Mechanics

ENGINE PING

1999 GMC Suburban • V8 4WD Automatic • 133 miles

I have a 1999 GMC Suburban with 136,000 miles. 5.1 liter. The engine pings at idle or when I am accelerating or running on the highway. It seems some what intermittent. It not noticeable when the engine is cold. But when the engine warms up the knock or ping can be heard all the time. What is causing the Ping?
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Davecincy
December 22, 2010.



Usually a ping(pre-ignition/detonation) can be in direct relation to fuel quality, a timing issue, incorrect spark plugs, or malfunctioning EGR system. Has this been occurring for some time? Has it occurred over more than one tank of fuel? Has any repairs been performed recently that may be relative. And is there a check engine light? Typically, unless the concern is drastic, you don't have a ping at idle. Is it possible that this could be engine noise(top end).

Factoryjack
Dec 22, 2010.
It has been occurring for more than one tank gas. Only repair was the serpentine belt was replaced. No check engine light on. Not sure what you mean by engine noise (top end)? It is more than a acceleration ping. When it starts pinging it occurs all the time.

Tiny
Davecincy
Dec 22, 2010.
The noise maybe more of a tapping sound. Could it be a lifter of valve tapping.

Tiny
Davecincy
Dec 22, 2010.
That is what I would refer to as top end noise. I don't see much in the way of these vehicles pinging, the timingis electronically controlled, and by way of knock sensor(s), the ECM can fine tune it to reduce the occurrence of a ping. Internal engine noise can be a bit difficult to isolate accurately. It could be a faulty lifter that starts making noie as the oil viscosity thins as it warms. If you can develop a suspect side of the engine, you may be able to run it with the valve cover off, and see if applying pressure to a rocker arm can change it. This can be a messy ordeal as the pushrods are going to spit oil. If it is doing it consistently at idle, the spillage may be minimal as the speed is low. You might even be able to identify it without it running by depressing on the rockers. None should be easily depressed by hand, or have looseness. I believe that your motor may have roller type rockers, and are non adjustable.

Factoryjack
Dec 24, 2010.