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Hey C/O;
Amateur hour, I realize, but it's been a while since I've worked on my own car (which was a 79 Cutlass, back before time began). In any case... I'm swapping the alternator in my new-to-me-'68 Cutlass S/350 this weekend ). Likely I could have gone with the $45, 55 amp Delco, but the car has a stereo amp (buried under passenger front seat, so I don't yet know the wattage), I decided on the 100 amp Powermaster: https://www.summitracing.com/parts/PWM-7102
My primary question is in regards to the tensioner. Is there such a thing as too much tension? I'm presuming I'll use a pry bar to set the tension, but again, not sure how much that should be. I'm thinking "tight to the point of not over-forcing it" will be correct.
Second one: I've read a lot about clock position, but, that wasn't an option for configuration. The fitment does match the 350/5.7L so I'm thinking it will be correct, but if it is not, I'm guessing I need to change it or send it back. Any thoughts on that?
You can have a belt too tight, it will kill the alternator bearings and wear the belt excessively. If you have 1/2-3/4 inch of belt deflection, your probably ok. They make fancy tension gauges, but it’s usually more trouble than it’s worth.
If the plugs and wire connections are accessible, then the clock position you have will work.
Last edited by matt69olds; Oct 30, 2021 at 10:01 AM.
If you have 1/2-3/4 inch of belt deflection, your probably ok.
Thank you matt69olds! To be sure, if I understand correctly, you're saying, I should be able to push (or pull) the belt up or down a half inch or so. Appreciate the help!
So alternator replacement went great. Sorta… I had to adjust the bolt position of the new alternator to align correctly, but that was no problem. Car fired right up and idled normal, 10 or 15 minutes. Tension was a little too tight (less than a half inch deflection),so loosened it just slightly. Fired right up again; all systems go, radio, fan, lights etc. (Picture below).
Here’s where the fun starts.
Took her out for a cruise and about a mile out, radio died followed directly thereafter by the car itself. Puff of smoke under the hood confirmed a complete meltdown of a thin wire off the hot battery lead, which seems to go to a resistor (?) mounted to the firewall.
coating completely melted off, wire burned in half. I am getting a spark (and heat) connecting the two halves, but no power/lights of any kind whatsoever - like the battery is shot, but obviously not. Completely in the dark (no pun intended) as to what this could be. Any thoughts?
Potentially the external regulator?
Sounds like the fusible link did it's job: melted - to prevent more severe damage elsewhere. Now you need to figure out why it did it's job.
I'm not much help here, I'm just learning the finer points of the charging system myself. I've installed a new pigtail at the generator, and a new external regulator (on firewall) on my '68 4-4-2, but can't get the generator to put out any current even though the regulator tells it to Charge!, LOL!
For Clarity:
Power Distribution, Horn Relay and Fusible Link:
External Regulator:
Last edited by BackInTheGame; Nov 1, 2021 at 07:31 AM.
Some questions:
-What indicated to you that the alternator was shot? Hopefully, you didn't turn in the old alternator for the core?
-Do you own a VOM (volt-ohm meter)?
-Where is that large green wire going? Is that the positive cable off the battery? If so it's routed wrong.
The battery is installed wrong. More accurately it's the wrong post orientation on the battery(wrong part and group #), The negative should be towards the radiator core. The positive connection should be closer to the washer bottle. But the battery should still do what you want it to do.
The Neg wire should be connected to the block under the alternator, not on an intake bolt.
Take a picture of the rear of the alternator. the horn relay and the remote voltage regulator mounted on the firewall to the left of the windshield washer motor.
Thanks droldsmorland, I'm not sure how to use the multi-quote, so answers are underlined after all your questions.
Originally Posted by droldsmorland
Some questions:
-What indicated to you that the alternator was shot? Hopefully, you didn't turn in the old alternator for the core? — Alt worked okay, but was very noisy/rattling and all external bolts were tight. But also, my dash lights seemed very dim compared to my '72. I still have the old alternator.
-Do you own a VOM (volt-ohm meter)? No
-Where is that large green wire going? Is that the positive cable off the battery? If so it's routed wrong. — NO, not connect to any cable. I think it is wrong, but just goes from the quarter panel to the engine block.
The battery is installed wrong. More accurately it's the wrong post orientation on the battery(wrong part and group #), The negative should be towards the radiator core. The positive connection should be closer to the washer bottle. But the battery should still do what you want it to do. — Totally aware, tried to turn it 90• but, then the brackets didn't work
The Neg wire should be connected to the block under the alternator, not on an intake bolt. — Good to know
Take a picture of the rear of the alternator. the horn relay and the remote voltage regulator mounted on the firewall to the left of the windshield washer motor.
Have to do this later, when I'm with the car, but, at first glance does appear same as Back in the game, except the red wire leading to the relay is now melted!
BUT... on that note, that's the second time that red wire has melted. The first is when I jump started the car, about a month ago, shortly after I purchased it. The interesting part of this is an aftermarket Radio Shack noise reducer was installed at some point, with a 7.5 amp fuse. I'll take a picture, but, it is mounted to the fender wall, in front of the horn relay. I believe this was installed with the 50 watt stereo amp that is tucked under the driver seat. The first time I jumped the car, I removed the 7.5 amp fuse, and all was good. The second time, I forgot to take the fuse out and the jump melted the same red wire. Co-incidence?
it does seem clear that the 100 amp alternator is creating too much voltage, similar to what the jump must have done. But the question is, why? I believe something is grounded that shouldn't be, or visa versa, in my extremely limited knowledge of this.
Thanks Yellowstatue. Gonna give that another stab. I think there was some issue the first time I tried. And, as a further update, Summit is taking this alternator back. Had my mechanic check the wiring and he almost instantly suspected the alt. Upon testing, he found it has an internal short with a ground wire.
Summit asked no questions on this, but I think they realize that a simple alternator swap would not create this issue anyway.
Do not take this personally. There isn't enough space here to begin to steer you down the path to a proper permanent repair.
I'm gonna take the road of suggesting you farm this electrical problem out to a good shop that knows old electrical systems. I don't want to see you get frustrated with your new ride and spoil the fun. Or burn it you and a garage to the ground due to a short. A stereo installed under a seat is a recipe for disaster.
You will actually save time and money this way. Purchase the correct parts and start from scratch. Safer and cheaper in the long run
Install a high-quality battery disconnect from somewhere that doesn't sell general-purpose cheap inferior big-box chinese junk. Again for safety. A good one will be north of $25. Try to find all parts made in the USA(lol). Disconnect it whenever not in use, It acts as a theft deterrent too as the green **** is removable and you can stick it in your pocket.
I'll assume you didn't turn in the OEM alternator to Summit. Look at getting it rebuilt by a local starter/alternator shop. You don't need a 100 amp alternator. 55 should be sufficient unless you have a high amp stereo? I'm pretty sure the old alternator can be upgraded for higher output.
Clean all grounds and positive connections from the battery down to the starter This includes the starting and charging circuits. Even the voltage regulator needs a good ground on the firewall. Move that neg cable off the intake and mount it to a clean spot on the block behind the steering pump where it belongs. The correct size bolt and washers are reproduced. Its a shallow bolt. It might still be there? Engine (rear of the heads) to firewall braided ground straps are reproduced and are cheap.
Disconnect all the aftermarket stereo and other stuff and start over. The correct wire harnesses and sub harnesses are being reproduced to replace the fried wires.
Get a new set of correct battery cables from Fusick or Year One,
Get an assembly a chassis, and an electrical manual. All are available. The assembly manual will show the correct battery cable and other harness routing(s). Even if you cant interpret the electrical diagrams your mechanic will thank you for providing them.
The same "group" of batteries come in several different post configurations Top post with the positive on the left or the right or side mount or even a combination of top and side. The right group will fit the battery tray with the correct post configuration.
The grounds are critical for proper DC system operation, especially for a 54-year-old car. Clean every connection you can get to.
Practice with the multi-quote box in the lower right. Look at other posts that are multi quoted and you will get it. Sorry, long-winded tonight....in an airport on a layover,
even though the regulator tells it to Charge!, LOL!
