Alternator id

I am embarrassed to say this but how are the Bosch ones identified as per amp rating. Also how about the Denso units. I have been doing this since 74 and never knew.

The bosch units in 240s started at the 55 amp rating and moved up to 65 then 70 and the last version was an 80 amp. They all can interchange. Sometimes you may need to change the upper bracket and connectors but you can put them on any of the ohc redblock.

Denso units are only 80 amp with the small B+ terminal. Then 80 and 100 amp with large B+ terminal. You will have to change the upper bracket and possibly a connector depending on the car but they all interchange as well.

It's really nice to change to the B230F upper adjuster bracket. With the spacer from Volvo and a longer bolt the upper bracket fits all the redblocks and makes alternator belt tension easy to adjust. All the parts are available from Volvo or buy used.

The older B21/23 alternators were also rated, amperage-wise, at an engine speed of 2000 rpm or 4000 rpm alternator speed. The B230 alternators are all rated at 3000 rpm engine speed. Hence why a Bosch 70 amp for a B23F will say N1 14V 70A20, whereas one for a B230F will be N1 14V 31/70A.

The Denso alternators are a much more reliable solution than the older Bosch units are. I highly recommend upgrading to them. One weird thing I've noticed about them, however, when you start the enigne, it'll seem like the warning lights flicker, then go out while cranking. That's normal for the Denso units I've used. I'm guessing it's because they excite more quickly than the Bosch units do.

-J

Thanks for the replies. How are they identified? Are there difference in there appearance? Or markings?

Yeah, they both look different. The denso type has an internal fan and internal regulator. The bosch units are external fan with internal regulator. So the housing looks very different with a stamped steel cover over the back of the denso units.

Thanks for that rpm rating info John. I would also suggest that whatever alternator you use. Be sure it is using one of the higher rated voltage regulators like a 14.4 or even a 14.6 Vsetpoint. That is more compatible to the new batteries in cars now.

If you do a google image search for volvo 240 bosch alternator. Then compare those iimages to a search for volvo 740 or volvo 940 denso alternator. You'll see the difference.

That's not what he is asking. How do you identify a 80A Bosch unit vs. a 100A unit? AFIK, you can't easily if the label is missing. I know my rebuilder can. He probably rebuilds them in his sleep.

It's pretty easy with respect to the old style Bosch 80A and 100A alternators. Same style case, but the 100A alternator is bigger. Big enough to cause unintentional welding when you try to change the oil filter on a B21FT or a B23FT with the 100 amp alternator in the stock lower mounting spot.

The 70 amp alternators, only way to tell without a label is to look at the upper mounting ear. The later one uses a thinner ear that has a square hole for the adjuster's carriage bolt. Earlier one has a thick ear with a round hole. B230 adjuster goes on the front side of the ear, whereas the B21/23 adjuster is on the rear side of the ear.

I have a 100a denso forsale

Then of course there is the 100 amp bosch unit that is Denso type design but is huge. Probably weighs more than a turbo. lol. These are on the later model 940 cars like a 93-95 if i recall correctly. they are internal fan/ internal regulator like a denso with a large black plastic back cover.

Bingo !! Now I can sort thru the pile . The only Denso I had got installed on a one owner 1948 Plymouth.