Motor knocking
Igenofish
04-08-2015, 06:40 PM
I have a 1988 GMC Sierra, 350 4x4
This just started. It runs and sounds fine just sitting there. Whenever I put pressure on the motor while driving, it starts knocking. I can rev it up in Park and it's fine. Only does it under pressure .
HELP!!!!!!!!!!
This just started. It runs and sounds fine just sitting there. Whenever I put pressure on the motor while driving, it starts knocking. I can rev it up in Park and it's fine. Only does it under pressure .
HELP!!!!!!!!!!
maxwedge
04-08-2015, 08:18 PM
You need to have someone listen to this onsite, we can only guess from here.
Igenofish
04-08-2015, 09:25 PM
Sorry, not sure what you mean?
aleekat
04-08-2015, 09:34 PM
He means have a mechanic come to listen to it.
Igenofish
04-08-2015, 09:43 PM
Cedar Bluff , Al. Looked everywhere here. No mechanics. Afraid to drive too far. Surely someone has an idea.
Igenofish
04-08-2015, 09:45 PM
Don't get it. Happened all at once. Should be something simple. No signs at all.
MikeCStig
04-08-2015, 11:28 PM
Usually if it were a rod or valvetrain knock, it would happen at idle, while revving the engine in park, and under a load. When it only happens under a load it's usually a spark knock, which is an ignition timing issue. Not as serious, but it does need to be fixed or it can lead to more serious issues.
Igenofish
04-09-2015, 02:36 PM
Had timing checked today. It's right on. Back to the drawing board.
aleekat
04-10-2015, 12:46 AM
only in drive. then driveshaft, gear box, tranny...etc..
Igenofish
04-10-2015, 10:37 AM
Will lok into that. It's just that it definately sounds like it's coming from the engine. Almost as if it were bad gas. Tried to remedy that also. I'm just lost here.
Stealthee
04-10-2015, 05:58 PM
You need to check your ingition system, from your plugs to wires, to cap to rotor. I bet you'll find your issue there,.
Igenofish
04-10-2015, 06:08 PM
I have replaced plugs rotor button and Cap already. Wires look good in the dark, but haven't replaced them. Truck runs like a champ until it is put under pressure. Driving only. In park, sounds fantastic.
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