Hey all I have a mild sbo that's had a relatively quiet thud for about a month and a halfand today after countless hours of searching I have narrowed it down to what I believe is the #1 cylinder it doesn't sound like rod knock imo. Its a slower knock and id be hard pressed to hear it above 1500rpm. It only knocks when fully warm and has been causing it to idle sort of rough whenever the knock is apparent. When I pull the plug wire on that cylinder it gets much louder. No it is not the flexplate or converter I have checked those dozens of times in the past month and had both out. Any opinions would be great, hoping to get my daily driver healthy and back on the road again! I can get a video tomorrow afternoon.

 

What is your oil pressure?

 

when i checked last month it was 14 at idle fully warm
i am trying to get my hands on another tester at tge moment to recheck

 

How do the plugs read? 14psi at idle warmed up isn't bad. How many miles on the engine ?

 

Plugs all replaced 3k ago and show only normal wear. I was told it was rebuilt at some point but not 100% sure it was. Mileage is unknown

 

It will certainly help many guys here once you post a video of it started up cold idling, then giving it a few throttle blips.

Eric

 

Might need to try a 3/4 race cam in it.

 

I will definitely get a video tomorrow, completely spaced this afternoon

 

not sure throwing a Cam in would solve my problem here and besides it already has a decent street cam

 

If its not a valve train noise, anything in the belt driven accessories, or fuel pump, you'll have to dig into the rotating assy.

 

if the noise as you say, "gets MUCH louder" when you pull the #1 spark plug off, I would suspect a loose "piston wrist pin" or something piston ring related?

 

I was thinking wrist pin also. Was it rebuilt or just a top end job?

 

Has the engine overheated or have you too much advance in the distributor?
Reason I ask is something similar happened to me and the distributor was way too advanced and caused a piston to collapse, still ran but knocked........thanks to a couple people on this site for the diagnosis.

 

I was told bottom end was but am not sure .
I did the top end myself but that was months before the knock started

 

car hasn't overheated in the last year and a half. Had a leaky head gasket error on my part, but was found less than a minute after starting so I doubt it damaged anything that was last year. Timing is pretty conservative because it isn't daily I didn't care to squeeze all the timing I could

 

Here is the video I just took I misspoke and said passenger side in the Vids ignore that it's kinda hard to hear unless you have headphones or when I pull the plug wire and if it is a wrist pin what kind of damage can that do cause I don't have the money to tear it apart and most likely won't be able to until early next year

 

Any chance its a header tube contacting the frame or some other exhaust component contacting the body or frame?

Thanks for posting a vid, just can't tell.

 

It was on the passenger side and I moved it away so it wouldn't but no exhaust is hitting anymore. The way it acts when I pull the #1 plug wire leads me to believe its internal just not sure what it could be

 

Alright so my new oil pressure tester came in and results better than I expected 18psi hot idle and 40 when revved or at 2200 I did pull a little timing from 13 down to 11 degrees it made it a little better, but now I noticed when revving real quick to like 2k from the throttle body as its winding down it knocks more, so I'm thinking wrist pin can anyone confirm?

 

I was at a similar point like you when my mechanic friend looked at me and said, let's pull the engine, sorry to say, but you can't outguess some things.

 

I can't hear ***** drive as normal

 

I know I'm just pulling at straws, but I just down have the money right now to pull and rebuild. And I also can't afford to have it down too long as it is my daily driver. Just hoping at this point

 

I felt the same way watching the video but my phone can't really pick it up in person it really makes me feel uncomfortable taking it on long trips now

 

I can't hear it either with the video. Do you know anyone close that can give you a professional opinion?

 

Yah my dads friend owns a shop about 10miles from me I'm stopping by there on Monday was just hoping maybe it was something g simple that I haven't thought of and I could do myself. I'll do everything but touch the bottom end that is where my comfort zone ends

 

Thanks for posting the video, its very difficult to tell with that video, this is a long shot since you think the knock is coming internally from #1 cylinder but, any chance it could be your water pump impeller?

Eric

 

I have only had one engine that had wrist pin knock and it went forever with no issues. I couldn't hear what your problem might be (even with head phones) but on my engine it was only noticeable at low rpm and went away at a little above idle. If mine I would run it carefully for a while and if it gets worse or the oil pressure drops noticeably then I would reevaluate... Just my thoughts...Tedd

 

I doubt it its a new water pump and sounds smooth through the stethoscope. Using the stethoscope it is loudest near the header for the #1, front of the intake and driver side on that front part where the stamped numbers are

 

Just needed some reassurance like that because I daily the car not pushing it too hard and won't have the money or time to rebuild till next year. Knock doesn't sound deadly but just didn't want to chance it and just blow it up

 

I like what Tedd mentioned. I hope it runs decent enough until you can dig into the engine.

Eric

 

Yah that made me feel a lot better. It just runs a little rough at idle but cruises smoothly the only good thing about the knock and running a little rough is people at stoplights and gas stations think I have a monster Cam and I find the reactions hilarious