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FYI the alternator grounds out through its body to the block. If you have the case powder coated or painted where it touches the block has to be bare metal or you will have problems.
Taking apart the alternator and putting back together is trickier than you would think. I would make sure you have a good alternator first then if you want to paint/powdercoat do that down the road. It's a 10 minute job to pull the alternator and that's taking your time, no big deal to do it down the road.
FYI the alternator grounds out through its body to the block. If you have the case powder coated or painted where it touches the block has to be bare metal or you will have problems.
Taking apart the alternator and putting back together is trickier than you would think. I would make sure you have a good alternator first then if you want to paint/powdercoat do that down the road. It's a 10 minute job to pull the alternator and that's taking your time, no big deal to do it down the road.
Dale
Lol it's pretty easy, but I dunno about 10 min unless you've done it a few times or have an aftermarket intake and no air pump (or just happen to be Dale Clark). Reaching in there to drop the air compressor was a pain in the butt (you need to find your favorite wrench and spy the tensioner bolt, that'd be way nicer without the stock intake). I think I could get one out in <20-30min now, and I'm pretty slow and distractible. I'll try to go deliberately and time it and report back. That ought to give a high-side estimate. Just need work to calm down.
FYI the alternator grounds out through its body to the block. If you have the case powder coated or painted where it touches the block has to be bare metal or you will have problems.
That's a great point Dale. I did know that, and IIRC, when I got the FD and had everything apart when I was doing my wiring harness build, I'm pretty sure I checked that the alternator case mounting points had the powder coat grounded off down to bare metal. But it was so long ago now I'm not 100% sure and would have to check. Though I only see a voltage drop after the engine bay is thoroughly heat soaked; if the alternator case had a poor ground connection, I'd expect that I'd see the voltage drop on cold starts and every other time too, no?
Originally Posted by DaleClark
Taking apart the alternator and putting back together is trickier than you would think. I would make sure you have a good alternator first then if you want to paint/powdercoat do that down the road. It's a 10 minute job to pull the alternator and that's taking your time, no big deal to do it down the road.
Dale
^True. Alternator disassembly/assembly can be a PITA - done at least a half dozen FC alternators and the FD ones are about the same as far as mechanical design & construction goes.
Though I only see a voltage drop after the engine bay is thoroughly heat soaked; if the alternator case had a poor ground connection, I'd expect that I'd see the voltage drop on cold starts and every other time too, no?
Alternator disassembly/assembly can be a PITA - done at least a half dozen FC alternators and the FD ones are about the same as far as mechanical design & construction goes.
Mine did the same thing, the voltage regulator‘s taking a vaca.
Pete, you should have no problem switching the case on an FD alternator if you did the fc. It’s really not as bad as everyone leads on. After you get it split apart, despite what the FMS says, leave the voltage regulator soldered in. Just bend the strands out of the way slightly to get the screw holding it down. From memory the other three screws are out in the open. Just pull the entire assembly out as one and switch it over to the new case. Then you can easily but gingerly bend the strand back into position. It will make sense once you get it apart. The hardest thing is removing the pulley off the front. Just remember to index the case alignment before taking the front cover off. If you have a little impact, they seem to work best.
Got the Rock-Auto AC-Delco alternator installed last night. I scraped/cleaned the connectors, harness grounds, and engine grounds. Used some dielectric grease on the ground points and terminals. And added the JP3 ground strap on the manifold, cause why not?
Took a little drive and things seem improved. Fancy new multimeter says 14.2-14.4v, which is in range for a rebuilt alternator. The battery is not clearly over-volting or over-heating and threatening to boil. Although, I got a fancy AGM battery, since I figured this would work. I boiled a lead acid battery on that last bad-alternator and now I hate lead acid batteries forever.
I'm also Really Mad at Atkins for selling me that bad alternator. I guess I can't completely rule out some sort of installation error, or that's what I'm telling myself. It registered 18v at the parts store, but I never put my meter on it or checked much. I just took it out and started over.
It took me about 45min-1hr to get the old alternator out. Took me 3 hours to do the whole job. But, it was at 11pm, and I was exhausted and taking breaks and wandering around in the middle of it. Probably about 1.5hrs of real working time, if that.
I wouldn't be too upset with Atkins about the alternator, rebuilds are a mixed bag some times. You'll have one that will test good out of the box and a month later it fails.
I wouldn't be too upset with Atkins about the alternator, rebuilds are a mixed bag some times. You'll have one that will test good out of the box and a month later it fails.
Dale
The highest failure rate for almost anything is very early in its life. That's when component quality or installation issues often show up. Then you usually get a grace period until stuff ages out.
Looks like I'm joining the dead alternator club on my FD now. I'm finding that the one it came with is getting weak whenever the engine bay heat soaks - so after driving around for a while, then getting stuck sitting in traffic I'll notice my voltage dropping below 13.5VDC, and if I'm running a bunch of high-amp loads (A/C at max, fans running max, lights on), it will dip as low as 12.8V at a low idle. Bumping up the idle a bit helps with that, but at only 13.3V~13.5V it's barely charging the battery.
What you describe is exactly what your alternator should be doing. The regulator is temperature compensated for a lead acid battery in a hot engine compartment. An agm battery and/or cold (relocated) batteries may need a slightly higher charging voltage. If you have a lead acid battery with caps, you can check the electrolyte’s specific gravity for a precise read on the batteries state of charge. In another thread I talk about how to raise the charging voltage—if needed. Note that once you start to raise the voltage you will dramatically reduce incandescent bulb life. Voltage is not like boost—More is not necessarily better—your battery only wants and needs what it needs and no more.
What you describe is exactly what your alternator should be doing. The regulator is temperature compensated for a lead acid battery in a hot engine compartment. An agm battery and/or cold (relocated) batteries may need a slightly higher charging voltage. If you have a lead acid battery with caps, you can check the electrolyte’s specific gravity for a precise read on the batteries state of charge. In another thread I talk about how to raise the charging voltage—if needed. Note that once you start to raise the voltage you will dramatically reduce incandescent bulb life. Voltage is not like boost—More is not necessarily better—your battery only wants and needs what it needs and no more.
You're correct regarding the general relationship between charging voltage and temperature for lead acid batteries, but even in a heat soaked engine bay at 70*C or so, the charging voltage needs to be approx. 2.25V/cell for a lead acid battery. A standard "12V" lead acid car battery has 6 cells, so that equates to a required charging voltage of 13.5V @ 70*C. In my case, I'll see voltages dip significantly below that point at idle (i.e., ~12.8V) when any additional electrical loads (e.g., headlights, A/C, etc.) are in play, so my alternator is on its way out. Here's an interesting link and an article excerpt that explains where I got the charge voltage vs. temperature from for lead acid batteries. Charge voltage vs. temperature shows for "charge limit" voltage (blue curve, to charge a discharged battery) and a "float charge" limit (black curve, to maintain a fully charged battery): https://batteryuniversity.com/articl...w-temperatures
there is a chart in the FSM with voltage vs temp for the FD
The only thing I could find in the FSM that covers voltage vs. temp was a battery discharge test on page G-10. That test is done with a battery load tester, so the alternator is not in play. But I did find another troubleshooting chart that shows alternator voltage specs for the FD when at idle, independent of temperature - see excerpt below. According to that, anything less than 14.1V at idle measured between the alternator's B+ terminal and case (ground) is below par. This test assumes you have a good battery that measures more than 12.4V with no load on it.
The only thing I could find in the FSM that covers voltage vs. temp was a battery discharge test on page G-10. That test is done with a battery load tester, so the alternator is not in play. But I did find another troubleshooting chart that shows alternator voltage specs for the FD when at idle, independent of temperature - see excerpt below. According to that, anything less than 14.1V at idle measured between the alternator's B+ terminal and case (ground) is below par. This test assumes you have a good battery that measures more than 12.4V with no load on it.
Do I assume correctly that these alternator voltage tests are done with no major electrical loads (headlights on, etc.)?
Do I assume correctly that these alternator voltage tests are done with no major electrical loads (headlights on, etc.)?
That's correct for the voltage test. The prior step also has you verify that the battery voltage is healthy before testing at at least 12.4V with no electrical load applied. The next step not shown in my pasted excerpt is the current test, where you stick an ammeter (100A or greater) on the B+ alternator cable, and check charging current with all electrical loads turned on, and at 2500~3000 RPMs
Is it safe to unplug the gray plug on the alternator while running? Looks like you need to, to run those tests.
Nope, the plug stays connected. To do the tests, you would back-probe the connector using a pin/paper clip or similar type of probe with your meter. Below is a picture showing how, fortunately this connector is not environmentally sealed, so you can easily back probe to the terminal inside without compromising any seals/insulation.
Using a needle & meter probe alligator clip to back-probe alternator terminals
Does anybody know if that AC Delco alternator is still available (3341163) anywhere? The list of available alternators at rockauto seems to skip right over that number
I posted a tangential issue with alternators and AGM batteries. https://www.rx7club.com/3rd-gen-gene...es-fd-1154706/
Essentially, old technology alternators (like ours) could over-charge an AGM battery, and AGM batteries also need a correct float charge that our alternators may not provide in the range needed. Of course, this is battery-dependent.
Meanwhile, with the exception of my engine harness, all my wiring harnesses are original to the car. Has anyone purchased any wiring harnesses from Ray in recent time? I'd be curious of what those go for these days. Maybe I'll ask him at DGRR next month.
FYI the alternator grounds out through its body to the block. If you have the case powder coated or painted where it touches the block has to be bare metal or you will have problems.
Taking apart the alternator and putting back together is trickier than you would think. I would make sure you have a good alternator first then if you want to paint/powdercoat do that down the road. It's a 10 minute job to pull the alternator and that's taking your time, no big deal to do it down the road.
Dale
I just disassembled and had my alternator case powder coated, was getting a steady 14.1-14.2V when running before. Now, it was idling like 12.2. Guess I have to pull the alternator and inspect.
09-18-22, 06:48 PM
