Ok my dad has a 1983 chevrolet single cab silverado...

His original engine went out less than a year ago...

ok, he tells me today that its making a knocking noise...

I go outside to listen, see if a header was loose... then i see what I think is a

Big problem..

The back right sparkplug is moving everytime that tick noise comes.... but

the spark plug is not loose..

Now my big question is... Did he drop a valve or something of that nature??

 

I dont know much about engines but I do know what the spark plugs are not suppose to move...

 

hope you get it figured out matt!

 

I'd say it is possible for the ceramic insulator to seperate from the metal in a plug and move about. The ticking would then be spark jumping to the head.

Otherwise it will be ugly.

 

back the plug out. look and see if it is damaged or if it might have broken the threads loose in the head. if that looks OK, take a compression reading from that cylinder. itll either be zero or real low if its a valve problem. if the plug is moving, you got some problems! you can get a spark plug thread repair kit, just like a heli-coil. might just be a broken spark plug though.

another thing.....while the motor is running, pull spark plug wires off one by one. if you pull one wire off and the knock goes away...you found the bad cylinder....thats how i check for rod knocks (spun rod bearings, etc). make sure you get your finger out of the way of the spark!!! i got hit by the MSD system on my cuda once, not fun!
hows the oil pressure? just in case you might have a bad rod bearing, but doesnt sound like it from the way you described it. CHIP

 

I only have a very basic understanding of how enginges work and Im not trying to be a smart *** but even if you pull the spark wire does the piston still get dragged up and down because it is connected to the crank..this is just a question because I hear a tic too and I want to try this. Also is this bad for the engine to do this?

 

orlando...... when you remove the spark plug wire there is no combustion taking place to "drive" the piston back down. thats when you hear the knock, when the rod is being forced back down against the crank. normally this will work to locate the bad bearing.

he said its an 83 model, so its got a carburetor on it. if you did this on a truck like mine, a 2000 model, it will most likely set a code in the computer for a misfire, turning on the SES light.

from the way he described it, doesnt sound like a rod knock, but figured i'd give some extra info if he ran into other problems. CHIP

 

Thanks Chip, I think I understand now. So could I still try this on my truck; a 2001 silverado, and if it sets a code will it reset when I put back the wire? If I do this one plug at a time and the tic doesnt go away then Im guessing more than likely it is the valvetrain or an exhaust leak...its driving me crazy.

 

if you diconnect just for a min it probably wont set a code mine didn't when i for got to hook up a whole side of my truck's coil packs funny thing it idle kinda smooth on 4 cylinders. but no light i just pluged them up real quick. but you could and if you do just disconnect the batt for a min and it should go away.

 

Thanks, when I think about it I didnt torque down one of the plugs all the way and it was so lose I could see it moving around and it didnt throw any codes either