GM alternator swap questions

Found one on craigslist. Newish. Looked brand new to me so I bought it. Had the mounting clocking I thought I preferred, not so sure now.
Spent most of the day on install. Turnbuckle was too big so was going to go traditional Mr. Gasket generic arm mount but the water pump bolt snapped right off. Out of desperation I put a hunk of steel between the engine hanger eye and the alt. Nice and tight. Seemed good, took off for work, voltage slowly dropping the whole trip. It's not charging.
Either this alt is no good.
My wiring is wrong.
Belt is too loose.
I got a pig tail that the parts guy said was correct. Big red wire (I put on eye on it and bolted to alt. lug assuming this was the field sensor wire) A brown wire, assumed this was for voltage meter, hooked it up, and black wire, figured it was extra ground, didn't hook it up.
Thoughts?
Alt is off a Cavalier 2.8, 100amp. It doesn't sound good to me either, makes a weird noise once in a while. Maybe it's junk and my penny wise pound foolish side just bit me hard.
Battery is on a charger here at work in the hope it will let me limp home, though my headlights will be on so I don't know if I'll make it. 8 miles.
 
made it home, alt is not putting out voltage. 12.7 ish at alt car off, 12.1 or so when running. Sounds terrible, gets really hot. Should probably pull it and bring it in for testing. It's a CS130 100 amp. I hooked it up with S to + lug and L to the volt line. Did some more research and realized L should be resisted (by idiot light normally) so tried L hooked to resistor for coil, 6v. No difference. There's also a black wire on the pigtail which is P which I left alone. Wow what a nightmare. Maybe I'll just put the Bosch back on while I figure this out. I think this alt is junk but to prove it I need to get it tested and I don't want to drive the car anymore with it in there. It was really hot after a short test run. Ugh. I guess I can put the Bosch back in with a spacer where I hacked the lower pivot mount up.
 
Did some more research and realized L should be resisted (by idiot light normally) so tried L hooked to resistor for coil, 6v. No difference.
Click to expand...
Probably not that great of an idea of two reasons:

1. The series resistor for the coil is small, less than an Ohm. The "L" wire needs something with resistance similar to that of the idiot light.

2. The voltage on coil side of the ballast resistor pulses with the ignition.

Can you use the wire from the idiot light, or is there something missing in that circuit?

found some information on the CS130 alternators here.
 
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ng_randolph said:
Probably not that great of an idea of two reasons:.....
found some information on the CS130 alternators here.
Click to expand...

I was desperate. I decided at midnight to reverse the whole process and put the Bosch back in as I'm 90% sure the cs130 is baked. I will bring it in for testing. I got done at 2, up at 6. This is good for me right?:mad2: I used the spade on the OEM harness to L at first and had nothing, sure the alt was good kept doing silly things. It has to be junk.
 
Ugh, just fired it up and the Bosch unit was supplying good (but flickering) voltage then it stopped and the meter dropped to nothing. Now I thought the volt meter told system voltage, regardless of charging. Battery is up so it should read 12ish no matter what the alternator is doing, yes?
 
I'm very confused and that's not hard to do.
GM alt CS130 100amp
installed
PLFS
S is sensor so I put a ring terminal on it and sent it to the + lug on back of alt.
L is brown and I hooked it to the spade terminal that goes to the idiot light.
No charge, weird noises.
Removed brought to shop, tested fine, twice, putting out 15v.
What am I doing wrong?
Belts appear lined up nicely, tension should be decent. Even if the wire to the starter is iffy, I'd still 15 v at the alt and I don't, just 12.1 which is battery voltage. Now since the Bosch is back in, it only charges for a few seconds then stops. Tranny ground seems fine, secondary cam cover ground seems fine.
What's up??
No suggestions are stupid at this point.
 
Well, I can't see anything wrong with my hook up. I swapped 'em back over and now the new one is pumping out 14.5 volts. No idea what's different. Okay, well. Do I trust this? Only way to know is a test drive, nice long one........:sun:
I'll have to make a bracket yet, my redneck home bracket isn't going to cut it long term.....or the turnbuckle, don't forget the turnbuckle.:mad2:

Long test drive and used it this morning too. Seems alright, bit noisy, will double check belt tension and alignment but otherwise maybe I'm okay after all. Suspsect maybe just maybe, the hook sequence is important, harness first, then lug, or the first try belt was tight/loose/crooked? Weird.
 
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ya man thats pretty much what happened to me when i put on the confirmed good alt for the first time. then i redid pretty much everything without actually taking it off. just loosen and retighten all bolts, terminals and belt and it started to work perfectly.

now im getting a solid 14v driving around. although if im just flying in 4th gear on the freeway for a long time ill notice that over time the needle slowly drops about .3-.5v. however if i turn on something that uses more power(turn signals, headlights, etc) when i turn that off, it comes back up to 14v. a little wierd but no voltage drops to less than 13.5v.

im pretty happy with that now. hope both of our problems have been permanently solved =)
 
I don't get what was wrong but am glad it's working now. I did read it matters the order you hook it up, harness first then lug I think but I always had the neg. off the battery until I was done then reconnected battery so everything went hot at the same time (except me). Mine is still showing slightly weird behavior, voltage is moving around a tad but overall it's fine. Bit concerned with some noise the thing makes occasionally, that and my "custom" bracket is a pathetic.
Yep, we both went on the same adventure at the same time with similar endings. Here's to hop'n they keep working and let us alone now.
 
all seemed well so I installed a turnbuckle instead of the solid bracket I had fabb'd up earlier. Works kinda slick for tightening up the belt. Will monitor closely.
turnbuckledone.jpg
 
Looks good. You definitely want to keep an eye on it. The ends on that turnbuckle are pretty soft steel and may not stand up to the constant vibration and stress. Or it will do just fine and last for years...

It is a nice way to do it. As I recall Bernice did a very nice installation which included a turnbuckle.
 
I'm carrying tools and my old bracket just in case, keep forgetting to put the spare belts on board. There does seem to be quite a lot of vibration, at idle anyway. I put a nut on each end to jam the turnbuckle (one is left handed thread of course) but I'm not convinced it may not turn a bit on it's own, if it seems to, will add a lock washer or loc-tite or something. I do have the Mr. Gasket generic bracket on hand too but the spread between mounting points is only 4" and with my water pump housing bolt sheared off, well, I'll try this first. Also the engine hanger bracket I'm using as the upper mount point is slotted so there is potential for slop there.
 
Well that looks kinda neat Jeff...

When you have the OPPORTUNITY... do remove the parts and annotate as well as photograph them for future reference PLEASE!

Except for the "slotted" issue on the upper bracket you mentioned.... I don't see why this solution should have any more trouble than a conventional bracket. I ADDED similar turnbuckles to my old garage door springs so I could better "fine tune" the balance and they were still good after 20 years of LOTS of stress. Not so much vibration, but lots of stress.

Keep us posted! Good work!

WAIT A MINUTE... that doesn't look like any GM alternator I've seen used lately... Did I miss something?
 
Looks exotic...

What I mean is, this is how the A/C and P/S pumps are tensioned on a late model Lancia Beta. So you're just updating. If the turnbuckle you're using isn't designed for automotive use, it might be made a little sloppy. If you find one from a car, like a Beta, it will be made well.

Any tensioning method is fine as long as you also tighten down the pivot point bolt. Don't leave it loose, or you're guaranteed to have problems. In other words, don't rely on the turnbuckle to maintain the tension all by itself.
 
Black-Tooth said:
WAIT A MINUTE... that doesn't look like any GM alternator I've seen used lately... Did I miss something?
Click to expand...

It's a CS130. Found on many GMs. I think I referred to a bunch of cars that use it earlier in the thread. ('91 Cutlass Supreme 3.4) I went after one of these since the mounting ear is closer to the old Bosch so I thought upper bracket would be a bit easier. 100amps and lo and behold a guy on craigslist had a newish one for $25. The turnbuckle thing was $1.50 (smallest one on the hardware store rack with 2 eyes, many have hooks, first one I bought was too big, only need to cover 4"), left threaded nut to help jam the turnbuckle; .50, all other bolts and washers were gleaned from the OEM set up or found in parts bins or picked up off the garage floor (NEVER sweep your garage).
 
budgetzagato said:
Any tensioning method is fine as long as you also tighten down the pivot point bolt. Don't leave it loose, or you're guaranteed to have problems. In other words, don't rely on the turnbuckle to maintain the tension all by itself.
Click to expand...

I will snug it up some more. All seems nice and operational, steady voltage right in the middle of the dash meter (should probably verify that) it does drop a tad on idle sometimes and sometimes climbs a little higher and it does seem a bit noisy to me. Still optimistically cautious I got a successful swap done for under $30.:jedi:
 
Do you have any pics of the parts from the Beta's? It would be interesting to see if we could use some of the same parts for similar purposes. Not that there are lots of Lancia's to pilfer mind you.

Thanks.
 
turnbuckle to whimpy

Karl nailed it.
Update:
Turnbuckle failure.
First I noticed things were quieter, couldn't hear "something".
Then on highway the "no charge" idiot light flashed, then again, voltage needle low. Crap.
Got home fine and found the turnbuckle bolt had snapped clean off at the jam nut. Too much vibration for it I guess. Maybe some rubber bushings, maybe a "real" one with hiem joints (ouch $$), maybe a "normal" bracket. Maybe there was a just a little too much angle on the turnbuckle, which is easy to fix via washers and such as spacers.
Trouble is with the "closer to stock" mounting point there really isn't room for the long slotted arm, the water pump bolt that most seem to use to mount it snapped off when I went to remove it, so I'm using the engine hanger hole and that is much higher so the angle is too acute for that. The alt isn't big enough for the mount ear to line up with the stock bracket. uh oh. I made another solid bar bracket last night......(early this morning) and took much time to try and insure good belt alignment BUT I had disturbing noises on the ride in. Can't quite figure out what it is but I'm fearful it's a water pump bearing or alt bearing, maybe I put the belt too tight and with solid bracket (not slotted) there's no adjustment. Uh oh. Back to the drawing board, Ugh. Right about now the Bosch is looking pretty good again!
Belt tightness: I could deflect it by pushing on it but it was pretty snug. I'm guessing that an overly tightened belt would over stress the bearings? Another issue is clearance on the pivot end, you can't rotate the alt all that much because it hits the lower bracket mounting bolt heads as it pivots.
 
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Decided to retry turnbuckle, slightly beefier one and this time be sure alignment is spot on. For $3 may as well try it while considering alternatives.
 
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