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Author Topic: 1987 Silverado 4x4 - Help identify alternator?  (Read 7222 times)

Offline Mike Phillips

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1987 Silverado 4x4 - Help identify alternator?
« on: September 17, 2014, 07:15:40 pm »
1987 Silverado 4x4 - Help identify alternator?


Battery started dieing on me and since I wanted to replace it anyways I installed a new Interstate Battery.

Now batter won't stay charged up.  Took truck to local NAPA and counterman tested and said alternator was bad.

Went inside store tried to look up the correct replacement and everything shown for my truck had the V-Groove Pulley.  The alternator on my truck has the serpentine style belt.

Called the previous owner and he wasn't sure if the motor they installed was a few years earlier or same year?

Was thinking if I posted some pictures one of you guys would recognize the alternator and let me know what to order.








Can also take the one on the truck to a local shop and have it rebuilt but was trying to do the repair in one session.

Mike
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Offline bd

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #1 on: September 17, 2014, 07:29:37 pm »
The premium output 93-amp 12SI series with 5-rib pulley is pretty standard for the 1987 TBI engines. 

Needs a belt, too!   :o
« Last Edit: May 02, 2024, 01:55:46 pm by bd »
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Rich
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Offline Edemich

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #2 on: September 19, 2014, 08:48:51 am »
Just swap your pulley onto the new alternator!  It's pretty straightforward. 
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Offline Engineer

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #3 on: September 19, 2014, 05:20:44 pm »
That is a Delco 12SI alternator. If everything else is the same just swap the pulley. 15/16" socket and impact wrench.
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Offline Irish_Alley

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #4 on: September 19, 2014, 11:20:18 pm »
had the same problem with my 86. ended up swapping pulleys you also need to swap the fan the plastic one that you have now is newer and better for the alt but once you take it off you will see there's a lip around the alternator increase air flow the new fan on old style wont work as good but its not something that will kill the alt anytime soon. never had a problem with mine
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Offline bd

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #5 on: September 20, 2014, 09:55:28 am »
As stated, swapping pulleys is common practice if you have an impact wrench.  But, you need to be observant when doing so, because not all fan/pulley configurations use the same spacer - some spacers are taller than others and mismatching parts can distort the fan or even bind the rotor.  If there is a parts mismatch, it will become apparent as you tighten the nut.
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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Mike Phillips

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #6 on: September 23, 2014, 03:41:50 pm »
Hey thanks for all the replies guys....

My goal was to do a straight rip out and replace.  Time and a shop I can tear down in are a rare commodity now days.

If I can go down to Autozone tonight, pick the one up listed in this thread, bolt it in and adjust the fan belt that would work best.

We'll see what happens....

:)
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Offline frotosride

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #7 on: September 23, 2014, 07:50:32 pm »
Just a trained eye's observation.... Your voltage sensing wire connection looks like it has seen a little heat. Check your fan and check for grounds. It is heating up and may have burned out because you have a serious problem. Please don't over look this because electrical fires happen before you realize it.
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Offline jetmech

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #8 on: September 24, 2014, 12:17:29 am »
It has been a few years since I bought one but Autozone used to change pulleys for you free and on the spot.
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Offline Irish_Alley

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #9 on: September 24, 2014, 09:54:03 am »
When I worked there we would have a electric impact and sockets by the table vise near the "testing station" still today if I want I'll still go back there and do things. Some customers still think I work there even after 8 years after I quit. 
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Offline Mike Phillips

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #10 on: September 25, 2014, 08:51:15 am »
Quote from: frotosride on September 23, 2014, 07:50:32 pm
Just a trained eye's observation.... Your voltage sensing wire connection looks like it has seen a little heat. Check your fan and check for grounds. It is heating up and may have burned out because you have a serious problem. Please don't over look this because electrical fires happen before you realize it.

Thanks for the heads-up... I'll examine and clean the plug when I install the new alternator.  I picked one up at Autozone last night but won't have time to install it till the weekend after this weekend as I'm teaching a detailing boot camp class this Saturday and Sunday and have to prep for it with 5-6 different cars coming in for the class.

:)
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Offline Mike Phillips

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #11 on: September 25, 2014, 08:53:40 am »
On the AGO forum I made a joke about using this guy's Fiat for a spare tire...





:)

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Offline Edemich

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Re: 1987 Silverado 4x4 - Help identify alternator?
« Reply #12 on: September 26, 2014, 09:13:06 pm »
Is that your truck? Sweet! What size lift is that? Rims and Tire size too? I am looking for ideas.
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Dark Ming Blue 85' K10 w/355 SBC, Edelbrock top end kit with Scorpion Roller Rockers, 2001 14B FF w/4.56 gears, NV4500 5spd, One Piece Rear and Door Glass
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