In Search of the Noise

[Italchic]

In my previous post, "new noise" I followed the advice given. Here's the deal: removed alternator and belt-no noise from engine compartment, took alternator to parts store and tested on bench-no noise while spinning. Turned water pump-no noise. Put everything back together-noise is back!!!! I give up. I'm just going to drive it, monitor the situation and wait and see if the offending part does anything to further to indentify itself. By the way removing the alt. was one of the most difficult tasks I've tried. Only someone with arms smaller that those of a small child could even work in that space and then there is no way to remove it from the top and almost no way to get it to drop from the bottom. And then trying to get it back in is even worse. Basically I guess you have to remove about three or four other parts in order to gain access to the alt. The good side is that I only got one smashed finger nail and there was no blood involved. But I 'm no farther ahead as to what's causing the noise. But thanks to all for the advice.

[azruss]

that belt only runs 2 items. the water pump and the alternator. it is possible that the alternator would turn quietly without the belt. afterall the belt puts a big side load on both items. using a stethoscope should isolate the alternator from the waterpump. (mechanics stethoscope is a piece of rubber tubing stuck in your ear and the other end put on the part you want to hear). Also take a quick look at the belt and make sure it isnt rubbing on something. Also make sure your belt isnt too tight. should be able to push the belt down about an 1" between the pump and alt.

[76124]

You may have addressed this in a prior post, but have you swapped out the belt? I had a belt making a buzzing noise forever and thought it was a bearing etc. Little candle wax on the back of it would take care of it for a while until it wore down. New belt took care of it all together.

[bradartigue]

If you have not done so remove the water pump pulley completely. Inspect for cracks. I had a weird noise for a long time in that area until one day the pulley exploded because of cracks emanating from under the bolts (which had been over-tightened, probably by me at some point). I installed a new pulley and a few days later realized that with the hood up nothing made noise.

Things act differently when pressure is applied to them, so spinning by hand is going to hardly reproduce the speed, heat, and off-center pressure applied when a tensioned belt is on there.

Also check the alternator hold-down bracket for cracks or looseness.

[Italchic]

As I said, the alternator was spun at high speed on a bench testing machine using an electric motor and a belt pulled tight to simulate engine load- no noise. Listening to it with a wooden rod while on the engine does produce a whirring sound but this could be just normal mechanical noise due to moving parts within.

[dantye]

As I said, the alternator was spun at high speed on a bench testing machine using an electric motor and a belt pulled tight to simulate engine load- no noise. Listening to it with a wooden rod while on the engine does produce a whirring sound but this could be just normal mechanical noise due to moving parts within.

Good guess this is your problem if you have not already discovered it: Water pump bearing was shot - possibly due to loose pulley bolts - this shows where the pump impeller was rubbing against pump body (on the left side of the impeller circle in photo). This rubbing happens ONLY when pump is installed and belt is pulling on the bad bearing. The noise was how i caught mine - before there was much noticeable coolant leakage or belt or pulley damage. Excess belt tension will always cause excessive water pump and alternator bearing wear - but they wear out eventually anyway.