Help chasing down engine knock
Posted: Sat Jul 13, 2019 12:29 pm
Hi all,
Seeking some advice on chasing down a knock I have in #1 cylinder. I shorted the plugs and have found #1 cylinder to be the culprit. I have adjusted the rods once and have put maybe 20 miles on it since the initial adjustment two years ago. It is possible it may need another adjustment. Keep in mind this engine (stamped with a 1920 serial number) it is rather tired and things inside are not optimal by any means.
Two years ago, I did all cylinders, but #1 is still noisy. I sanded the original caps to the point I could add a few shims back in and adjusted accordingly. I do realize this makes a rod journal a bit out of round by sanding the cap. The engine runs good otherwise and is pretty smooth. It is firing on all cylinders, i just get a persistent knock, that seems to be most audible at idle (I can hear it driving, just not as bad, maybe due to normal wind noise and such. It sounds like a nasty rod knock.
So I took down the pan again this morning, didn't find much material in #1 dip, #2 and #3 had more than I would have liked to see---but again, its a tired old engine, it just kinda is what it is. Unlike the first time I adjusted them, this time all the rods including my #1 seem tight on the crank, that is to say I can not feel any up / down play on them and they move freely on the thrusts, side to side (front / back on the crank pin).
Could this be a piston slap issue instead that I am trying to chase? I am trying to figure this out without tearing this thing down. I have some of the parts and pieces to build another engine with a Scat crank, I just need to save up and have a good block rebabbited--and a camshaft too. So this one needs to last me a bit longer.
Seeking some advice on chasing down a knock I have in #1 cylinder. I shorted the plugs and have found #1 cylinder to be the culprit. I have adjusted the rods once and have put maybe 20 miles on it since the initial adjustment two years ago. It is possible it may need another adjustment. Keep in mind this engine (stamped with a 1920 serial number) it is rather tired and things inside are not optimal by any means.
Two years ago, I did all cylinders, but #1 is still noisy. I sanded the original caps to the point I could add a few shims back in and adjusted accordingly. I do realize this makes a rod journal a bit out of round by sanding the cap. The engine runs good otherwise and is pretty smooth. It is firing on all cylinders, i just get a persistent knock, that seems to be most audible at idle (I can hear it driving, just not as bad, maybe due to normal wind noise and such. It sounds like a nasty rod knock.
So I took down the pan again this morning, didn't find much material in #1 dip, #2 and #3 had more than I would have liked to see---but again, its a tired old engine, it just kinda is what it is. Unlike the first time I adjusted them, this time all the rods including my #1 seem tight on the crank, that is to say I can not feel any up / down play on them and they move freely on the thrusts, side to side (front / back on the crank pin).
Could this be a piston slap issue instead that I am trying to chase? I am trying to figure this out without tearing this thing down. I have some of the parts and pieces to build another engine with a Scat crank, I just need to save up and have a good block rebabbited--and a camshaft too. So this one needs to last me a bit longer.