| Author | Message | ||
     Chris Miller Grand Master Username: cjm51213 Post Number: 409 Registered: 5-2013 |
Hi Folks, I have suspected for some time that my alternator was not up to snuff and this morning, on a whim, I stopped into Napa and they confirmed my suspicion. I don't think it is completely dead, but I think it is only generating about 12 volts, where it should be generating 15-ish. So, this raises some questions. Is this a GM alternator, maybe with a contemporary part number? Does anybody have an application cross-reference for a contemporary alternator? Is there any advice available for rebuilding an alternator? If the bearings are still good, and I suspect that they are, it is brushes and diodes, but that raises the issue of parts. Anybody have any leads? Brian: I looked through my copy of your Resources guide before I asked the question, so I am trainable. (-: Chris. | ||
| Bob Reynolds Grand Master Username: bobreynolds Post Number: 404 Registered: 8-2012 |
It might not be the alternator, it might be the control box. This adjusts the output voltage from the alternator with respect to electrical load, battery voltage, etc. Bob UK is the expert on this, as he always used to be on about adjusting the output voltage. You might find some useful information in his posts. | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 410 Registered: 5-2013 |
Hi Bob, Where do I find the control box? It seems to be worth investigating... Thanks for the help, Chris. | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 122 Registered: 7-2012 |
Chassis no. would help, but control box usually CAV aluminium in colour standing vertically bolted in front of o/s heater blower motor under bonnet(hood) | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 456 Registered: 5-2007 |
Located on the right side bulkhead, as Gordon says, near the blower motor.   | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 457 Registered: 5-2007 |
These are not hard to find. Shop around - some online stores charge much more than others. Take a photo of your one to get an exact match. This is a part I recommend everyone keep as a spare in the boot. It is, for our cars, an unusually quick plug and play fix if it fails. | ||
| David Gore Moderator Username: david_gore Post Number: 2086 Registered: 4-2003 |
Chris, the alternator on DRH14434 was a CAV heavy duty alternator. Any auto electrician should be able to rebuild whatever alternator is fitted to your vehicle. If the regulator is faulty, replacement clones of the original Lucas unit are available. | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 411 Registered: 5-2013 |
Hi Jeff, I suspected that was the part. I can hear it click when I press the horn button. Is it adjustable or simply replaceable? How do I test this thing? It may be the problem or it might be good and the alternator is the problem. Is this a GM or Lucus alternator? Thanks for the help, Chris. | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 412 Registered: 5-2013 |
So, this is twice I've encountered "CAV" and I don't know what it means. Or at least I don't recognize it. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 271 Registered: 4-2016 |
According to the net CAV was an electrical pioneering company formed by Charles Anthony Vandervell. Many firsts were achieved by this company, so it seems Lucas saw the value in it to further their needs so Lucas purchased CAV in 1926 https://en.wikipedia.org/wiki/Lucas_Industries#CAV Very interesting reading not just about CAV, but Lucas as well. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 272 Registered: 4-2016 |
Wish my engine bay looked like that Jeff. I somehow need to clean mine before the next Concours as it was noted as being "a bit dirty" at the last one. But a LONG time car and truck mechanic here in Oz, all of our old cars and trucks were Lucas equipped and I know never to mix Lucas with water. But I am really struggling to know what to do here. Anyway. Awesome engine bay mate. | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 458 Registered: 5-2007 |
Ah Patrick, if only it were mine! I collect photos of parts and details of our cars for reference purposes. I've currently got a flooded carburettor and a report of the dreaded sludge leaking from my rocker cover - detailing my engine bay is on the list, but nowhere near the top of it yet... | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 274 Registered: 4-2016 |
If you weren't so far away Jeff we could get together for a good clean! Bugger, I hope you can sort it out soon mate. | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 413 Registered: 5-2013 |
Hi Folks, So the brand is probably CAV. That helps. I'll look for marks and see if I can determine the model. I still don't know how to determine if my problem is the voltage regulator or the alternator proper. Is there a diagnostic to tell me? Assuming it is the voltage regulator, is the voltage regulator something I can repair or is it only replaceable, like a light bulb? Is there a specification, like an electrical diagram of this thing, so I know how it works, if I have to consider a contemporary replacement? Assuming it is the alternator proper, the parts in question are the brushes and the diodes. Does anybody have a source for brushes and diodes? Thanks for the help, Chris. | ||
| Omar M. Shams Grand Master Username: omar Post Number: 703 Registered: 4-2009 |
The chances are much higher that your problem is the regulator box and not the alternator. | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 414 Registered: 5-2013 |
Hi Omar, I am inclined to agree, but I sure would like a dispositive test. For example, can I measure the voltage at the alternator if it is completely disconnected, meaning is the regulator necessary for the alternator to function in any capacity, or is it simply a mechanism to shut the alternator off to prevent engine drains? I think this divides my problem. Either I am getting acceptable voltage at the alternator, or I am not. What would be the expected voltage reading at the alternator terminals? There is the concomitant problem that I may not be producing enough juice to maintain that voltage in the face of existing demands, but if I can measure volts at the alternator terminals, I should be able to measure amps. So, what would be the expected reading for amps at the alternator terminals? Thanks for the help, Chris. | ||
| Jean-christophe Jost Experienced User Username: jc_jost Post Number: 21 Registered: 3-2016 |
Chris, I think this thread is a reference http://au.rrforums.net/forum/messages/17001/16889.html and there is also a diagam of the regulator in Tee One Topics issue 51. Best regards | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1295 Registered: 5-2012 |
Chris Can't you get a free test at one of your local motor factors like Autozone, O'reillys or Pep-boys. I've just picked this up off Google: "AutoZone will test your car's parts for free. We can test your car's battery, alternator, starter and voltage regulator while they're still on your car. We can also give your car a complete starting and charging systems test." Geoff | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 262 Registered: 10-2010 |
The regulator is needed for the alternator to function at all. It controls the current in the rotor field, which in turn controls the output voltage. But yeah, it should be pretty easy to get it tested.... Cheers, Jeff. | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 88 Registered: 1-2014 |
There is a symptom that helps diagnose alternator problems. If you hear a high pitch whine (fairly faint but audible) in your radio speakers (when the radio is on) that corresponds to engine RPM's it is symptomatic of a bad diode in the alternator. You can easily test whether the alternator or voltage regulator is faulty by following the instructions on page M25 & 26 here: http://rrtechnical.info/sy/tsd2476/13.pdf Parts for these should be available at any automotive electrical rebuilder. SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 415 Registered: 5-2013 |
@Jean-christophe: Thanks for the reference. That is quite helpful. @Geoff: I can get a test and I did, but the test is binary -- "Works" or "Doesn't work". My test showed "doesn't work", but my experience show that it mostly works. And the test doesn't explain what is wrong, meaning regulator, alternator diodes, alternator brushes, or anything else that I might not understand. @Jim Walters: I've been reading that section. And each time I read it I understand better what I should do. I understand more now than I did last week partly because everyone has been so helpful with my education. The regulator is non-serviceable so I think I have a line on a replacement. I will probably want that even if the one I have is fine. I like to have spares. Swapping the regulator is a pretty easy diagnostic, assuming the new one is working correctly, and with the Tee One topic issue 51 diagram, I should be able to perform some minimal integrity tests. Thanks for the help, Chris. | ||
| John Kilkenny Prolific User Username: john_kilkenny Post Number: 242 Registered: 6-2005 |
Chris, There are three unknowns in this equation, the alternator, the CAV voltage control and the battery. Any one can be the problem. Firstly the voltage control. If the ignition light comes on when the ignition is switched on and goes out when the engine starts it is unlikely the control is faulty. There are three control inputs marked H (High), M (Medium) and L (Low) corresponding to the expected load on the battery. These affect the alternator voltage output. See which one is selected. For a quick check of the alternator, with the engine on fast idle, switch on the headlights and check the voltage at the battery positive terminal with a voltmeter. If it's over 13.5 it's probably OK. Finally the battery, how old is it ? Does it hold a charge when the car is not used for a couple of weeks ? Maybe it's time for a new one. |
