Inliners International Forums General Discussion Hi Performance Mystery Knock

My freshly rebuilt 235 was running great. It has about 1000 miles on it. I have been driving it a little hard lately. The other night I was getting on the freeway, and started to get on it. I dont have a tach, but I am pretty sure it was near redline before I shifted into 5th. I went about one mile til the next exit, and stopped at the first gas station to fill up. Every thing was fine when I shut her down. After I filled her up, and grabbed a bite to eat I started her up, and heard a knocking. I let it idle for a minute to try and place the noise, but the motor died. I started it back up and noticed that the car ran fine, but had a pretty loud knock that wasnt constant. It only did it mostly on idle. I drove the 2miles home and shut it down for the night.

The next day, I pulled off the valve cover and side cover. didnt see anything wrong, the valves were out of adjustment, but the noise was louder than unadjusted valves. When I started it up, everything looked fine. Then for awhile the knock went away. I tried reving it, and keeping it at idle. After a couple minutes the noise came back, but not as loud.

I have no idea what I should do next. I was thinking of pulling the motor to reseal the rear main and or oil pan. Maybe I will find my mystery knock at the same time.

Any suggestions? Cam? Wrist Pin? Rod?

my noise was loose flex plate bolts. tom

Check the flywheel first as Tom sugests. Did you use the factory style lock plates?

I didnt use the lock plates, mine didnt have them when I took it apart. I did use red lock tight, and about 100lbs of torque to install each bolt on the flywheel. Before I pull the engine, I am going to pull the Tranny. That way I can start it up and listen again. Do loose flywheels knock? I had a VW that had the flywheel come off on the freeway, it didnt knock as a warning. It did however scare me worst than any other driving mishap.

C;

Don't go to all that work. Just pull the cover & rock it 'back & forth' (in rotation). You'll know if It's loose.

Those lock plates are a MUST on those.

Sorry.

Do you have decent oil pressure while knocking?? and is it coming from the back or front of the motor. I have seem many 235/261 have a knock when you have a broken tooth on the timing gears, the old fiber just gave up,

I had a weird knock at idle I could not find that turned out to a loose harmonic balancer with a wallowed out keyway. I found it by grabing a fanblade a jerking it back and forth. Easy enough to check. Good luck

I climbed under the car and turned the flywheel by hand and had my lady watch the harmonic balancer, they both moved together. I am now thinking the tranny might be giving up its ghost. I got ot from a junk yard, sealed it and threw it in. I also tend to be a little rough on my cars.

I dont think it was it is a timing gear tooth, cause I put new aluminum gears on.

I am leaking oil out of the rear main, which drives me crazy on a fresh built motor, so I plan on pulling the thing out to reseal it.

I am a little more concerned now, cause the knock went away, but it seems to be burning a little more oil. I dont know if that is the leak getting worse, or maybe a brocken ring. I'll update after I get it torn apart again, after the Goodguys West Coast Nationals.

Bring the Motor up on compression Then Turn the dampener & flywheel Counter clock wise This is How you will find out If you have One or the Other Lose.