Volvo 940 not charging

[TonyS9]

Buying alternator overhaul kits is not a regular thing here. You should be able to change the regulator and / or brushes, but bearings and other problems can be more tricky.

Usually an auto electrical refurbisher/repairer can do this fairly cheaply if you bring your part to them.

[Laird Scooby]

Originally Posted by taiwan740

Yup, perhaps the alternator body isn't grounded after all, or I just got a crap ground when I did the test.

When I connect the small red wire, battery light and everything else works fine and it charges. Disconnected, it gets the same symptoms as before with the bad alternator.

I wonder if that ring connector on that cable was just a bit cruddy or something. I will bench test the old alternator somehow or something I guess.

The alternator body should have a strap to connect it to the engine block to provide an earth path as the alternator is mounted with rubber bushes so is isolated from the engine.

Like Tony says, it's not the usual things to buy alternator rebuild kits here. Several reasons, you need specialist tools/kit for dismantling/rebuilding and also testing - NO YOU CAN NOT DO IT ALL WITH A MULTIMETER!

Also the cost of the rebuild kits works out nearly as expensive as a reconditionied unit which comes with a guarantee. Which would you choose - a rebuild kit to do it yourself and have no guarantee or pay a little more and get one already done with a warranty?

Also to find a rebuild kit, you'll need the Bosch part number, usually starts with " 0 120" and is 10 digits in total. The Volvo part number isn't a great deal of use sadly, Volvo (in common with many other manufacturers) applied their own part numbers to units that met the specification they wanted. With some car manufacturers, the same part number was used regardless of the original manufacturers! For example, a Ford alternator might have a particular part number but could have been made by Motorola, AC Delco, Lucas, Bosch, Marelli, Magnetti-Marelli or FoMoCo.

The Ford example is an extreme but others used 2 or 3 different manufacturers but with the same part number for the customer.

[Derek UK]

This comment a bit late in the day, but is there any similarity with the fault that you can get with 240's where the connection wires go down under the engine below the front pulley? Loom can get oily, damaged, and touch things under there. Perhaps that issue was fixed with the 940.

[taiwan740]

Originally Posted by Laird Scooby

The alternator body should have a strap to connect it to the engine block to provide an earth path as the alternator is mounted with rubber bushes so is isolated from the engine.

Like Tony says, it's not the usual things to buy alternator rebuild kits here. Several reasons, you need specialist tools/kit for dismantling/rebuilding and also testing - NO YOU CAN NOT DO IT ALL WITH A MULTIMETER!

Also the cost of the rebuild kits works out nearly as expensive as a reconditionied unit which comes with a guarantee. Which would you choose - a rebuild kit to do it yourself and have no guarantee or pay a little more and get one already done with a warranty?

Yeah I agree with what you're saying, but I'd like to give it a go as a project. I also have an electronics lab at my disposal =D I've got the bosch number as well of course. I've ordered a reconditioned unit which is a few weeks off but is now working on a cheapie scrapper unit i got off ebay just so i have wheels again.

Yes it has the grounding strap onto a bolt, i should have really connected it to this but it was windy and started raining and generally I lost interest haha

So if you had a working alternator, and a reconditioned unit with a guarantee, and a non-working alternator, then why not crack the broken one open and give it a good ol' whirl? Learn by doing!

No idea about the 240 sorry.

[Laird Scooby]

If you have an electronics lab at your disposal, first thing to point out is that although you can get a basic test on the rectifier with a multimeter, you need to load them up to test them. A 21W bulb is usually sufficient and then reverse the polarity to get the go/no-go operation of all 6 rectifier diodes. Also check the diode "trio"that feeds from the outputs of the stator to the voltage regulator. For the voltage reg, you will need a dedicated voltage regulator tester - not cheap and unless your electronics lab is an autoelectronics lab, highly unlikely you'll have one floating around!

You'll also need a 100+W soldering iron to desolder the rectifier from the stator windings and also the slip rings from the rotor windings. You also need to measure the distance from the nearest slip ring conductor to the back of the rotor as they vary and when the new one is fitted, you'll need epoxy resin adhesive to secure it in place.
There are also 2 different diameters of slip ring applicable to Bosch alternators of this age, 28mm and 32 mm, the voltage regulator is different on both as well not ot mention slight other differences but generally there are two main voltage regs fitted to the Bosch alternators from this time.
The brushes come with the voltage reg, it's not worth trying to renew just brushes as the regs tend to fail soon after the brushes have worn out.

Then you'll need bearing pullers and a press of some description to remove and refit the bearings and slip rings. Also take photos as you strip it down, there are some spacers and washers, particularly on the Drive End that need to be kept in order for the pulley to run in the right place. From memory, you need an 8mm Allen key and 22mm cranked ring spanner to unbolt the pulley.

That should get you started, i could never remember the bearing numbers on the Boschbut 6302ZZ rings a bell somehow.

[martin calva]

Originally Posted by taiwan740

Hello

Drove to work this morning to notice the battery light very faintly on at idle. Immediately thought alternator. Went out at lunchtime with multimeter, checked battery voltage at 11.9V (i left the sidelights on which didn't help) with car not running, and 11.3V with car running. So not charging, fair enough. No cables flapping about and the alternator was going round as well. Battery is not old.

So its the alternator, fine, easy.

But is it?

When I turn the key on (not engine) I get only the lambda light, handbrake and oil light (intermittent fault on this one). No battery light at all. Red flag?

My main concern is that the car does have a problem when its been sitting in the rain for days that the speedo, oil light and odometer either don't work for days or go loopy, I assume due to moisture. Could it be that the battery light has gotten damp as well and therefore the alternator isn't activating?

I have a spare instrument cluster in the parts bin but no alternator. Should I just change the alternator and shut the hell up, or is that battery light thing weird?

For those interested, Its a B230F 940 GLE MK1 automatic with about 210,000 miles on it. Had it for two years just this week, saved from scrap.

cheers

Excuse me it this has already been suggested but if a 940 is not charging, it may simply be that the alternator's regulator needs replacing. If the rev counter has stopped working that is a confirmation. They are available cheaply on Ebay and are held in place by two screws, easily accessible.

(In contrast, to change the regulator on my 1998 V90 is a morning - at least - of intensive knuckle skinning work.)

[Laird Scooby]

Originally Posted by martin calva

Excuse me it this has already been suggested but if a 940 is not charging, it may simply be that the alternator's regulator needs replacing. If the rev counter has stopped working that is a confirmation. They are available cheaply on Ebay and are held in place by two screws, easily accessible.

(In contrast, to change the regulator on my 1998 V90 is a morning - at least - of intensive knuckle skinning work.)

Just to give you a condensed version of the thread Martin, Ash and i both suggested the time-honoured test of grounding the warning light wire to test the bulb operation - in fact Ash beat me to it as he obviously checked for new posts before i did that day!

Anyway, the OP tried it, got inconclusive results and simply changed the alternator and now has a working warning light and alternator.

As such, we may never know the exact cause.

However he would have had a working rev counter as his is a petrol model and takes the signal for the tacho from the correct place, i.e. the -ve terminal of the coil, not a tapping on one of the alternator stator windings, usually marked "W" on the back of the alternator as the diseasels need because there is no spark ignition.

[940volvoman]

Voltage regulator ??


Shaun

[Laird Scooby]

Originally Posted by 940volvoman

Voltage regulator ??


Shaun

Have a look at my post above yours Shaun and the one above that!