I've been having problems with my alternator ever since I got my jdm b18c-r installed. I've read that the pulley on the jdm alternators are a little smaller then the usdm pulleys. Is this true? I have a belt for the usdm alternator, so would a slightly larger belt cause a whole hell of a lot of squeeling when its cold and in lower rpms? What size belt would I need to buy? Also, as I'm driving at night, everytime I get off the accelerator, the lights brighten and everytime I step on it they dim... isn't it usually the other way around with a bad alternator?

 

IMO, the smaller pulley wouldn't make much of a difference. This will only cause the alternator to spin slightly faster.

With belts, squealing is caused by improper tension and/or improper alignment issues. The only thing a longer belt would do, is expand slightly longer from heat. This may cause more issues as the alternator belt is not on a tensioner and will thus, become looser.

With your headlights dimming and brightening, this can be caused by several things:
1) Improper belt tension
2) Failing alternator
3) Failing battery cell(s)
4) Improper engine grounds

A simple way to check is use a multi-meter, and test:
1) Battery voltage with engine off
2) Battery voltage with engine idle
3) Battery voltage with engine revved and held around 3,000rpm
4) Alternator voltage with engine idle
5) Alternator voltage with engine revved and held around 3,000rpm
6) Alternator voltage with engine revved and held around 3,000rpm with aux systems turned on.

Cross reference with a HELMs. Actually the HELMs will probably give you better instructions to check the alternator. Good luck.

 

alright thanks for the quick response... I'll try that

 

Id also like to add that the dimming and brightening of headlights can be caused if the engine idle is improperly calibrated and too low.

 

No, I adjusted the idle perfectly after the motor went in. And they only dim when I'm driving and get on the gas

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 89sparks &raquo;</TD></TR><TR><TD CLASS="quote">No, I adjusted the idle perfectly after the motor went in. And they only dim when I'm driving and get on the gas</TD></TR></TABLE>

You adjusted the idle via the HELM's steps?

If your dimming in a higher RPM, off the top of my head, I would guess that the alternator is going out, as it obviously cannot keep up with the load.

 

Autozone will test the battery and alternator for free.
I had a similar problem and turned out to be simply that the belt was not tensioned properly, so I would suggest double checking it.