1989 bonneville LOUD knock
#1
1989 bonneville LOUD knock
Hey guys, well after a long absence ive returned with some news and questions on the old gold SSE. way back when i was forced to park it after i encountered some pretty audible valve noise. fearing the worst, i promptly took it home, and pulled the valve covers to see if i could locate the issue. after no success i tried starting her up again, at which point i get a series of loud bangs and knocks while it tried to hold idle for roughly 10 seconds before dying.
Since then ive managed to pull the valve covers again, and pull all of the rockers and push rods for some in depth searching...kind of. I still have no idea whats wrong with her, especially since im afraid to start her up again, in case ive really blown something important.
now im thinking, i can see down into the pushrod holes, and the lifters all seem fine, but is it possible i could have squared one off, or otherwise damaged it? would it help my case if i removed the intake manifold and pulled them all out for a close inspection? beyond that, with the noise i heard last time she ran, is it possible i could have thrown a piston rod?
i can post pictures of the teardown and parts if you want.
Since then ive managed to pull the valve covers again, and pull all of the rockers and push rods for some in depth searching...kind of. I still have no idea whats wrong with her, especially since im afraid to start her up again, in case ive really blown something important.
now im thinking, i can see down into the pushrod holes, and the lifters all seem fine, but is it possible i could have squared one off, or otherwise damaged it? would it help my case if i removed the intake manifold and pulled them all out for a close inspection? beyond that, with the noise i heard last time she ran, is it possible i could have thrown a piston rod?
i can post pictures of the teardown and parts if you want.
#4
forgot to add if you put a stronger magnet near your drain plug for a few days then before checking the oil Via drain plug take it off and any metal shavings should be right there and come out quick
#5
Joined: May 2006
Posts: 29,661
Likes: 34
From: Sheboygan Wisconsin
Damage to the lifters is small, these engines have roller lifters. As for the loud bang, I would pull the spark plugs and inspect them for damage. If you find a smashed plug, then get a borescope, you may have chipped a piston.
#6
These are all awesome ideas, Thanks guys! I have to go to work, but ill start by pulling the plugs and applying a big magnet when i get home. a large sub would do the trick eh?
#8
well, pulled all of the plugs, and ive got no physical damage, alot of spacing between the electrodes. although that just might be me. checked the gap, came out to an average of .060". i also left a speaker on the oil pan, and ill check that in a couple days.
Now into a bit of crude diagnostics here. with all of the spark plugs in generally operable condition, can i rule out piston head damage and/or connecting rod failure. OR would it still be a good idea to get a hold of a borescope, and shove er down the spark plug hole to see whats going on?
Keeping in mind that im trying NOT to remove the heads if i dont have to (its just something i dont want to do) once i drain the oil, and look for shavings, even if i dont find any metal in the oil, could i remove the baffle (if it exists) and look at the connecting rods from below, and then source out a borescope from someone else to see the top of the pistons?
Now into a bit of crude diagnostics here. with all of the spark plugs in generally operable condition, can i rule out piston head damage and/or connecting rod failure. OR would it still be a good idea to get a hold of a borescope, and shove er down the spark plug hole to see whats going on?
Keeping in mind that im trying NOT to remove the heads if i dont have to (its just something i dont want to do) once i drain the oil, and look for shavings, even if i dont find any metal in the oil, could i remove the baffle (if it exists) and look at the connecting rods from below, and then source out a borescope from someone else to see the top of the pistons?
#9
Joined: May 2006
Posts: 29,661
Likes: 34
From: Sheboygan Wisconsin
Not having a damaged spark plug don't rule out a chipped piston. But generally chipping it will smash the plug. If you have access to a borescope, I would still check. If you find metal shavings in the oil, it'* a good chance you spun a bearing. Only way to check this is to drop the pan and visually inspect them.