MIDNFauciUSN

iTrader: (8)

ok heres another problem...

was driving home one morning, after tightening by alt./water pump belt... and a really jacked up noise started coming from behind the firewall, the only thing i can desribe it as is like putting a small piston engine into the engine bay. Its a really repetitive grinding noise that gets louder... and longer in duration... maybe about 3milliseconds, you know like a revolution of a cam... as you go through the rpm range (3k+).
my first thought was the tranny... pulled that, replaced with one from an s5... no help there. this is where im at now. maybe the stress of the belt could have messed something up (e-shaft)?? a bearing gone bad? oil pressure is fine though.
what is the worst thing that could happen with an overtightened belt?

oh the engine is a mazda rebuilt, with about 30000 miles... maybe i should have gotten one from kevin....

RotaryEvolution

iTrader: (30)

get a long screwdriver and cup your ear to the handle and place it on various spots on the motor, suspect a failure at the loudest spot where you place the tip of the screwdriver.

you can also eliminate noises by removing the belts for the accessories one by one.

good luck.

uRizen

iTrader: (2)

Never tried that trick. The only hand-tool test I ever remember seeing done is taking a small wrench, placing it against the block, and watching for it to bounce off from mis-firing.

I'll have to try that screwdriver thing out though.

As far as the actual problems goes, I'd do as Karack says and pull the accessory belts until you find the problem, and check the deflection on them. I believe it should be ~1 inch of deflection on each belt. I'd also do a compression test ASAP to make sure all your seals are still in good shape.

MIDNFauciUSN

iTrader: (8)

i would be checking the accessory belts, but the only one i have left is the alt. belt. so what could it do to the ecc shaft if was too tight at around 6000 rpm? i would think it could bend something...

fastest2ndgen

Check the water pump with the screw driver trick, same concept as a mechanic stethascope.

MIDNFauciUSN

iTrader: (8)

so was there any chance of damaging the ecc shaft?

85rotarypower

You'll most likely damage the alternator or water pump long before you damage the e-shaft from an overtightened belt. These use ball bearings instead of friction bearings that the e-shaft uses, which are much stronger, hence the reason they are used in an engine.

Oh yeah, and just because the noise is loud doesn't mean it isn't the alternator or water pump aren't bad. I worked on a car once where the water pump bearings were so bad that it made more noise than the engine.

MIDNFauciUSN

iTrader: (8)

thanx man, im gonna look at that here shortly...