Swapping out the alternator

TransAmDan

Forum Admin
Staff member
Started the quick job of swapping out the alernator last night. So easy to get to standing underneath it,.
1581587805751.png

Couple of long bolts, and it just comes out.
1581587839667.png
Also the 13mm nut on the back that hold on the power cable. There is also a 4 pin connector with one wire, I guess this is a sence wire. The ground comes through the engine block, and also a braised strap to the chassis.

New one ready to pop in.
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I'll be renewing the power cables too.

Battery is on charge, so that will be nice and fresh. I should get some time on this tonight. No rush as want to run in the new cables and place in a good position. Ideally I want this task of alternator swapping and power cables finished tonight. Incase I need a car tomorrow, as Sarah has borrowed the Kia as the Volvo is in the garage.
 

saleen 192

Core Member
enjoying your mancave then
👍

volve in garage whats wrong ??? apart from the driver lol,,,
 

TransAmDan

Forum Admin
Staff member
enjoying your mancave then
👍

volve in garage whats wrong ??? apart from the driver lol,,,
She could hear squeaking from the rear, like the brakes were binding, got worst as she got nearer work, probably heating up creating more resistance. I drove it to the garage this morning, and I couldn't make it happen as bad as Sarah said, but something isn't right.

Yes enjoying th mancave. So easy to get on and do stuff, the bonnet been up for a couple of weeks, which I have never done before as always having to pack up and make safe over night as it used to sit on the drive. I brought myself some overals too, and I have the rubber gloves, I look like i know what I am doing now.
 

TransAmDan

Forum Admin
Staff member
Factory wiring for the positive side.
battery_connection_a.jpg


I wanted to thicken up the cable, so i have 50mm2 for the starter, and going to run 25mm2 to the alternator/fusebox.

battery_connection_b.jpg

My question is why did Pontiac run a wire from the alternator tot he battery(in black), and run another cable from the fuse box to the battery? Was this method easier/cheaper to do? Or better to smooth out any spike from the alternator before it gets to the sensitive parts of the car like the radio?

My aim is to thicken up the cable, and also install new battery connectors.
The new battery connectors can take 1 x 50mm2, 1 x 25mm2, and 2 x 6mm2. So due to this I need to alter the wiring slightly and daisy chain from the fuse box to bring only one 25mm2 back from the alternator/fusebox.
1581591032022.png
 

saleen 192

Core Member
""" She could hear squeaking from the rear, like the brakes were binding, got worst as she got nearer work, probably heating up creating more resistance. I drove it to the garage this morning, and I couldn't make it happen as bad as Sarah said, but something isn't right. """""

Not going to say a word lol,,,

so the starter motor not fused then considering the amount of current they draw when in use,
if like modern cars they have lots of earth points but is this due to more alloy and differant metals being used older cars more pig iron and eas on running cables, start motor wil be earthed via engine block and is fixed altonator is fixed to some degree but has bolts to allow for belt adjustment, some altonators only have 1 cable (live) as using mountng bolts for earth via engine block bracket,

keep up the good work,
 

AmericanThunder

Super Moderator
My guess is that the fuse box can’t handle the load you propose so they spec smaller wire knowing it would burn out before damaging the fuse box and other components, like the bcm and ecm that are powered from the fusebox.
The daisy chain you propose might be too much for it?
 

TransAmDan

Forum Admin
Staff member
start motor wil be earthed via engine block and is fixed altonator is fixed to some degree but has bolts to allow for belt adjustment, some altonators only have 1 cable (live) as using mountng bolts for earth via engine block bracket,
Yeah on the earth side, I'm putting a 50mm cable from the battery to the block, and also a 25mm from the battery to the chassis.
 

TransAmDan

Forum Admin
Staff member
This is the terminal on the fuse box, connect the alternator to this stud and from that stud connec to the battery. no extra current is passing through the fuse box, just through this stud.
1581594499115.png
Apparently an alternator can supply up to 125Amps, which is more than expected. Good job I'm using cables the same size as what was originally going to the starter motor.

Looking forward to making a nice job of this later. I'll take some photos.
 

saleen 192

Core Member
being a qualified sparks you always want the fuse to blow first never wiring to melt or catch fire the fuse is there for protection , , yep golden rule dan we like photos
 

TransAmDan

Forum Admin
Staff member
There is no fuse between the starter and battery, and no fuse between the alternator and battery. This is original and also confirmed in the manuals that someone hasn't changed it.
 

AmericanThunder

Super Moderator
Then perhaps two runs of smaller gauge wires was cheaper than one daisy chained run of a heavier gauge?
GM are known for using fusible wires, although I’m not aware of anything in a high current situation
 

TransAmDan

Forum Admin
Staff member
Your right, GM have used fusable wires. There are fusable wires around the fuse box area. Not on the high current cables though.
 

saleen 192

Core Member
on mains voltage you have differant curve caritoristics for serge voltages ie air con compressors kicking change from a b type to a c type to allow for inrush current in some cases you have to use type D,

being dc wonder what the surge curve is and for a rewirable(wire sealed (blade ) type fuse is, newer cars have alot more fuses and higher ratings remember the melted one i posted ref my dads van 80amp from memory leave yours as standard if you are happy or if you want to fit a fuse its not a bit thing or hard to do,
 

AmericanThunder

Super Moderator
Ahh, talking of surges I’m wondering if the design is to protect the solid state electronics from surges from the alternator? I know the alternator has rectifiers built in but if that failed it could take out the bcm and the ecm if connected as you propose. Perhaps in those circumstances the battery absorbs it?
I’m no sparky, but there must be a reason why GM did it.
 

TransAmDan

Forum Admin
Staff member
Nice new cable fitted tot he alternator.1581631138320.png

Added the boot too.
1581631376016.png

Nice new battery terminals fitted.
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Also charging,
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TransAmDan

Forum Admin
Staff member
Had to start it to test it the alternator
Great rich idle smell. Soon ran out of breathable air.
 

renchero

Active member
never seen a fuse between the battery and starter motor. but i did fit a fuse between my battery and alternator.
 

TransAmDan

Forum Admin
Staff member
Further to the alternator swap, there was another issue too.
Went to start the car up 9 days ago, totally flat battery, it had been left 8 days. So wasit a duff battery or sometihng pulling current.
Done some current measurements and all looked fine. Charged the battery, left for a day, and then used a voltmeter, only 10.5V, so pointing to a dead cell. Ordered a new battery went to the Optima red top, I had one of these in there like 15 years ago.

Performance Data:
Open Circuit Voltage (fully charged): 12.8 volts
Internal Resistance (fully charged): 0.0030 ohms
Capacity: 50 Ah (C/20)
Reserve Capacity: BCI: 110 minutes
(25 amp discharge, 80°F (26.7°C), to 10.5 volts cut-off)

Power:
CCA (EN -18°C): 815 amps
MCA (BCI 0°C): 1000 amps

Nice to have 1000amps available, and with my thick battery cables, there should be little volt drop to the starter, its going to spin like a sewing machine. lol.
https://www.optimabatteries.com/en-us/redtop-starting-battery/34
OPTIMA_RT_34_Right_copy_copy.jpg

Anyway, this battery is out for delivery today. Hopeing to get it fitted after work, and then nip down to car club in the Trans-Am tonight.
 

TransAmDan

Forum Admin
Staff member
It has arrived
1583246781987.png
 
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