• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

GM Alternator Swap

my gm 100 amp doesnt charge much better then my 200k miles volvo 100 amp. is a 10 gauge ground too small?

oh and holtzboy you may need a smaller pulley for the alt. the serpentine belt pulley that came with my gm alt was a lot smaller then the standard volvo pulley
 
n xntrx volvo said:
fyi, b21/b23 based pentas are set up for a gm alt factory. just grab the bracket like i did.
Click to expand...

Where did you get it and how much did you pay?
All the places I've contacted want $50 or more for this simple piece of metal...

JD
 
Well I just did the alternator swap on my 144. It was neccessitated by my sound system which was drawing ~25-30A from my 35A which meant that at night I would be flattening the battery and triggering warning lights if the headlights were on.

A couple of things were different:
-I live in Australia so rather than a GM alt I used a Bosch Alt (From a TR-ish Magna). Still it is an 85A unit as compared to my oem 35A.
-I didn't need to fabricate a bracket.
-I did need to change the pulley on the new alt to a V belt.

Mounting was fairly straightforeward I was able to use the stock mounts with no problems. The only thing I needed to do was fab up some spacers for the lower mount.

Wiring was also pretty straightforeward. I upgraded the current wire (some 8 gauge) and connected the starter to the alt B+ as the old one had been. This left two wires on the alt, labelled S and L respectively. Took an educated guess that S was signal eg ignition and L was light eg warning light. Connected L to the existing wire. Perused wiring diagrams to find an appropriate location for S to be drawn from. The coil looked a good place, fitted a two way adapter to it and connected to S. Pretty straightforeward.

The only hassles were:
-The new alt is physically larger (dah) and so wouldnt swing in toward the block as far making putting the belt back on abit tricky.
-Had to pull the fuel-pump to get the lower bolt in.

Total cost was $40 (AUD).

EDIT: Oh I also ditched the oem voltage regulator as surplus to requirements.
 
Last edited:
In my experience with the GM alt, i found it to be only this - much better then the volvo 100 amp alternator, Granted its smaller, i found mine to have unussual spikes and drops and the amount of work to propperly shim it and grinding to make it fit was just not worth it in the end.

I am currently moving the alternator to the space that the ac compressor was in. this will move it away from the heat, shorten the wires, and provide more clearance on the turbo side. (this is from a 240 owner point of view)
 
Personally a GM alternator isn't a good idea. They're notorious for failing at an early age. Better off sticking with an improved Volvo unit or Denso. I've seen 100 amp Volvo units anyways, and lord knows the Japanese know their way around electronics.
 
bumpbox said:
Personally a GM alternator isn't a good idea. They're notorious for failing at an early age. Better off sticking with an improved Volvo unit or Denso. I've seen 100 amp Volvo units anyways, and lord knows the Japanese know their way around electronics.
Click to expand...

well one of the plus's was the size/weight/cost compared to the volvo unit, but your right about the gm unit failing early.

Im interested in this Ford unit people are talking about now.

~Kyle
 
Ford would be a better choice. I guess now it's technically OEM for Volvo. Motorcraft tends to have good electrical stuff. I have a sneaking suspicion that the Motorcraft units might be Denso. Afterall, Yamaha builds most of their engines. The V8's anyways. Mazda builds their 4's and V6's.
 
bumpbox said:
Ford would be a better choice. I guess now it's technically OEM for Volvo. Motorcraft tends to have good electrical stuff. I have a sneaking suspicion that the Motorcraft units might be Denso. Afterall, Yamaha builds most of their engines. The V8's anyways. Mazda builds their 4's and V6's.
Click to expand...

FWIW, Yamaha has only built one and only one V8 for Ford: the 3.4L in the '96-99 Taurus SHO. This engine was never used in any other vehicle.

Yamaha has built one and only one V8 for Volvo: the new 4.4L in the XC90 and 2nd gen S80. This engine is not used in any Ford vehicle.

Ford builds its own V8s, V6s and inline 4s itself in its own engine plants in the U.S., with the exception of only a scant few smaller engines that are made in conjunction with Mazda and only for the vehicles platforms that were co-developed by Ford and Mazda.

What this all means is that Volvo still operates as an independent entity within Ford. '99+ Volvos still to this day do not run Ford parts and one still can't buy Volvo parts at any Ford dealer and vice versa.

That all said, it's worth noting that many Ford engines, especially Ford's own large displacement modular engine family which are generally fitted with the highest amp alternators available bolt directly to the engine block or to the intake manifold without a bracket at all making retrofitting onto a non-Ford engine a bit cumbersome.

As far as Ford's Motorcraft service parts go, there are *many* OEMs like Denso, Bosch, etc. that produce service parts for Ford under the Motorcraft brand name. Ford does not produce the majority of its Motorcraft service parts itself. So the case of alternator retrofitting, the OEM of a Motorcraft alternator will vary by the alternator part number and the engine the alternator is designed to fit.
 
volvoid said:
FWIW, .

What this all means is that Volvo still operates as an independent entity within Ford. '99+ Volvos still to this day do not run Ford parts and one still can't buy Volvo parts at any Ford dealer and vice versa.
.
Click to expand...

Soryy to bust your bubble on this one. 99 to about 04 you are correct Starting with the 04.5 s40 Volvo has been using Ford parts and the newer units late 06 an 07 have FOMOCO stamped all over them.:-(
 
I just put a 87 Tarus 4cyl alternator on mine. It fits like factory. My orginal alt died, and this was the cheapest alt availible in town. No Volvo units anywhere. But, Im still not charging. Its bull****, I wired everything upcorrectly, and Im still not getting a charge. WTF? 12.2 volts FTL
 
Top_ntocH 740GL said:
I just put a 87 Tarus 4cyl alternator on mine. It fits like factory. My orginal alt died, and this was the cheapest alt availible in town. No Volvo units anywhere. But, Im still not charging. Its bull****, I wired everything upcorrectly, and Im still not getting a charge. WTF? 12.2 volts FTL
Click to expand...

OK, found a scematic. going to redo wiring now... :embarrassed:

For all interested, I found a .pdf on a bronco forum with the schematics for Ford's 3 G alternators. They are availble in 65, 100 and higher amp ratings. The one I used, the 87 Ford Tarus 4 banger, bolted right in like factory. No modifications, minus wiring.
 
I made the mistake of getting a Duralast alternator in my 90 245. BUT they did have a lifetime warranty, i was in auto zone every month or so for a new alternator.
 
Jeh said:
Soryy to bust your bubble on this one. 99 to about 04 you are correct Starting with the 04.5 s40 Volvo has been using Ford parts and the newer units late 06 an 07 have FOMOCO stamped all over them.:-(
Click to expand...

Quoted for truth, and add the statement that all FOMOCO parts are stocked under ford partnumbers...
 
nope i havent.. i think the gm would be a better bet to try since there is an article up i jut wish there were pictures included in the article.
 
If I have the time to look into it I want to see if the spare 90A Ford 3G will work on my '85 240. I kind of glanced at it when I was working on some front susp stuff and had the splash pan out of the way. Not sure what stock is on the car but I plan on wiring up fogs and adding an e-fan in the future.
I need to dig up some wiring diagrams for my car...
 
So I am going to talk to a master mechanic i just et about making a bracket if its needed for a high output iceberg alternator or an old ford.. If the bracket is required I am gonna have this guy make a bunch for me so I can get them to you guys. This is gonna take a few days to make sure this can happen but believe me it will.
 
You must log in or register to reply here.
Back
Top