Need help on noise diagnosis

74EMPI · Post by **74EMPI** » Fri Jul 12, 2002 2:12 pm

I posted previously about starting my rebuild for the first time and having a strange noise. I had some time to work on it today. I made sure all the tin was tightened down, fixed the broken bolt that holds the fan to the shroud and checked to make sure thee was no tin hitting anything. Started the engine up and while driving the noise is like a crunching/grinding/knocking noise.(almost liek the flywheel is grinding against the bellhousing) I can turn the engine by hand and there is no noticeable noise or binding. Got out with the engine running and noticed that the crank pulley was wobbly. Stopped the engine and had a close look. The pulley is bent. I am going to replace it tommorrow. Would a bent pulley cause alot of noise?

Any other ideas?

Mike

Air-Cooled Head · Post by **Air-Cooled Head** » Fri Jul 12, 2002 2:28 pm

If the pulley is wobbly, it could possibly hit the rear tin. But that would be a scrapy type noise. Crunch may be similar, but knock? Try this late one evening. Take it for a short drive and get up a little speed, push in the clutch pedal and off the gas. Still hear it while coasting? Try coasting w/ engine off. (don't lock the steering wheel!) Still hear it? What you're trying to do is isolate the noise to either engine, or something wheel related.
Good luck.

carapace · Post by **carapace** » Fri Jul 12, 2002 2:48 pm

Didja tighten the flywheel?

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Simon Sez
www.carapace-design.com
Bad Dog Racing-www.gregsvw.com

Tanbug · Post by **Tanbug** » Sat Jul 13, 2002 5:07 am

A bent pully can crack the fan and will make noise at certain RPM's. Makes a hell of a rattling sound. Got headers? Are they banging on the body?

74EMPI · Post by **74EMPI** » Sat Jul 13, 2002 7:35 am

Update

I removed the pulley today and out of curiosity I started the engine without the fan belt to eliminate the fan. The noise is still there but not as pronounced. It sounds like something is hitting the body but when I look closely there is nothing that I can see. My last engine had dual quiet packs and I am now running the stock exhaust with j-tubes. I can hear alot more lifter noise so is it possible that engine noise is just more noticeable with the stock exhaust?

Mike

[This message has been edited by 74EMPI (edited 07-13-2002).]

74baja1915 · Post by **74baja1915** » Sat Jul 13, 2002 11:53 pm

Well after reading your last post i don't think this is it but hey i'll out it out there anyway. i had a noise problem with mine when i first got it and it was the fan at high rpm's would rub but at idle it would not and it drove me insane for awhile.

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If its not broke don't fix it, but if it can be made better by all means do it!

74EMPI · Post by **74EMPI** » Mon Jul 15, 2002 9:23 am

What kind of a noise does a loose flywheel make? I know that I torqued it correctly but at this point I am not really sure about anything.

Thanks for the replies.

74EMPI · Post by **74EMPI** » Wed Jul 24, 2002 1:23 pm

Chad,
most of my noise appears to have been valve train issues. Had the dist drive gear off 180 and didn't adjust the valves to match. The remainder of the noise appears to be exhaust leak on #1 and maybe a misfire due to bad plug wires.

Good luck.

Post by **Marc** » Wed Jul 24, 2002 1:50 pm

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Chad's 62:
...hear it when in the car and it sounds like a low grumbling noise.<HR></BLOCKQUOTE>

Have you already tried removing the fanbelt for a minute to see if the noise stops?
If the fan-end bearing goes bad the resultant noise is a low rumble. Usually you can feel a little bit of radial play in the fan if it's bad enough to need immediate attention.
Alternators that carry the bearing directly in the aluminum casting rather than in an iron endplate like generators are more likely to have a problem (and the only way to fix them is to mill off the end and fit a cast-iron endplate).

74EMPI · Post by **74EMPI** » Wed Jul 24, 2002 4:29 pm

Marc,
I have disconnected the fan belt and the noise stays. I think some of the noise is exhaust leak. I work Sun-Wed so tomorrow is my day to work on the car. Hopefully I will have it all sorted out soon. I will post anything I find. Thanks for all your replies.