Why is my bell housing knocking!

[projo198]

Just rebuilt and installed this 350 sbc, connected to a manual transmission.

At first I thought I had a motor knock, but with a stethoscope this is definitely coming from the transmission.

Was not an issue before the motor swap, any ideas what is causing it and where I should start?

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[YakkoWarner]

Clutch housing bolt backing out? If it was an automatic I'd start with the torque converter bolts but since its a manual those aren't in existance. I would pull the inspection cover and rotate the engine by hand, look for anything the appears shiny or rubbed like its been hitting something else. Did you reuse the flywheel? I never had a flywheel go out of true but if it is running with a slight wobble it could be tapping on the starter.

 

[projo198]

Thanks! I did thst and didn't see anything. When I assembled i did not have an alignment tool so I measured as best I could. Tonight I pulled the transmission and tomorrow I'm going to reinstall and re-torque everything.

 

[Ricko1966]

Thanks! I did thst and didn't see anything. When I assembled i did not have an alignment tool so I measured as best I could. Tonight I pulled the transmission and tomorrow I'm going to reinstall and re-torque everything.

Did you install a pilot bushing? Has the flywheel loosened up?

 

[vr1967]

Hydraulic bell housing and 3 finger clutch? If so, check to see if the fingers are hitting the throw out bearing lever. I did that once, and it sounded just like in the video. Had to go to a diaphragm clutch for a later model in my case, as I was installing a hydraulic bell housing in my 82 that originally came with mechanical linkage.

 

[Chevy 88]

Do you have an assistant?

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[projo198]

Thanks all. I have the transmission pulled away from the motor but have to get a transmission jack to get out of thr way today so I can get in there.

Did not replace the pilot bushing.

More to follow!

 

[Ricko1966]

Thanks all. I have the transmission pulled away from the motor but have to get a transmission jack to get out of thr way today so I can get in there.

Did not replace the pilot bushing.

More to follow!

Is the pilot bushing there?

 

[Chevy 88]

You might be able to put ratchet straps between the frame rails and let the trans rest on those. Then you can slide the trans back on the straps.

 

[projo198]

Well transmission is out but there is no obvious damage or metal on metal. I now have a n alignment tool and it does not appear to go all the way into the motor. If not perfectly aligned could this be the knocking sound?

 

[projo198]

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[projo198]

Is the pilot bushing there?

So I just pulled the clutch and im not seeing a pilot bushing at all. Just an open hole!

 

[Ricko1966]

Well I think I know what the problem is. Cranks do not typically come with a pilot bushing installed. Not all cranks are even machined for a pilot bushing so,things could be worse. I wondered if you needed to install one and didnt. Easy fix.

 

[projo198]

I got it in and the transmission bolted in last night. Hoping to have everything back together this weekend. Thanks!

 

[projo198]

Well funny thing, although I was missing the pilot bushing it was actually a bent access cover that was causing the knocking.

Sucks I pulled the transmission to determine this, but lucky I noticed the missing bushing while I was doing it!