85 Vette with knocking sound
Thread Starter
Instructor
Joined: Sep 2002
Posts: 137
Likes: 2
From: Greenbrier TN
85 Vette with knocking sound
Any ideas? Found an 85 Vette that's worth the money I think but it's knocking at idle. Oil pressure is great and doesn't knock @ higher rpms. Just at idle. Laying under car it's hard to tell where it's coming from. Travels quite a bit. Cracked flywheel? Toasted converter? Cat fallen apart? Or rod knock? Not sure about rod or mains because it doesn't do it throughout higher rpms. 129k miles. Any help appreciated. Thanks!!
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: 85 Vette with knocking sound (hgpreston)
Does it get louder or more quiet when the engine gets to temp? Or does it not change at all.
Take the cover off the back of the plenum to expose the distributor. Then remove one sparkplug at a time and listen closely to see if the knock goes away putting the plug back on after each one.
Take the cover off the back of the plenum to expose the distributor. Then remove one sparkplug at a time and listen closely to see if the knock goes away putting the plug back on after each one.
Thread Starter
Instructor
Joined: Sep 2002
Posts: 137
Likes: 2
From: Greenbrier TN
Re: 85 Vette with knocking sound (scorp508)
Knock doesn't change as temp goes up. Stays pretty constant at all times. Kinda hard to do the spark plug test you mentioned on a test drive.
