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Discussion Starter #1
Hi, new to the forum. Read some of the posts and find everybody's very helpful. Just bought a '93 Spider with auto transmission. Noticed a whining or whistling noise from behind driver's seat and it gets louder when you depress the accelerator, stops (or barely noticeable) when you release the pedal. My mechanic says its the LSD but I have my doubts. Any help appreciated. Thanks
 

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What type of oil is in the differential? Is there enough?

Does the noise change if turning? Is it different if you are turning left or right? The outer axle bearings are a sealed bearing - not lubricated with the differential oil. Usually when they begin to fail they make a rumbling/whining noise. When you turn you will put extra load on the outside wheel and its bearing. This extra load (or less load in the case of the inboard bearing) can make the noise change.

Does the Series 4 Spider ('90-'94) have a MAP sensor (manifold sensor) located anywhere in that vicinity? When a MAP sensor fails they tend to leak & whistle. The whistle will vary with engine load (intake vacuum).
 

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Discussion Starter #3
ghnl,
Thanks for the response, the noise doesn't change with turning. It's just gets louder and louder when depressing the accelerator (as you speed up) and stop as soon as you lift the pedal. From your reply it would seem that a leak from MAP sensor could be the cause but then I wouldn't know where that is being new to the alfa scene :). But have ordered a manual and will try to look that up.
Had my mechanic change to a more viscous differential oil this evening but didn't have time to drive it yet. Still, thanks for your input
 

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On my series 3 it's behind the panel on the passenger side and makes a variable whistle noise.
 

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Please be aware that the noise from a failing/failed MAP (vacuum) sensor will be loudest at idle (when manifold vacuum is high). Increasing throttle lowers manifold vacuum so, at full throttle, the sound disappears.
 

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Discussion Starter #6
ummm....responding to papajam, the noise increases (and not decrease) when revving up! So does that mean that it's not the MAP sensor? and the noise seems to be the loudest right behind the driver's seat (left rear).
Still, many thanks to all of you!
 

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But Mad North-Northwest
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Motronic cars like a '93 don't have a MAP sensor behind the seat. I'd be looking at the rear end first: differential or bearings as stated.
 

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I would clean out the vent on the gas vapor cannister in the trunk behind the trunk carpet near the shock tower behind the driver's seat. It'll make a buzz if getting gummed up.

Best Regards,
John M
 

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Discussion Starter #9
Well, I've clean up the gas vapor canister. The noise still persists. Went looking for a second opinion, it's the differential for sure. Thanks you all for your posts.
 
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