stumped...engine charging...or not

[6969ronin6969]

Here's the history, I noticed my ammeter was reading negative one morning with the lights on. I figured the generator had finally given up, but took a look at the regulator first before pulling the generator out and having it rebuilt. While looking at the regulator I tried cleaning the contact points and adjusting the gaps to what I saw in the manual. That didn't fix it, so I went ahead and pulled the generator. After I got it back and installed I put it in and everything seemed good. Possibly too good as now the positive charge I could see on my ammeter was pretty high. I felt the need to turn on my lights just to keep from overcharging the battery. The next morning I came out and the battery was drained. My son (4) had been sitting in the car the day before so I figured he had left somethig on. I recharged the battery with a charger and drove to work the next morning. It was early so I use my headlights. With that situation the ammeter still showed a slight charging situation. When I cam out of the office in the afternoon, my battery was drained. This happened 2 days in a row. I thought the battery might be bad after getting discharged earlier so I took it back and got another one(was still in the replacement phase). Well, the next morning, the car was dead again. Until I the generator went I never had a discharging issue. I could let the car sit for a couple of weeks and comeout and she'd fire right up. The only other thing I had messed with in the system was the regulator. So I went back to that and started double checking my earlier adjustments. I could see where one of the contact points was touching, when cold, and adjusted this based on another period Lucas manual I came across that was specific to the regulators from this era. After sitting overnight the battery was not drained so that seemed to have fixed that problem. However now I don't appear to be charging the battery either. Could I have damaged soemthing based on the explination above? If I put a voltmeter on the battery while the car is running and rev the engine the meter does hold a steady reading of about 12.70V and seems to uptick to 12.71V if I wait a couple of seconds while revving the engine up to 2k rpm or so, but I would expect it to read higher, plus my ammeter never goes positive now, but it will read negative if I turn the lights on. Any ideas?

Thanks,

Eric

 

[Mickey Richaud]

Hi, Eric -

Not sure if it's relevant, but many electrical problems turn out to be ground issues. Be sure ALL ground connections are good - especially the strap from the engine to the frame.

Hope this helps, and keep us posted.

Mickey

 

[6969ronin6969]

Will do. On that note, how securely does the regulator need to be mounted (does the mounting act as a ground)? I ask becuase when I first looked at the thing I un screwed it so that I could see better and more easily clean it up. At that time one of the threaded retaining plates fell out and I now just have it mounted by the 1 remaining screw.

Thanks,

Eric

 

[Mickey Richaud]

According to this wiring diagram , there's a dedicated post for grounding. Click on the magnifying icon, and you can zoom in.

 

[TR3driver]

IMO, you've messed up the regulator. It doesn't need to be mounted at all, since the case is plastic it only grounds through the ground terminal.

Here is a Lucas document that addresses testing of both control box and generator, plus control box adjustment. (You should have a RB106/2 control box, so ignore parts 3 and 4)
https://docs.google.com/viewer?a=v&p...Fm&hl=en_US

 

[6969ronin6969]

Randall,

I think you are correct. I took the generator back to the rebuild shop along with the regulator. They supposedly checked everything and said the regulator was bad. They rebuilt the generator again, not 100% sure, but something about the solder being melted. I ordered a new regulator from TRF and installed everything.

I fired it up and it looked good. The charge on the ammeter went up and down from idle to higher revs (the battery ahd been discharged some from me repeatedly starting it while diagnosing things). I ran it for maybe a couple of minutes and shut her down.

I went back a day later to drive her to the gas station to fill up as she was low. When she started, the ammeter wasn't working again. The battery wasn't drained or anything, but I wasn't getting any charging.

I got out the test procedure you sent me the link to and started testing. Test 1, 2 and 3 passed. When I got to 4, joining wires D and F from generator, I fail and get pretty much zero volts which says my problem is earthed F lead. If this means my wire from the F terminal on the generator is grounding out somehwhere, then I am lost as I installed a new wire from generator to regulator and it isn't grounded anywhere.

Any thoughts? I hate dealing with electrical issues...

 

[TR3driver]

Just to make sure we are on the same page; you did the test where you link the two terminals on the generator, and it ran up to 20 volts when you revved the engine up just a bit.

Then you reconnected the two wires to the generator, and disconnected them from the control box. Checking from D to ground, you found 2-4 volts with the engine at fast idle.

Now you are doing the test where you leave the two wires connected to the generator (but not connected to the control box), and connect the two wires together at the control box end. This is exactly the same as test 2, except the two lengths of wire are now in-circuit. And you say you are seeing zero volts with the engine running at fast idle. Since you saw 20 volts in step 2 (which shows the generator works), and 2-4 volts in step 3 (which shows the D wire is good), but now zero, then either the generator is intermittant or something is shorting it to ground.

At this point, I would repeat step 4. If you still find nearly 0 volts, disconnect the F wire from D while still measuring voltage on D. If the voltage goes up to 2-4, something must be shorting F to ground. That something could be inside the generator (but then it would have flunked test 2).

My guess would be that the F terminal on the generator is not properly insulated, and is shorting to the case when you install the wire. Or possibly the terminal on the wire is touching the case some how.

If you have the original style generator, then the F terminal is only insulated from the generator end plate by some phenolic tubing. That tubing may be cracked or broken, and the terminal moved enough when you attached the wire to ground it. Or possibly the tubing is not long enough, and the terminal came up against the case.

Later models have different arrangements, though. ISTR the later generator with the Lucar connectors has a square nylon sleeve where the field terminal goes through the end plate. But the same thing applies, I'd be looking closely at that insulator.

Another test you could make is to measure the resistance from the F terminal on the generator to the case. It should be around 5-6 ohms. If it's much lower, then it's still shorted. Make the same measurement with the wire connected.

 

[TR3driver]

Another possibility : the yellow wire from the 'D' terminal has a bad connection either at the generator or broken somewhere inside. It could be passing enough current to power your voltmeter (which is a very small current indeed) but not enough to register when the load of the field is added. Measuring the resistance through the yellow wire to the case should produce under 1 ohm.

 

[6969ronin6969]

Randall,

Thank you for your patience in helping me out. The last 3-4 weeks have been prime driving weather and i have been without my TR the whole time, very frustrating.

Anyway, I am glad you took the time to verify we are on the same page. With regards to test 1, I did not get anything like 20 volts when I revved the engine. I got a steady rise of voltage as I revved the engine, but it got up into the 4~5V range if I recall correctly. Sounds like that is not what the manual was expecting (either I missed it or I wish it could have been a little clearer for the electrically challanged, like myself).

Sounds like the rebuilding process is not working for my generator, would you agree?

Thanks,

Eric

 

[6969ronin6969]

Anyone have a spare generator they'd be willing to sell inexpensively? I don't want to dump alot on this (have dumped too much already) because i want to switch over to an alternator eventually, but I am not ready just yet. I want to do that when i replace my wiring harness and someother electrical odds and ends so that I have a nice clean harness when finished.

Thanks,

Eric

 

[TR3driver]

Anyway, I am glad you took the time to verify we are on the same page. With regards to test 1, I did not get anything like 20 volts when I revved the engine. I got a steady rise of voltage as I revved the engine, but it got up into the 4~5V range if I recall correctly. Sounds like that is not what the manual was expecting (either I missed it or I wish it could have been a little clearer for the electrically challanged, like myself).

Yeah, it's a lot less clear than it could be. But that is what they meant when saying "full scale reading at fast tick-over". I'll add a note.

(BTW, this is test 2 in the manual, not test 1. Test 1 should only produce 2-4 volts.)
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
Sounds like the rebuilding process is not working for my generator, would you agree?
[/QUOTE]
Well, considering that I just took mine back apart for the 4th time, I will agree that it sometimes doesn't work. I might have a few pointed words with the people who rebuilt it last time : even if they only changed brushes & bearings (which is usually all that is required), they should have tested it electrically.

But if you only got 6 volts in step 2, then there is clearly a problem with the generator.

Sorry I don't have one to offer. Lots of them in the parts bin, but they are rebuildable cores at best.

 

[TR3driver]

They rebuilt the generator again, not 100% sure, but something about the solder being melted.

Hmm, I just picked up on this. If the solder was melted where the wires connect to the commutator, then that is a sign that the armature was severely overheated (which is a common problem if the control box fails to limit the output current). At that point, even if the armature appears to work OK, it should be rewound or replaced. The heat will have also deteriorated the insulation between the windings, which will eventually (if not already) lead to an inter-winding short.

With an inter-winding short, the generator may appear to work normally at first, but will be working extra hard to overcome the current through the short, so it will quickly overheat again. Unfortunately, there is no simple test for an inter-winding short (unless you happen to have access to a growler).

 

[6969ronin6969]

Thanks again for explaining things to me. It does make a little more sense, but still just as frustrating.

I went ahead and found another gnerator (my apologies if I just outbid someone on here) so hopefully I'll be up and running by this weekend or early next week.

I'll check the generator first after installing on the engine, but before I hook it up to the circuit, and post final (hopefully) results.

Take care,

Eric