wrist pin knock

335249 · 12-03-2007, 05:00 PM

Hello all, I have a 98 Z71 5.7 that has 238K miles on it. Can someone tell me the characteristics of a wrist pin knock as opposed to a lifter knock? I think it is the lifters because it was not making the noise until after I had the heads reworked (ran hot and cracked one)

The noise goes away after the motor warms up.

HELP!!!

75K30 · 12-04-2007, 11:28 AM

Welcome to the site;
I do not believe that you have a problem with a wrist pin. The pins in your SBC are pressed into the conecting rod, and it would be terrible diffucult for this item to presesnt itself as a problem.
There is a very good chance that you have a lifter that is being troublesome. Verify adjustment.

Streakn · 12-05-2007, 12:59 PM

Had one that was making a similiar noise but turned out to be the flywheel

Case 7230 · 12-16-2007, 11:52 AM

The wrist pin or small end or gudgeon pin knock is very distinctive. It is a double knock in time with revs. It is unlikely to go away as the engine warms up. A bad lifter makes a single knock in time with revs.

436'd skylark · 12-16-2007, 03:44 PM

Quote:

Originally Posted by 335249

Hello all, I have a 98 Z71 5.7 that has 238K miles on it. Can someone tell me the characteristics of a wrist pin knock as opposed to a lifter knock? I think it is the lifters because it was not making the noise until after I had the heads reworked (ran hot and cracked one)

The noise goes away after the motor warms up.

HELP!!!

depending on how hot the engine got, I'd say you may have some bottom end issues. afterall if a cylinder head cracked, it must have severly overheated the engine. if the noise goes away when operating temperature is reached, something is expanding to take up slack. first thing that comes to mind is a possible collapased piston.

12-03-2007, 05:00 PM	#1
335249 Junior Member Join Date: Dec 2007 Posts: 1	wrist pin knock Hello all, I have a 98 Z71 5.7 that has 238K miles on it. Can someone tell me the characteristics of a wrist pin knock as opposed to a lifter knock? I think it is the lifters because it was not making the noise until after I had the heads reworked (ran hot and cracked one) The noise goes away after the motor warms up. HELP!!!

12-05-2007, 12:59 PM	#3
Streakn Full Member Join Date: Oct 2007 Location: south central ky Posts: 38	Had one that was making a similiar noise but turned out to be the flywheel __________________ 3D graffix, as you can see by the spider, my graphics ain't from a piece of vinyl.

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12-04-2007, 11:28 AM	#2
75K30 Senior Member Join Date: Jul 2006 Posts: 3,312	Welcome to the site; I do not believe that you have a problem with a wrist pin. The pins in your SBC are pressed into the conecting rod, and it would be terrible diffucult for this item to presesnt itself as a problem. There is a very good chance that you have a lifter that is being troublesome. Verify adjustment.

12-16-2007, 11:52 AM	#4
Case 7230 Senior Member Join Date: Dec 2007 Posts: 665	The wrist pin or small end or gudgeon pin knock is very distinctive. It is a double knock in time with revs. It is unlikely to go away as the engine warms up. A bad lifter makes a single knock in time with revs.