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Discussion Starter · #1 ·
the updated document is here: http://www.b15u.com/general-maintenance/29321-alternator-belt-how.html

last edit: 6-20-2012 5:34am - added tips & new step 15

i would like to thank everyone involved here at b15u.com for great info and influence for this write-up. this write-up was created to add pictures and references for serpentine belt and alternator installations.

this write-up is for 02-06 nissan sentras with 2.5 liter motors. other applications may be similar, ie altima.
***for BELT ONLY, use steps 3, 4, 5, 14, 15, and 18.***
***if youre installing A HEADER, make sure your lower spring bolts come off before continuing.***
***ANY BOLT you are going to use again, be sure to put small amount of anti-seize on the threads for all bolts removed in this write-up before inserting the bolt into its location.***

safety and precautions
first off, please everyone make sure and be aware of what youre doing. it is always good to have a friend to help, or an experienced friend if you dont know what youre doing. you need to lift your sentra off the ground which may involve using jacks and stands, never sit/lay/poop under the vehicle, make sure the vehicle is stable before wrenching. you will be working with your vehicle's electrical and charging system, which means there is a live wire on your alternator, under the red cap, make sure you disconnect both battery terminals, always disconnect negative terminal first. otherwise, you may cause fire, injury, unintended welding, or worse.

if youre not sure how your charging system works, seek professional help. when an alternator fails, its usually a good idea to find out why it failed. if you know how to use a multimeter, check battery voltage with motor off&on. motor off should read battery voltage, approx 12-13 volts. with the motor on, you should now read 2 extra volts, approx 14-14.8 regulated volts. if the motor is on and your under 13 volts, most likely your battery or alternator is failing. the pulley on the alternator should have a slight slip with the alternator internals. if the pulley is locked with internals or the pulley is very loose, the alternator needs to be rebuilt. it is recommended to use a new serpentine/drive belt and new battery when replacing the alternator.

belt diagram - goodyear gatorback belts are awesome!


additional tools
pb blaster (if necessary)
2+ ton jack
1+ jack stand
good size crow bar / pry bar
wheel choke / wheel stop

i got an alternator from the yard for $40. i saw rebuilt ones ranging from $175-$250 and new ones $250+. which one you get is upto you, or rebuild the one you have. so the total is $40 + tax + whatever tools or grease you dont have.

getting started
1-disconnect the negative battery terminal or ground.

2-disconnect the positive battery terminal, move it away from the battery. you should look like this.

3-its time to remove the serpentine belt, so if youre small and can get under the car without jacking it up, skip this step. otherwise, stick the choke behind the rear wheel and jack up the car enough for you to work. make sure to use 2 supporting devices, jack and stand, or 2 stands. for the serpentince belt, you should only need to jack up the passenger front side.

4-we need to remove the '2wd' splash guard. there's quite a few bolts and plastic clips. im missing most of them, i dont know how many there are. use a flathead for the clips and 10mm for the bolts.

5-identify which pulley is your auto-tensioner, in picture. it has a 14mm bolt head. to loosen the belt, you need to turn the bolt clockwise, you will see the belt lose tension. NEVER TURN THE TENSIONER COUNTER CLOCKWISE, YOU WILL BREAK IT!!!

6-make sure youve done step 1 and step 2 before continuing. disconnect the ground using a 10mm, unclip the harness with your finger or a flathead screwdriver, and disconnect the red capped cable from the alternator using a 12mm.

7-this is a convenience step, to give us more room to wrench, i moved the coolant reservoir to the driver side, between the motor and intake tubing. i dont know what size bolt is uses, mine was replaced. you should now have some extra room to move the wiring harnesses closer to the relay box/washer fluid. DO NOT BEND THE HIGH PRESSURE A/C LINE, the metal rod with black cap.

· Registered
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Discussion Starter · #2 ·
8-before taking out the 2 mounting bolts, take off the metal tab using a 10mm if its in your way, i didnt have one previously. make sure you use pb blaster if necessary on the long and short 14mm bolts, try not to get pb on your pulleys or belt. make sure both 14mm crack loose before you take them out.

9-before you pull out the alternator, we need to make a little more space. remove the upper radiator support on the passenger side using two 10mm bolts and plastic clip.

10-now pull and wiggle the alternator off, and pull it out. it will fit out kinda like this.

11-you should look like this.

***if youre installing a header or doing some other repair, do it now.

12-now it's time to put in your new/rebuilt alternator. this will be very difficult to line up, but once you wiggle the alternator into place, put the long bolt thru and thread it as much as possible by hand. make sure it's threading! once you have the long bolt in, just swing the alternator up and put in the small bolt. once both bolts are in, torque them down to specifications.

tip - from MoltenNismo - "...a lot of wiggling effort needs to be put in there. A lot of swinging back and forth as well. After you pulled it off, you will see a brass busing on the bottom mount, that is used to sandwich the mount onto the waterpump (where it's mounted). You can use the small bolt with a washer to pull or to "open up" the bottom mount so that when you're installing it back, it'll be a lot easier."

13-clean off the grounding spot on the top mount so you get good contact. bolt in your ground wire using a 10mm. connect the harness, then put the red capped cable onto the alternator using a 12mm, torque it to specs. MAKE SURE THE WIRE GOING TO THE A/C COMPRESSOR STAYS AWAY FROM THE FANS!!!

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2,679 Posts
Discussion Starter · #3 ·
14-the trick i use to do this by myself is to pull the belt off the ac compressor pulley and put it up on the alternator (see step 13 pic). now go below and turn the belt auto-tensioner clockwise while you slip the belt back onto the a/c compressor pulley. make sure the belt is arranged and seated correctly around all the pulleys, see specs and diagram above.

tip: if this is difficult, or the belt is still tight, you could try pushing the belt onto the idler pulley or the auto-tensioner itself. it maybe easier to slide the belt onto a pulley that is not grooved.

...above view

...under car view

15-once you got the belt on correctly, you need to reinstall your '2wd' splash guard that was in the wheel well. on my car, the longer bolts were in the wheel well area and the short bolts were at the bottom bumper/radiator area.

16-now it's time to replace the coolant reservoir back to it's original position. also put the upper radiator support back on, two 10mm and a plastic clip. you should look like this

17-reconnect the positive battery terminal first and make sure its very tight on the battery post. then reconnect the negative battery ground. make sure your battery ground will get good contact.

18-you should be done. double check all of your work, including drive belt orientation. drop the sentra to the ground and fire up the motor and make sure everything is good.

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