound or more of a rattling sound—in either case, it's not a sound you want to hear. When an engine pings, it releases pollution into the environment in the form of nitrogen oxide (NOx) and raw, unburned hydrocarbons (HCs). These two chemicals are poisonous gases that show up as yellowish-brownish in a polluted sky. They can also cause respiratory problems like asthma and emphysema. Common Reasons for Engine Knocking Improper Combustion Process An engine can ping (or knock) due to an improper combustion process. A "spark knock" is the result of combustion occurring too early. Early combustion can occur from carbon buildup inside the combustion chamber, a lean air/fuel mixture, and advanced ignition timing (spark plug firing too soon). In a properly-firing cylinder, the spark plug ignites the air/fuel mixture and a flame front starts on one side of the piston and burns across the top to the other side, which creates a rapid and evenly-expanding gas that pushes down on the top of the piston. When the air/fuel mixture is ignited prior to the spark plug firing, the two flame fronts collide, causing the pinging/knocking noise. Engine Is Too Hot An engine can ping because it is too hot. This is another uneven combustion scenario that is caused by the air-to-fuel mixture "lighting off" by itself. If the cooling system does not keep the engine's combustion chamber temperature in check, the air-to-fuel mixture will begin to spontaneously explode. This is also called "pre-ignition." Improper Gasoline Octane In addition to cooling system problems, pinging can be caused by improper gasoline octane, an overly lean air-to-fuel mixture, or a lack of proper exhaust gas recirculation. The exhaust gas recirculation system (EGR) was created to neutralize engine pinging by adding a small amount of exhaust gas to the air-to-fuel mixture going in to the combustion process, which limits the peak combustion chamber temperature. Internal Mechanical Problems Internal mechanical problems can also cause engine knocking. One such problem stems from excessive clearance inside the bearings in the connecting rods that transfer the downward movement of the pistons to crankshaft rotation. Each time the piston changes direction, there is a knock from the metal hitting metal. This is often referred to as a "rod knock." It is usually very rhythmic—it increases with engine speed and intensifies with engine load. Other mechanical problems that lead to engine knocking are: * Defective main crankshaft bearings * A cracked or broken flywheel or flex-plate that attaches the engine to the transmission * A worn water pump bearing * A failed or loose timing belt tensioner can knock when the timing belt slaps against it * An air conditioning compressor can knock when it is failing or icing up * An alternator with worn rotor bearings can knock when the pistons fire Be sure to properly inspect and verify the root cause of the knocking sound, as it can be tricky to pinpoint. You don't want to replace the entire engine only to find out that the knocking was coming from a cracked hub on the transmission flywheel or flex-plate. Ouch! 2002 Gmc Sierra 4x4 2 10" dual 2 ohm p3's Custom box (34hz) Kenwood eXcelon 1800 watt amp Kennwood monitor Polk Audio door speakers Kenwood tweeters Boston acoustics rear speakers alpine 4 channel Link to comment Share on other sites More sharing options...
zayres29 Posted January 31, 2011 Author Report Share Posted January 31, 2011 in my case i think its carbon build up / spark plugs are shot / timing / lean but thats just my guess i tried to put new plugs in today but its damn near impossible to get the wires off the plugs and the plugs themselves are seized to the head i need a breaker bar or something Btw that was the first person. Ever banned by me while dropping a deuce. Feel privileged Link to comment Share on other sites More sharing options...
Mikesmith0890 Posted January 31, 2011 Report Share Posted January 31, 2011 Get some Lucas Oil stabilizer. OR, swap out to a thinner oil. The knock you hear on start up is due to the lack of oil in the cylinder until it gets some pulled up and then goes away, otherwise known as a dry start. AlphaDamp Sound Deadening CDL Mat - The best Vibration Damper Ever! I'd hit that so fucking hard whoever pulled me out would be King of England. Lol... looks like we were on the same page. Car-B-Ques suck.ya, tires and paint burning make the marshmallows taste funny. Link to comment Share on other sites More sharing options...
rubbernutz1 Posted January 31, 2011 Report Share Posted January 31, 2011 u cant realy make that problem go away. what ur hearing is the main bearings knocking. theyr doin that cus when u 1st start it up theres no oil on the crank shaft. when the oil pump pumps the oil up in the motor it stops knocking. sorry to tell ya but the only REAL way to make it stop is to replace the main bearings, in other words overhauling the motor. u can try using thicker oil it should help but it still dont do away with the problem. dont worry thow its normal wear and tear all motors eventually start doing it. Link to comment Share on other sites More sharing options...
zayres29 Posted January 31, 2011 Author Report Share Posted January 31, 2011 Get some Lucas Oil stabilizer. OR, swap out to a thinner oil. The knock you hear on start up is due to the lack of oil in the cylinder until it gets some pulled up and then goes away, otherwise known as a dry start. u cant realy make that problem go away. what ur hearing is the main bearings knocking. theyr doin that cus when u 1st start it up theres no oil on the crank shaft. when the oil pump pumps the oil up in the motor it stops knocking. sorry to tell ya but the only REAL way to make it stop is to replace the main bearings, in other words overhauling the motor. u can try using thicker oil it should help but it still dont do away with the problem. dont worry thow its normal wear and tear all motors eventually start doing it. one says thinner oil and the other says thicker oil... i have plans to rebuild the engine in the future but i just want to prevent any major problems Btw that was the first person. Ever banned by me while dropping a deuce. Feel privileged Link to comment Share on other sites More sharing options...
GoHoMeUcRyBaBy Posted January 31, 2011 Report Share Posted January 31, 2011 Get some Lucas Oil stabilizer. OR, swap out to a thinner oil. The knock you hear on start up is due to the lack of oil in the cylinder until it gets some pulled up and then goes away, otherwise known as a dry start. thats exactly what my truck is doing when i start it and then get going. 2002 Gmc Sierra 4x4 2 10" dual 2 ohm p3's Custom box (34hz) Kenwood eXcelon 1800 watt amp Kennwood monitor Polk Audio door speakers Kenwood tweeters Boston acoustics rear speakers alpine 4 channel Link to comment Share on other sites More sharing options...
zayres29 Posted January 31, 2011 Author Report Share Posted January 31, 2011 it goes away almost instantly after it turns over Btw that was the first person. Ever banned by me while dropping a deuce. Feel privileged Link to comment Share on other sites More sharing options...
Mikesmith0890 Posted January 31, 2011 Report Share Posted January 31, 2011 Thicker oil would be appropriate if the motor is knocking continuously while driving/idling. Thinner oil if just on start up to make it easier to draw. If you live in a colder climate, you're supposed to use thinner oil in the winter. If you run 10-30 in the summer, winter you should run 5-30. The lucas oil stablizer also helps. Edited for spelling AlphaDamp Sound Deadening CDL Mat - The best Vibration Damper Ever! I'd hit that so fucking hard whoever pulled me out would be King of England. Lol... looks like we were on the same page. Car-B-Ques suck.ya, tires and paint burning make the marshmallows taste funny. Link to comment Share on other sites More sharing options...
zayres29 Posted January 31, 2011 Author Report Share Posted January 31, 2011 that almost sucks cause the oil thats in it is brand new Btw that was the first person. Ever banned by me while dropping a deuce. Feel privileged Link to comment Share on other sites More sharing options...
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