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The darndest thing.....?

I have a 2002 Mazda 626 with the 2.0 motor and am experiencing the what can only be described as gremlins. I have owned the car for the last couple years and it has just about 135k miles on it and I take pretty good care of it. About 2 months ago a had an alternator belt pop while driving home from work. The temp shot up of course so I pulled off and let the car cool down. I was only 300 yards from my house but wanted to get it home for the night so after letting it cool off I fired it back up and got home just fine. Well I work at an auto parts store so the following day I picked up a belt, popped it on, set the tension, and went into work thinking the problem was solved. About 4 days later I was on my way into work and I popped the belt again. This time I called a tow truck and got it taken back to the house after confirming that it was in fact the same belt as before. Replaced that belt and it popped again a few days later. I realized that these belts were popping while I had the heat on so I decided to try a test. I started the car and it began to squeal for about 10 seconds and after that it seemed fine unless I had a load on the alternator. So I decided to replace the alternator and call it a day. I replaced it and the problem persists. Well the next option is to check the water pump. The seal in that looked bad so I got a new one and Bam! the problem still persists. the only other component on routed by that belt is the harmonic balancer and I removed it and it seems fine. The thing is I can drive the car with no electrical components running and it runs fine after the initial start up/squeal fiasco but when I roll the window down or turn the A/C on the idle drops sporadically around 500rpm. While driving I can use these components and can actually feel the stress it is putting on the engine. It doesn’t feel as (dare i say it) “peppy”.

Now to clarify I have installed a higher quality belt than the first several that I broke and have yet to break it but I am still having problems with the idle. All of these problems started a week or 2 after installing a spiral cell battery. Is it possible that there is a connection between the battery and the idle being unstable or the belt popping? Any ideas on what the problem could be if not the battery?

Something is out of line or loose, its the only way it would come off.
Check for loose bolts,bearing and bent parts.

Seizing A/C Compressor ?

It sounds like the one sepentine belt runs the alternator, water pump, and A/C, etcetera ?

Try buying a belt for the 626 model that did not have the A/C option and install it, eliminating the compressor.


As I see it, the possibilities are:
A bent/out of alignment pulley or tensioner
A bad bearing in a pulley or a tensioner
An A/C compressor that is going bad and is about to seize up

CSA’s suggestion is a good one. Give it a try in order to determine if the compressor is the gremlin.

I Looked At What I Think Is The Belt Diagram For The 2.0L.

It looks like there are 2 belts. One for alternator and water pump, and one for A/C with an idler pulley and the P/S pump, I think. Picture is confusing by trying to cover several configurations.


There are 2 belts on this vehicle. One runs the PS pump and A/C the other (the one that is causing problems) runs the alternator and water pump. the alternator and WP have both been replaced and all is installed correctly. The true kicker to this entire situation is that i can crank the car normally and it will do the squealing that i have mentioned but if i shut it off and remove the voltage regulator it starts perfectly quiet. it did this on both the old and the new alternators so i don’t think its the alternator but perhaps something else entirely.

p.s. all the belts have been replaced and tension is good. tension is held on the alternator side by the alternator itself. the A/C and PS is held by the PS pump. all screws are tight and nothing simple has been overlooked. i have 2 room mates that are both great with cars (we all work for the same company and have been working on cars since we were in middle school) and both have uninstalled and reinstalled my work and get the same results.

I think one of the main clues is that when you remove any loading (or the voltage reg) the problem goes away. I think the alternator is going full on with even a modest load and that is causing the belt load to exceed its capability.

I’d bet you have a bad electrical connection that is causing excessive voltage drop, made proportionally worse with load. That is affecting the alternator sense circuit and it goes full on.

You could verify this by measuring both voltage and current. You work at an auto parts store, do you have access to a clamp on ammeter? Measure the current being drawn at idle and then when you operate a window motor for example. Also verify the alternator output voltage under those conditions.

It wouldn’t hurt to do a visual inspection of the critical points; battery terminals/wires, chassis and engine grounds and the alternator sense circuit. If you have a separate voltage regulator, make sure it’s working correctly too.

Thank you very much for the insight. I added another ground from the battery terminal to the motor mount, adjusted the tension on the alternator belt (i had not tightened it after the break in period. dolt!) and replaced the pcv valve and the car purrs like a kitten. thanks again for the insight.