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Electrical / Car Dying Issue
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Hello,
'65 GTO, with 455, '65 Tri-Power, MSD Dizzy, 6AL box, blaster 2 coil. I had an electrical short that resulted in the car dying as I backed out of the driveway. There was smoke emanating from under the hood after a few failed restarts and I found a frayed wire had shorted, the current jumped to another wire and they melted together. See the first photo. All fixed and I have driven the car twice. Today, it died on me twice, but I was eventually able to limp home. I pulled the main coil to dizzy wire and noticed some minor melt. See the second photo. I've pulled the coil and measured ohms. Primary 0.7 - 0.8 ohms. Secondary 5,800 ohms. Any opinions? I have very little experience with electrical. The wiring is 25 years old. I'm thinking of replacing the entire wiring harness and making everything nice. |
I believe those two wires in the first photo are supposed to be two separate wires from two different sources. The yellow/blk I believe should be full 12 volts, the other is a resistor wire and should begin black with red or pink stripe. Not sure about the colors, but they shouldn't be spliced together. The full 12 volts is for cranking, and the resistor wire is for run, both power for the coil for different purposes. That being said, you should only need one now, for the msd, and it should be full time, full 12 volts. Hopefully someone else will interpret your coil resistance values.
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Thank you Scott,
When I dug into the engine harness last time, there was all sorts of confusing things. You should see how my alternator is wired! I think I need to bite the bullet and re-wire from the fuse block forward. I'll post some more photos in a couple of hours. |
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I don't know what kind of shape the rest of the harness is in, but those two wires can be replaced at the bulkhead connector. I did it years ago to get rid of the resistor section. Nowadays, I have those two wires run to a junction block, and have a source for 12 volts hot in crank and run position of the key. I use it to power relays now so it doesn't see much load. The alternator wiring is pretty easy to re do also. The master splice was in amazingly good condition on my car, but i completely replaced it all with stuff from MAD electric anyway. Not trying to discourage a new harness, but it may or may not be necessary to correct your issues.
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Do you by chance know where I can buy a 10 hole bulkhead connector? I think they are called series 56 Packard.
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No, I only replaced the wire/connector. The bulkhead itself still functioned fine on mine.
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The Packard bulkhead connectors and fuse blocks are not available individually, they only sell a min of like 500 or 1000. I tried. You can salvage some from a boneyard though, or someone who has replaced their engine/forward light harness.
The Packard connectors are 56 type, readily available at any auto wire warehouse online. Many also sell the open terminal crimp tool, the Casper one is fine (@$30). https://www.waytekwire.com/item/419/...Crimping-Tool/ Wow, when was the last time the plug wires have been replaced? The coil one specifically? Anyway, yeah, if the engine harness is dated, and has previous damage/mods, you may want to seriously consider a replacement harness. You can have valuable options added, like an 'HEI' upgrade which removes the resistor wire, internally regulated alt, and similar options. That will give you a line in the sand, and remove many of the areas that are in question. Also would simplify any troubleshooting and repair. (It's much easier to replace the engine harness than it is to troubleshoot and repair). You say 'it died today, but was able to limp home'. How did it die, it just cut off like a light switch, or it was sputter and chug and fizzled out? What did you do to limp it home? . |
HWYSTR455,
I will answer your questions/comments, then give you an update: I purchased some female Packard 56 ones from both Pep Boys and Amazon, and they are about 2m shorter than the ones in my bulkhead connectors. We reused the one connector on the melted resistor wire we had to remove to be sure it had the depth into the fuse block. It's amazing those bulkhead connectors aren't available. I will bookmark that crimping tool, thank you. To my knowledge, the spark plug wires are early 90's and have about 16,000 miles on them. I have no idea if they need to be replaced. I replaced the coil about two years ago, but never the coil plug wire. The car would intermittently stop revving over 4,000 rpms. Replacing the coil fixed that issue. Please let me have your opinion on the wires. I can send photos if you like. The spark plugs are new R43S, gapped at 0.045, Yes, the engine harness is dated, and yes I ordered a new one from M&H. Unfortunately, they didn't have the HEI modified one, only standard. But, they are including a wire to replace the resistor wire. The salesman said this is the only difference. I will simply ignore the wires for the old 3-wire ext. regulator alternator. Additionally, I ordered a front headlight harness from Ames, which is from M&H, but M&H didn't have stock, so I went to Ames. The headlight harness should include horns and parking lamp wiring too. Because I like spending the maximum amount of money, I also called up Mad Electric and bought a kit from them for headlight relays, electric fan relays, alternator wiring, diodes, and God knows what else. After Labor Day, laboring on diagnostics for hours, I am 100% on board with your assessment that it is much faster to replace everything. Yes, on Saturday the GTO died leaving a friend's house. Just cut off. I started it and it idled for about 10 seconds then died. It wouldn't start for a couple of minutes then somehow started and I drove around the block and it cut off again. A couple of minutes later I was able to restart and make it the four blocks to my house. The cut off was the same type of cut off as the previous short on the resistor wire. I'm about to download installation docs for my AutoMeter Sport Comp 3.5" tach, my MSD 8563 Dizzy , and my 6AL 6420 ignition box. I have an automotive wiring book on the way and good instructions from M&H too. Let me know what you think about the spark plug wires. |
Sounds kinda like vapor lock symptoms...
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It wasn't that hot out, maybe 75, and I have the special spacers between the carbs and intake. I thought it maybe was something like that, but I've never had any issues before. To be honest, I really don't know what it's like to have vapor lock.
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Also, you can check the general condition of your plug wires with a multimeter. Check resistance. Its helpful if you check them when they're new, but you'll get a general idea even if you didn't.
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What would be the correct ohms/foot for MSD spark plug wires?
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I would say 50 ohms/ft would've been considered good when they were new. I haven't noticed degradation on Pontiac wires being bad. My wires I took off in the spring after 18 years still were about 50. I attribute that to them staying above and out of the way of the exhaust, as opposed to some others where the wire runs down by the header. Post your results, I'm sure you'll get input.
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Plug wires last like 5 years at best, if they are older than that, regardless of miles, it's time to replace them. Service intervals for vehicles back in the day were 2 years or 24k miles I believe, and that was with points, low voltage ignitions and old-tech wires. It's close to the same interval these days with HEI or high-output ignitions and quality wires.
MSD boxes eat wires. I argue that measuring ohms is a good test for wires, other than finding ones with breaks in the core. The jackets are silicone, break down over time, and leak. That scenario may still show good ohms on a wire, but they are 'bad', and in need of replacement. It doesn't look like you changed the coil wire when you did the wires last time, that's where my comments came from. That coil wire looks like crap. I would suggest a good cap and rotor too, not parts store stuff, especially with an MSD box. Caps & rotors too, it's general maintenance. You wouldn't not change the oil at 5k miles if you thought the oil 'looked good' would you? Pepboys and amazon are questionable sources for those 56 series connectors, use a valid auto wire supplier and buy name brand. https://www.waytekwire.com/item/3103...ose-Terminal-/ https://www.waytekwire.com/item/3103...ose-Terminal-/ They make terminals for 10-12 gauge wire too if you choose. These terminals are not just used in the terminal block, but other OE Packard connectors too, so don't feel like it's a waste to buy a min of 50, it's only like $8 anyway, probably more than you spent for the cheap ones. Get heat shrink tubing too, I prefer the adhesive type, and there too, don't buy cheap auto parts store crap. If you're placing an order for stuff at Waytek, I suggest getting some high heat seamless butt connectors. Get a Klein 1006 crimp tool, with the Casper tool and the Klein tool, it will cover like 90% of electrical needs. Home Depot carries the Klein tool, or Amazon it. (@$30) You will be happy you did. A good vid from Holley about crimp & solder is worth a watch, even as a refresher for experienced people. I point others to it: https://youtu.be/faLn-SjVfwY That coil wire to the dizzy could be cooking or overheating coils, but once you get the new harness (EDIT: and new wires) installed, see how things work out for you. Report back. . |
I like using a plug wire crimp tool and MSD Super Conductor 8.5 universal wires, with the multi-angle boots. They are great, quality wires, my go to.
https://www.summitracing.com/parts/sum-900399/overview/ https://www.summitracing.com/parts/msd-31153/overview/ A can of spray silicone make slipping the boots on the wires easy. . |
Cut the crimp link off and solder it then tape it. Make sure you cut the tape with scissors, never stretch and brake tape..
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HWYSTR455,
I ordered what you suggested from Waytek, except the high-heat butt connectors and heat shrink tubing. I need to roll to work and didn't have time to shop. Can you post a link of a Waytek kit for those and I'll order at the office? What Klein crimper do you like? Can you post a link? I may already have it. Understood on the plug wires, cap, and rotor. Do you have a recommendation for those? I have MSD Dizzy #8563. Off to work. |
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Solder in the engine compartment is not always a good idea, it can reach temps that are enough to melt solder. . |
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https://www.amazon.com/Non-Insulated...a-382712975494 Here's the nickel plated high heat butt connectors, 2 gauge ranges: https://www.waytekwire.com/item/3246...tor-12-10-AWG/ https://www.waytekwire.com/item/3146...tor-16-14-AWG/ Another comment, ONLY use GXL or TXL wire on a car, no parts store 'primary wire'. It can't stand the heat and has higher resistance. I like using WireBarn.com, they are very good prices, quality items, and fast shipping. https://www.wirebarn.com/GXL-TXL-Wire-_c_530.html GXL is fine, maybe look at the 'assortment' kits. 12 gauge for high loads, 14 or 16 for everything else. WireBarn has heat shrink too, most common sizes are 5/16, 3/8, and 1/2 inch: https://www.wirebarn.com/Heat-Shrink-Tubing_c_11.html The MSD replacement parts specified for that MSD distributor is the way to go. They make both red and black colors, either is fine. This is the black cap & rotor kit at Summit: https://www.summitracing.com/parts/msd-84317 Red kit: https://www.summitracing.com/parts/MSD-84335/ . |
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