I think my flywheel is loose? (1 Viewer)

Pighead

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I've had this new sound in the Pig for about a week now...an irregularly irregular thumping at idle, down low in the block. It goes away at a faster idle or acceleration but comes back on deceleration. This morning it was louder and I said to myself "That is not a good noise." So I dropped the pan, thinking I was looking for a bad bearing. Now, this engine has almost 6 years on it since it's last rebuild. But I did the rebuild. There's no metal in the pan, crank and rods look OK, I haven't pulled any caps yet, 'cause I rotated the engine via my hands on the flywheel...and I felt just a teeny bit of play between the flywheel and the crank. Just a smidgen of play, Just a hair....But is this my new noise?
Oil pressure gauge (mechanical) has been unchanged.
I'm thinking that my next move is to pull the transmission, I don't think there's any shortcut for getting to the flywheel bolts, right?
 
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There should be absolutely no play between the crank and flywheel. you will need to pull the trans and clutch to get at the bolts., no shortcuts there. Did you check the crankshaft endplay (forward and back in the block) while you were in there?
 

Pighead

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Did you check the crankshaft endplay (forward and back in the block) while you were in there?

Well, I'm still in there...probably will be for a day or two. I put my biggest pry bar in front & back of the flywheel, can't move it fore or aft at all.
 
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Normally a low frequency thump is a main bearing problem. A higher freq. popping sound is a rod. Don't forget to mark the caps before removal. Pictures of bearing are always cool.
 
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Greg, you know there should be 0 play at flywheel. Pop the bearing caps. . to look and then pull trans. It could be wrist pin or rod bearings too. You got your work cut out for you.
 

Pighead

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I wish I had a camera that worked. I popped 2 bearing caps, they look almost new.
In fact, I'm pleasantly surprised with how nice everything looks in there. Cam lobes and cylinder walls look pretty darn good for the way I drive it. And if it was a bearing going bad, wouldn't it have shown on my oilpressure gauge? I'm thinking less and less that it's a bearing.
I'm not gonna look at any more until I rule out loose flywheel bolts.
I haven't pulled this transmission since the doubler went on, might take me a little longer this time. Plus, that Pig trannyhump is a real pain to get off...



EDIT: But, you do find some great stuff when you pull your bucket seats out, and I can shake 6 years of Pismo sand out of what's left of my carpet.
 
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If the engine were running we used to isolate by removing spark plug wires one at a time and shorting it to ground (old school). This would isolate a knock to a specific cylinder. Could be a broken piston. If it was a slower knock (half time)it could be the cam. I would probably start with plasti-gauging the mains and work your way to the rods. Look up into the cylinders and look for piston cracks. If you end up checking the rods then look for side/end play. Hmm...
 
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wouldn't it make the most sense to fix the flywheel issue first, then see if the sound is still there. before ripping the engine apart?
 
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Well yes, I thought the flywheel was a past issue. I would think the flywheel would make noise anytime the engine speed changed or at idle. Thanks cruisernerd, missed that.
 

Pighead

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wouldn't it make the most sense to fix the flywheel issue first, then see if the sound is still there. before ripping the engine apart?

Yup, but I kinda had to take the pan off, just to look. And had to take off just 2 bearing caps, just to see...will refrain from undoing anything else before I put a torquewrench on the flywheel bolts to either confirm or deny that they're the problem.



Well yes, I thought the flywheel was a past issue. I would think the flywheel would make noise anytime the engine speed changed or at idle. Thanks cruisernerd, missed that.

Nope, haven't quite got to the flywheel yet. Almost though, got the tranny hump off. Gotta rig up the sling for the tranny/etc...gonna do the support it from above technique instead of the jack it from below method...
Flywheels usually don't make noise, I think.
 

Godwin

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Checking the flywheel is a good idea. My 40 developed a similar sound a few years after a clutch installation and I (incorrectly) attributed it to the throwout bearing. Noise persisted for weeks, at the time this was a DD, until I lost clutch operation. Upon inspection I found that 2-3 of the flywheel bolts had backed out. They would have been torqued to spec, but I think I had forgotten to use loctite at the time of installation.
 

Pighead

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well, it's about a 20 year-old MAF carpet kit, badly modified for the triple-sticks. Threadbare , worn through were it covered a bolt head...
Now that you mention it, I may be better off without it.
 

Pighead

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That was it all right. Loose flywheel bolts. 3 were finger loose, 1 was backing out.
Glad I found it before all heck broke loose.
 
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That was it all right. Loose flywheel bolts. 3 were finger loose, 1 was backing out.
Glad I found it before all heck broke loose.

Oooh, good save. Did you use loctite when you assembled everything several years?

Glad you found it in time.
 

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