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drooartz

drooartz

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I've been having trouble with my alternator (conversion by PO) on my 62 TR4. It doesn't seem to be charging. I checked through the wiring and made sure it matches the factory diagram and the instructions I found on the conversion. Also checked all the connections and grounds. That all seems right. I had the alternator tested at 2 different places, and it tested okay at both.

With the alternator hooked up, I get a pulse of + on the amp gauge about once a second. Voltmeter across the alternator shows the same thing, a pulse of higher voltage about once a second. Otherwise, it doesn't seem to be charging the battery. I would expect it to be showing a slight + charge with reasonable RPM and no lights on.

I've been getting some help from the Triumphs email list, but so far haven't found the problem. I'm officially flummoxed. Any thoughts?
 
Hello Drooartz,

what alternator is it and is it one with an internal or external regulator? Also what are the voltage readings you are getting?

Alec
 
Most of the alternator conversions use a Delco 10SI unit that has an internal voltage regulator. The generic number used by most rebuilders is 7127. It has the main battery hook-up coming out the back, and just above that to the right will be a where a two wire connector plugs into the back from the side. Is that what you have??

Edit: Here is a picture of the Delco 10 SI
 
[ QUOTE ]
Most of the alternator conversions use a Delco 10SI unit that has an internal voltage regulator. The generic number used by most rebuilders is 7127

[/ QUOTE ]

That picture is indeed what I have. This was done by the PO, so I'm learning a bunch about the install as I go. I'll have traced out my entire wiring harness by the time I'm done fixing this. Not a bad project, at that.

I do have a related question on the physical install. It seems that the PO ground down the lug on the alternator that is used to attach it to the generator mount at the block (to space the pulley properly, I assume), and is using the (modified?) top bracket for mounting. This puts the alternator out near the inner fender, with essentially no adjustability for belt tension. Seems a little screwy to me. Does this sound normal? This conversion uses the pulley off of the generator (again, AFAIK).

-Drew
 
Drew....
You can adjust how close the alternator sits to the inner fender by using a shorter fanbelt, just take your old one to a parts place and they will figure out one for you.
You really need to give us some voltage readings with the engine running above idle. Take them at the alternator and also at the battery.
With the engine off, and ignition in the on position, check there is battery voltage at the smaller wire going to the alternator, I think it's a brown/yellow wire.
 
Voltage reading at the battery (ignition off) is about 12.75. With the car idling, it is the same, and about the same as measured at the alternator.

Above idle, the voltage starts out the same, then about once per second it jumps to maybe 13.25 or so. At the same time, the ignition light will go out, and the amp gauge will jump to positive. Watching my voltmeter, I get these little jumps at a regular frequency, about once per second.

Voltage to the #1 post on the alternator (from the warning light) pulses at the same rate, although I did try running a test lamp from #1 to a 12v source and got the same jumping of voltage at the alternator. The test light stayed solidly on.

Someone on the Triumphs email list mentioned that the voltage stabilizer cycles at about once per second. Not sure if that is related at all. The PO did put in a new harness, so there is no guarantee that the wiring is correct.

With the alternator hooked up through the stock wiring, what should the amp gauge be reading? This would be at, say, 2500 RPM with no lights on.

This regular cycling thing is very odd. Any ideas?

-Drew
 
Coming out of the two wire connector is one wire that is probably hooked up directly to the threaded post on the back of the alternator. This is the usual place that people put this wire. It is the battery sense wire, and although it will generally work in this position, it is not the correct place for it. If it wass the correct place for it, Delco would have wired that internally inside the alternator. It should go directly to the battery. When it's at the back of the alternator, it's measuring the voltage output of the alternator, not what's getting back to the battery. Try unhooking this wire from the stud, and add a piece of wire so it goes directly to the battery (+) positive. See if this fixes the pulsing.
 
In my old days with GM dealerships, these alternators would max out at about 14.5 - 14.75 volts. Higher than 15.25 was no good and below 13 was usually brushes or the internal voltage regulator going south. Both are easy to replace, but first, have you checked the belt tension to make sure it's tight? Not meant to be an insulting question, but often overlooked, especially if the belt is older and stretched a bit.

Paul
 
[ QUOTE ]
Coming out of the two wire connector is one wire that is probably hooked up directly to the threaded post on the back of the alternator.

[/ QUOTE ]

I did get this advice as I was starting my troubleshooting, and that wire is now hooked to the battery side of the starter solenoid.

[ QUOTE ]
below 13 was usually brushes or the internal voltage regulator going south.

[/ QUOTE ]

I've had the alternator tested at 2 different shops (Pep Boys and Checker) and both times it tested okay on their gear. I suppose it could till be bad even with the passed tests, though. The belt is a bit loose, but I didn't think that would be causing the pulsing problem--it seemed to regular for that.

A question on the wire coming from the ignition warning lamp: Should this have a steady 12v, or will it go off when the light goes out? Right now the voltage drops (test light hooked up to this blinks in time with the alternator pulsing) when the light goes out.

-Drew
 
Sometimes those testers are simply a "go / no-go" test that can fall in at the high or low end of the spec. I would have it checked with a volt/amp meter under a load and at idle and higher RPM without a load to be sure.

Again, the alternators are relatively simple to disassemble and the new brush holders come with a plastic rod in place to hold the brushes in place until you assemble the case over the rotor (which may need cleaned when you look at the contact area for the brushes - use commutator paper for this and make sure no grit is left behind) and then pull out the rod to allow the brushes to contact.

Scribe a line on both halves of the case to make sure that you put the two halves back in alignment the same as they came apart, so that your mounting brackets fit the back properly.

Paul
 
[ QUOTE ]
Sometimes those testers are simply a "go / no-go" test that can fall in at the high or low end of the spec. I would have it checked with a volt/amp meter under a load and at idle and higher RPM without a load to be sure.

[/ QUOTE ]

I'm trying to avoid replacing the alternator until I'm more sure that it is the failing component, mostly because I want to really understand how to hunt down the problem. I am learning a bunch about how the electrical system works, and that's been very educational. I have heard that the tests at the shops may not be 100%

A question on the wiring. The wire that comes through the dash light to #1 on the alternator--should this be reading the same voltage as the rest of the car? Should it be constant 12v (or 13 ish) or should it drop out when the light goes out.

-Drew
 
Actually, it's the other way around. When you first turn on the ignition, and before you start the engine, the dash light will come on. At that point, you should see very little voltage (maybe 0.5 VDC) at the #1 light terminal of the alternator connector. When the engine is startred, and the alternator energizes, the dash light will go out, and the voltage reading will go up to 13.5-14.5 VDC at that terminal.

One more question, does the frequency of this pulsing change with engine speed??
 
As Martx-5 said, the voltage on the indicator lamp should change when the alternator is working. The lamp (bulb) must be OK for the system to charge (unless the alternator is a so called one-wire type). Current from the ignition switch passes through the indicator lamp and goes to the alternator field coils (stator). This power energizes the coils until the alternator is "up to speed" at which point it "self energizes" if it's working correctly. At this point, the lamp connection on the alternator goes up to charging potential. Since both sides of the lamp (should be) close to 14v, the lamp goes out.

The pulses you're seeing are very curious. The voltage stabilizer does "pulse" but it's usually at a much higher frequency than you would notice and isn't connected to the ammeter anyway.

There is a diode-trio and a regulator inside the alternator. I believe the diode trio is what interfaces with the indicator lamp during self energizing. It could be that this is failing. There is a very knowledgeable guy on the MG/Spridget part of this board (Sparkydave) who could probably give you some good pointers on what to check. You may want to send him some mail.
 
[ QUOTE ]
One more question, does the frequency of this pulsing change with engine speed?

[/ QUOTE ]

Only in the sense that it doesn't start its pulsing until the engine gets to a faster speed (say 2500 RPM). It is fairly constant after that, not faster or slower as the engine speeds up beyond that.
 
[ QUOTE ]
[ QUOTE ]
One more question, does the frequency of this pulsing change with engine speed?

[/ QUOTE ]

Only in the sense that it doesn't start its pulsing until the engine gets to a faster speed (say 2500 RPM). It is fairly constant after that, not faster or slower as the engine speeds up beyond that.

[/ QUOTE ]

Although there is pulsing in the alternator at those speeds, it may well check OK on a test bench at the auto parts store. They generally only test at about 5-6k alternator rpm, where it's loaded down. Under those conditions (alternator fully loaded) I would bet that the pulsing disappears. When we test alternators at work (I work for a large electrical re-manufacturer), the test procedure is very complex. We test under a variety of speeds and conditions. Performance curves are generated, and any anomolies are readily detected. This is not available in most testers available at parts stores.

I have seen many voltage regulators for the 10SI Delco perform what we call "crude". They have a very coarse regulation especially under lighly loaded conditions. My best guess at this point is that you have one of these coarse aftermarket regulators and it is giving you the symptoms you describe.

To test this theory, while you have the alternator running at a speed where the pulsing is, start turning on as many lights and accesories as possible and see if the output smooths out. Also, have the voltmeter attached to make sure the voltage doesn't drop below about 13.5- 13.7.
 
Thanks for the new directions, especially martx-5 and Doug. I'm still frustrated, but I'm learning a lot. I had no idea how the ignition warning lamp worked. If the voltage from the alternator were slightly low, would the the lamp just glow dimly? On my one test drive recently, it did do that once I had run the car for a little while. Amp gauge read flat to -.

I did a couple of tests, and here's what I came up with:

No load:

12.5v with car turned off
12.5v at idle
13.5v pulse

Load (lights, fan, turn signal)

just under 12v at idle
12.5v ish at pulse

Voltmeter was connected from BATT to ground. It still pulses even under load. Checked the ignition lamp voltage at #1 as well. With key and light on, voltage is about .5 - 1ish. It then jumps up to 10+ with the pulses. The pulses seem rather quick, so the gauge may not be able to register fast enough, so I would guess it's getting at least close to the full voltage during the pulse.

So am I looking at replacing the alternator? It looks like the PO did some grinding on the lower mounting point on the alternator (where it attaches to the block at the generator mount). Is this common? The install uses the generator pulley, and some sort of modified top bracket (I think, I've never seen an original one). It seems that I've ruled out most other things, which I wanted to do before I started replacing the more expensive parts.

-Drew
 
As soon as the voltage output from the alternator starts to dip below battery voltage, the dash lamp will start to glow. According to the latest info you have given, your alternator is not putting out enough. The first thing to do is to make sure the the drive belt is tight enough. You mentioned earlier that the adjustment was at the end of the rope. Either the alternator belt is slipping, or the alternator itself is has some problems. Your voltage readings when loaded up are too low. /ubbthreads/images/graemlins/hammer.gif
 
Check the price for new diode trio, brushes and holder and voltage regulator. It may be cheaper to buy another unit. I read in the 6-Pack magazine article that the writer bought his for about $40.00 at one of the auto chain stores.

You should be at the specs I posted earlier, 13.5 to 14.75 even with the lights on.
 
I'm considering now just going back to the generator/voltage regulator setup. The PO did the alternator conversion, and included the old generator. I'm not intending to run any accessories, and that might just be simpler. I like simple! Just need to get a new voltage regulator, and a few miscellaneous brackets and bolts, and I'll be back in business. Might just be my next order...

-Drew

Thanks again all for all your patient answers to my ongoing electrical saga. It has been very educational for me. Sure is nice working on a car with so few wires!
 
Consider the possibility that you may get the same symtoms after you go back to the generator-not a happy thought is it? The Delco alternator is very easy to rebuild and the parts are not expensive. If you can get it to work, it will cause you much less aggravation in the long run than a generator. There are only a couple of bits in the unit that could cause a charging problem, although the other guys were right about a loose belt too. If you rebuild the alternator and it works, you are happy, if it doesn't fix, well, you still would have to continue the trouble shooting after you put the generator on. Is it possible to install another alternator without the ground off lug even if the alignment is not perfect? If you have a buddy with an old chevy truck, you could swap in a known good alternator. Tell you right away if the problem is the unit or the car system.
Don
 
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