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Engine knock when first starting

There is an engine knock when the ignition turns the starter and cranks the motor, there is a knocking for four or five times then stops. How can I stop engine knock.

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  • Cars & Trucks Master
  • 17,970 Answers

Hi there:
Firs t suggest to check this information about "engine noses"...
ENGINE CLICKING NOISES
A clicking or tapping noise that gets louder when you rev the engine is probably "tappet" or upper valvetrain noise caused by one of several things: low oil pressure, excessive valve lash, or worn or damaged parts.

First, check the engine dipstick to see if the oil level is low. If low, add oil to bring it back up to the full mark. Is the engine still noisy? Check your oil pressure. A low gauge reading (or oil warning light) would indicate a serious internal engine problem that is preventing normal oil pressure from reaching the upper valvetrain components. The cause might be a worn or damaged oil pump, a clogged oil pump pickup screen or a plugged up oil filter. Using too thick a viscosity of motor oil during cold weather can also slow down the flow of oil to the upper valvetrain, causing noise and wear.

COLLAPSED LIFTER NOISE
Worn, leaky or dirty lifters can also cause valvetrain noise. If oil delivery is restricted to the lifters (plugged oil galley or low oil pressure), the lifters won't "pump up" to take up the normal slack in the valvetrain. A "collapsed" lifter will then allow excessive valve lash and noise.

VALVE LASH NOISE
If you can rule out lubrication-related problems as a cause, the next step would be to remove the valve cover(s) and check valve lash. On older import engines, mechanical lifters require periodic valve lash adjustments (typically every 30,000 miles). Too much space between the tips of the rocker arms and valve stems can make the valvetrain noisy -- and possibly cause accelerated wear of both parts.

To measure (and adjust) valve lash, you need a feeler gauge. The gauge is slid between the tip of the valve stem and rocker arm (or the cam follower or the cam itself on overhead cam engines) when the piston is at top dead center (valve fully closed). Refer to a manual for the specified lash and adjustment procedure. Also, note whether the lash spec is for a hot or cold engine (this makes a big difference!).

On engines with hydraulic lifters, oil pressure pumps up the lifters when the engine is running to maintain zero lash in the valvetrain. This results in quiet operation. So if the rocker arms are clattering, it tells you something is amiss (bad lifter or worn or damaged parts) or the rocker arms need adjusting.

DAMAGED ENGINE PARTS NOISE
Inspect the valvetrain components. Excessive wear on the ends of the rocker arms, cam followers (overhead cam engines) and/or valve stems can open up the valve lash and cause noise. So too can a bent pushrod or a broken valve spring.

RAPPING OR DEEP KNOCKING ENGINE SOUND
Usually bad news. A deep rapping noise from the engine is usually "rod knock," a condition brought on by extreme bearing wear or damage. If the rod bearings are worn or loose enough to make a dull, hammering noise, you're driving on borrowed time. Sooner or later one of the bearings will fail, and when it does one of two things will happen: the bearing will seize and lock up the engine, or it will attempt to seize and break a rod. Either way your engine will suffer major damage and have to be rebuilt or replaced.

Bearing noise is not unusual in high mileage engines as well as those that have been neglected and have not had the oil and filter changed regularly. It can also be caused by low oil pressure, using too light a viscosity oil, oil breakdown, dirty oil or dirt in the crankcase, excessive blowby from worn rings and/or cylinders (gasoline dilutes and thins the oil), incorrect engine assembly (bearings too loose), loose or broken connecting rod bolts, or abusive driving.

Bearing wear can be checked by dropping the oil pan and inspecting the rod and main bearings. If the bearings are badly worn, damaged or loose, replacing the bearings may buy you some time. But if the bearings are badly worn or damaged, the crankshaft will probably have to be resurfaced - which means a complete engine overhaul or replacing the engine is the vehicle is worth the expense.

ENGINE PINGS OR KNOCKS WHEN ACCELERATING
The cause here may be Spark Knock (Detonation) caused by an inoperative EGR valve, overadvanced ignition timing, engine overheating, carbon buildup in the combustion chambers, or low octane fuel.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day

Posted on Nov 06, 2012

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  • Cars & Trucks Master
  • 76,691 Answers

If the noise onlu lasts a few seconds then don't worry about it.

Posted on Nov 06, 2012

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6 Suggested Answers

6ya6ya
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Posted on Jan 02, 2017

losflip
  • 94 Answers

SOURCE: Engine Knock on a 98 Isuzu Rodeo

Most likely it is a rod bearing and motor would have to be dissassembled to diagnose, you might want think about installing a low milege used replacment since it was run 5 quarts low on motor oil.

Posted on Nov 30, 2008

  • 11 Answers

SOURCE: long crank time before starts

Thoroughly clean interior of throttle body especially area where butterfly flap seats and all drillings, use aerosol carb cleaner, check air filter and spark plugs (platinum type only!). Then set idle with a consult unit or similar, engine management must be in service mode to set idle properly.
Also test coolant temp sensor it may be open circuit. If you don't know how to do this ask me.
Forget about earth if starter turns engine over at normal speed.

Posted on Dec 13, 2008

  • 180 Answers

SOURCE: Loud Ticking/knocking Noise From motor; What is it?????

You have a hydraylic lifter bleeding down,they make some good oil additives that should help.

Posted on Jan 21, 2009

bibleman01
  • 334 Answers

SOURCE: RIGHT REAR ENGINE KNOCK AT IDLE 3.5 L

It sounds like a lifter so try using LUCAS it makes the best additive on the market for about anything to do with automotive. The have a oil additive that you can use.

Posted on Jan 30, 2009

  • 23 Answers

SOURCE: engine knocking.

Diesel knock at low RPM and Idle is usually an injector that has a leaky seat or has a needle that has jammed up. The knock can normally be heard quite clearly as being at the top of the motor, run the motor at idle and loosen the injector pipes one at a time if the knock disappears on one pull that injector and have it checked.
If one injector is faulty the others may soon go, better to have them all done at the same time.

Posted on Aug 02, 2009

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