Hi guys,
I put a 240 alternator with integrated VR in my 122, and everything worked well for several months, but now it won't charge. What I find puzzling is that the amp light no longer comes on in any circumstance, even with the ignition in the 2 position before starting the engine. I've tested the bulb and it's fine. Any thoughts?
Is the D+ terminal supposed to switch to ground when it doesn't charge, in order to light that bulb? Thanks!
Rob

In the spring, I check my regulator - I look for signs of damage to the internal parts and for any issues with the contact points.

I also observe it when I turn on all the electrical equipment and rev the engine.

When my 3-year old had several ear aches, I asked her doctor if I should but one of the lights he used to check her ears - he told me that I would not recognize an ear ache - I assured him that I would be able to see an ear ache if I looked in her ears every day or two when she was healthy!

Even if I do not know what I am seeing each spring - I will see if anything changes.

James;

I didn't know at first where you were going with the child's ear analogy, so I was intrigued and read it to the end...
"Even if I do not know what I am seeing each spring - I will see if anything changes."...OK, so your point is to know the normal baseline, and then you'll be able to recognize any abnormality...I understand and agree...the Bosch Gen/VReg based Chg Sys is highly reliable as it is based on sensing currents and magnetism, unfortunately neither of these can be seen unaided...so to help with having something more than just a visual baseline, I would suggest connecting a Digital Voltmeter to the terminals of the VReg while performing your tests (measuring Currents with clamp-on current probes is left for the experts!), to associate VReg action with voltages, as ALL operation will be affected by the (Battery) buss voltage (which determines currents through the sensing coils of the VReg)...don't forget, the Gen/Vreg combination is controlled by currents and their resulting magnetic action in the VReg.

Explanation of what all this technical mumbo-jumbo means here: https://www.sw-em.com/Bosch%20Generator%20based%20Ch%20Sys%20in%20Detail.htm

Cheers

I have a B20. I think the mount is the same. A couple of us used an alternator from the PRV V6 240. You just drill out the bottom mount hole to a half inch and add a 10MM spacer on the bottom. I got mine from rock auto. It wasn't expensive. The pulleys lined up fine. Hope this helps.

I found a spare voltage regulator to try, and it worked! Now it charges and the amp light works again. Thanks all of you for your helpful input! Much appreciated!

Rob

I found a spare voltage regulator to try, and it worked! Now it charges and the amp light works again. Thanks all of you for your helpful input! Much appreciated!

Rob

Is the alternator making any strange noises? A bad diode will cause them to make a "growling" noise. Are the bearings still good? I've seen bearings get so bad that the rotor will start hitting the stator & completely destroy the alternator.

No noises whatsoever, thankfully. I wouldn't expect there to be on such a new alternator, but stranger things have happened...
Rob

How have you mounted the alternator? I know it has been working for you but the alternator needs to be earthed to the block. The rubber-mounted dynamo bracket should be used unless you take the rubber isolators out. You can use a jump lead between the alternator body and a good ground to check if this is a problem. Obviously, you have checked all of the wiring for continuity? Easy to miss a dodgy connection.

Used or rebuilt alternator?
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Hi Eric, it's a used Volvo original unit with about 15000 miles on it from new. I rescued it a few years ago from my father's 240 before we sent it to scrap.

Rob

15 thousand or 150 thousand miles?

When rebuilt by Bosch, a new voltage regulator with new brushes would have been installed.

If the brushes are worn badly enough, the alternator won't charge.

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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

15 thousand. That's why I rescued it when the car was scrapped. The alternator and regulator were brand new from the Volvo dealer. If the regulator and or alternator are toast, it would be strange but possible. What I can't understand is why my amp light doesn't come on at any time. I'm wondering if that might be why the alternator is not charging. Would this type of alternator require that amp light to function in order to kickstart the alternator?
Thanks!

Rob

Rob;

In the Delco based Charging System, the Amp Indicator supplies Field initially from Battery, until the Alt starts making power, extinguishes the AMP Ind (no voltage across!), and it takes a little of that output power to supply Field.

I expect the Bosch (with integral VReg) based Chg Sys is similar, but I know in the early ones, with separate Alt and VReg, there were variations (see: https://sw-em.com/123GT_Charging_System_Notes.htm#1800E_ES_Charging_System_Notes )

An effective troubleshooting trick is to divide and conquer...as in separate the Alt from the VReg, and manually supply the Field, thereby taking the VReg out of the picture...if Alt then makes power, VReg is suspect...if Alt does not make power, IT is suspect...

...if you post a wiring diagram of the Bosch based sys (including internals of the Alt (with internal VReg) I'll have a look at it, and try to give some troubleshooting suggestions...

Of course, it should be said to check the easy stuff first...like Fanbelt tension, connection of Field power to Alt, general wiring associated with Alt, Brush wear (yes I read Alt wasn't very old, but again, its worth checking the simple stuff first)...

Good Hunting!