Gasoline engine sounds like a diesel

I have a 98 gmc sierra 1500 with the 5.7 L Vortec. On cold mornings when I start it, it has a metallic clicking sound that increases as the engine speed increases. It sounds like a diesel engine. It only lasts for a couple of minutes, once the engine warms up it diminishes. Could someone give me some ideas of what it might be.

Welcome to AF, one possibilty is piston slap or a sticky lifter, impossible to pinpoint in this environment.

Thanks for the suggestions.

mine does same thing. GM acknowledges a prob on 96-99 w/ 5.0 & 5.7
due to crankshaft flexing because of excessive bearing clearace. it's more
of an internal knocking than a clicking. I also read there is a revised EVAP
purge selenoid because of ticking/knocking when cold. Good luck
people with 99 & up often have issues with piston slap

Thanks for the information.

I have the exact same problem with my 01'. Is there anything that can be done to stop this or is it not a problem?

mine does same thing. GM acknowledges a prob on 96-99 w/ 5.0 & 5.7
due to crankshaft flexing because of excessive bearing clearace. it's more
of an internal knocking than a clicking. I also read there is a revised EVAP
purge selenoid because of ticking/knocking when cold. Good luck
people with 99 & up often have issues with piston slap


Where can this be found? I have to call you on this one, sounds like internet rumor to me. This type of crap would be all over the net like the "dexcool eats gaskets". :rofl:

To the original poster...Sounds like a lifter bleeding down overnight.

GM bulletin # 99-06-01-003
snowman: this is just for 96-99, you're probably suffering from "piston Slap"

What is piston slap? Is it a problem? Should I fix it? Will it be costly?

Google "GM piston slap", you will find very quickly alot
more info than you wanted to know.

you will want to start your own thread
with further questions about your particular prob
since it doesnt seem to relate to the original posting
or the forum police will come after you.
good luck

Google "GM piston slap", you will find very quickly alot
more info than you wanted to know.


Originally Posted by MyTOY
mine does same thing. GM acknowledges a prob on 96-99 w/ 5.0 & 5.7
due to crankshaft flexing because of excessive bearing clearace.

Piston slap is not the same thing. So where can I find the information on the "issue" you state GM acknowledges?

google "99-06-01-003" in the i think 4th link down in the forum there is a link to entire GM bulletin and repair procedure for the bearing knock issue.
My reference to piston slap was only for "snowman"
GM Bulletin No 99-06-01-003
"Engine Bearing Knock Noise (re-support crankshaft, select fit rod bearings)"

I don't think I have piston slap. It is just a recent development this winter. Seemed to happen after an oil change. Once the engine runs for about a block or two it stops and doesn't come back till the next morning. Could it be a lifter? If so how hard is that to fix?

Sno start a new thread this is too old, thanks.