350TBI 1500RPM engine knock

[Andrew Barker]

How about a lifter? You said the oil was black. Can you hear it at an idle too? A rod knock doesn't get better with a warm engine so that seems unlikely IMO.

Nope not at idle either. Only 1500rpm. I don’t think it’s a rod knock either

 

[thinger2]

Also, I can’t use a mechanics stethoscope just because it only makes the noise while driving the car

Thats also interesting. Mine only made the noise when in gear and driving too. And at weird random times.
What Richard posted earlier about the flexplate "ringing like a bell" when it is disconnected is very true.
We use a similiar process for checking spot welds on certain types of fabrications.
If it rings it good, if it thuds, its a dud.
I would get under it and try to move everything from motor mounts to trans mounts to heat shields before I pulled it.
But I would also take a real close look at the starter gear and the flexplate teeth.
Please let everybody know what you find

 

[Andrew Barker]

Thats also interesting. Mine only made the noise when in gear and driving too. And at weird random times.
What Richard posted earlier about the flexplate "ringing like a bell" when it is disconnected is very true.
We use a similiar process for checking spot welds on certain types of fabrications.
If it rings it good, if it thuds, its a dud.
I would get under it and try to move everything from motor mounts to trans mounts to heat shields before I pulled it.
But I would also take a real close look at the starter gear and the flexplate teeth.
Please let everybody know what you find

My current plan of attack is to first just do a visual inspection of the starter and flywheel while having the car up on a curb. Then take it to my school and put it on the lift there while someone holds it at 1500 rpm while I’m under it. Then unbolt the flywheel from torque converter, push it back, and hit the flywheel with a wrench

 

[thinger2]

Get yourself a tool like this. Its designed for turning flywheels.
You can do it with a big damn screwdriver but its a pretty slow process
Either way,
Dont try to turn it over by the crank bolt unless you pull all of the plugs first.
A sbc crank bolt can snap right off in the crank end if you arent carefull.
Pull all of the plugs first

You must be registered for see images attach

 

[Erik the Awful]

Buy the Summit or Lisle version. The welded tab on my $20 flywheel turner keeps flexing and two weeks ago it slipped and I punched myself in the forehead.

 

[someotherguy]

Buy the Summit or Lisle version. The welded tab on my $20 flywheel turner keeps flexing and two weeks ago it slipped and I punched myself in the forehead.

Holy crap.. I hate when tools let go. I about took out my teeth when a brand new 1/2" drive Craftsman socket broke while I was using the big flex handle ratchet to remove some trailer hitch bolts. By hand!! Not with an impact.

Anyway, I've had pretty good luck turning the flexplate using channel locks, but the correct tool would definitely make it an easier job. If one doesn't mind spending a couple bucks on a good one..

Richard

 

[Andrew Barker]

Get yourself a tool like this. Its designed for turning flywheels.
You can do it with a big damn screwdriver but its a pretty slow process
Either way,
Dont try to turn it over by the crank bolt unless you pull all of the plugs first.
A sbc crank bolt can snap right off in the crank end if you arent carefull.
Pull all of the plugs first

You must be registered for see images attach

Jesus. I guess I got very lucky. I didn’t check this till right now. I turned it by the crank bolt. It didn’t snap off

 

[Schurkey]

I haven't seen the bolt break, but I have seen the crank threads strip.

 

[C30454]

Stop EVERYTHING! The torque converter bolts aren't tight. This will make noise just like a rod knock, but it will come and go under the exact circumstances you described. 10 minute fix.


Tom

 

[someotherguy]

Stop EVERYTHING! The torque converter bolts aren't tight. This will make noise just like a rod knock, but it will come and go under the exact circumstances you described. 10 minute fix.


Tom

Good call, but if he's going to check the flexplate for a crack, first thing after pulling the inspection cover is removing the TC bolts. I think he'll notice if they're loose.

Richard