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bad alternator, belt too tight?

blondejoncherokee

NAXJA Member
NAXJA Member
Location
sacramento
could a belt that is too tight kill the alternator?
my belt doesnt feel too tight but i made it tighter than usual after replacing the exhaust manifold and ps pump and steering box and a few weeks later the alt is dead. i think its unrelated since i dont think its that tight. anyway the durango alt is an upgrade so ill search. this alternator is a mean green
 
Ouch! Them Mean Greens are a bit pricey.

New belt tension is 180~200 ft lbs, a used belt (after 15 minutes of operation) should be tightened to 140~160 ft lbs. Getting the tension correct is a crap shoot unless you use a proper belt tension gauge.

You don't describe the alternator failure. A belt that is overtightened could damage the bearings.

If this is for the 89 in your signature you should not be looking at the Durango upgrade, that really only works for the Nippondenso 91+ that are PCM regulated.

For the Renix there are higher output CS-130 Delco Remys, as well as the powerful CS-144 series.

Here are two links on Renix charging systems--first covers upgrades, the second is a CS-144 vendor:

http://www.olypen.com/craigh/charge.htm

http://www.alternatorparts.com/CS-144_Special_offer.htm

A good thing to remember is that not all CS-130/CS-144 alternators are created equal. Mostly what that means is there are NUMEROUS uses in GM/Jeep, etc., so you want to make sure the case is correct for mounting--the vendor above will get you set up right. This is also a good point to remember when getting a Renix alternator from the parts store--sometimes the CS-130 with the XJ part number won't fit.
 
its the renix in my sig. i swapped in a 100 amp autozone reman.
the voltage drops at idle though and going slow, and even on the freeway it stays right under 14 volts. im not sure if thats normal since i had the mean green for so long...i was sure to keep the belt kinda loose, so maybe ill tighten it a bit
 
The volt gauge is at the end of the circuit, so every load reduces indicated voltage, plus they aren't too accurate to begin with.

Hook up a voltage meter to the battery terminals and see what you are getting with the engine running at idle.

The problem with some (I really want to say most but if I do someone will prove me wrong) alternators is that their output isn't all that much at low RPMs, the higher the RPMs the higher the output, and by extension the higher the alternator is rated the higher the RPMs are going to have to be.
 
ok good to know thank you joe peters!
i also have the extra gorund on the back of the alternator that goes to the battery (like 5-90 says) and i also have massive gorund cables going from battery to engine, but i still have the threaded strap that goes to the firewall from the engine. should i upgrade that strap to a big ol guy too?
what should the voltage be at idle?
ill get the voltmeter on it after work
 
i did notice now that the new alt is in that the weird noise i thought was coming from the a/c pulley is gone
 
Static battery voltage should be about 12.5, running 13.8~14.5 or so.

I would upgrade the strap to a cable, 4ga or larger. The straps tend to disintegrate. On the early XJs that strap is the ONLY unibody ground--what a choke point! Adding an extra ground cable from the negative battery terminal to the fenderwell isn't a bad idea.
 
yah i have a ground from the negative batt to body. i plan on getting a better ground for the firewall. and the negative coming from the alt. and a huge prob 0 guage wire going to the engine from the battery. ill check the voltage tonight
 
my digital multimeter didnt read anything at the terminals while running but the gauge says 14 now and is fluctuating less. ill be adding some 4 gauge or bigger cable to the battery-alt power cable and the engine-firewall cable to finish up the loop. the funny thing is the weird noise i was getting before that got way worse over time has gone away completely with the new alt. maybe that noise was the alternator bearing going out?
 
i threw on a 2 guage ground wire at the firewall and also replaced the alternator to starter relay thing wire with a 2 gauge wire as well. this makes the voltage on the gauge stay around 14 no problem and the jeep seems to be running alot better.
 
i threw on a 2 guage ground wire at the firewall and also replaced the alternator to starter relay thing wire with a 2 gauge wire as well. this makes the voltage on the gauge stay around 14 no problem and the jeep seems to be running alot better.

Good, sounds like you got it beat! :wave1:
 
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