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underhood shrieking

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Hello all,
I just got my 68 Sprite out of winter storage and happily it fired right up and ran great but I have a situation where it sounds like a generator or belt sqeel on engine decell. I checked the belt and oiled the generator but that didnt help . It seems as if the noise is comming from the rear of the engine and I can make it stop by slightly lifting the drivers side of the engine with my hands under the carbs. My motor mounts are new and it doesnt move exessivly. I'm thinking could this be the starter gear.Does anyone have any idea of what may be causing this? Any help would be great.
Thanks,jv
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spritenut

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Maybe the carbs are loose, or the manifold gasket blew.
This would cause a whistle and wiggling the carbs would change the pitch.
Or maybe the waterpump and/or generator bearing is going.
To see if it's the pump or genny, disconnect the fan belt and start it up and run it for a minute or so and see if the noise is gone.
One last thing, how about the pilot bushing? You mentioned it sounded like the back of the engine. With the noise heard, lightly step on the clutch pedal, if the noise goes away, it's the pilot bushing.

Frank
 
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Hi Frank, Engaging the clutch doesnt effect the noise and it has a new pilot bushing. I did notice that the noise would stop when I unplugged a spare fitting on the intake manifold so your probably right on about the carbs,manifold . Just putting light pressure under the carbs makes it stop not just change pitch. I'll get out in the morning and see if anything is loose on the intake and carbs. I never heard a manifold leak so high pitched and shrill, it sounds like a screaming bearing. But it does sound as if it is comming from the area by the rear carb and manifold. Thanks for your help Frank I,ll let you know how it pans out. Jon
 

Dave Russell

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[ QUOTE ]
Just putting light pressure under the carbs makes it stop not just change pitch. I'll get out in the morning and see if anything is loose on the intake and carbs. Jon

[/ QUOTE ]
Hi Jon,
On engines where the intake & exhaust manifolds share a stud/washer, it's very important for the two flanges to be the same exact thickness. If they are not the same, the only way for the washer to put pressure on the "low" flange is for the stud to bend slightly sideways.

The stud won't bend, so the high flange gets all of the clamping pressure. The cure is to put shims under the washer on the low flange so that both get equal clamping pressure. In your case, the intake manifold flanges may be slightly thinner.
D
 
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Hi Dave, that is very interesting news.It's starting to make more sense now. I will check that for sure in the morning. I have a feeling You and Frank have me on the right track for a fix on this. I will let you guys know how it goes and thanks for all the great advice.Jon
 

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Do you (did you) have a cat? /ubbthreads/images/graemlins/smile.gif
 
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Once again Frank and Daves advice hit the nail right on the head.I shimmed the intake this morning and the problem is solved. I forgot how tough it is to get to those studs and nuts for the manifolds but it was an easy fix. With your help I was able to excise the sceaming harpy from under my bonnet. JP, all the cats are present and accounted for, but not for long if they dont stop climbing on my softtop /ubbthreads/images/graemlins/devilgrin.gif! Frank and Dave thanks so much for your quick responses that have always solved my problems, you guys are the best! And of course thanks to Basil for giving these two Sages a forum where they can help a less knowledgeable bolt buster such as myself. Thanks again, Jon /ubbthreads/images/graemlins/savewave.gif
 
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