dmruschell

Hey everyone. I have a 1979 that had the engine rebuilt up earlier this year. To keep up with the added horsepower, we installed the Dewitt's aluminum radiator with dual 11 inch SPAL fans wired directly off of the alternator. The stock alternator wasn't quite keeping up, so I switched it oh with a powermaster 140 amp alternator. Now for the latest round of fun....

I installed the alternator last sunday. On Tuesday, The car just went completely dead while sitting at a light. No Gen light, no click, nothing. So I (finally) had it towed to one of (haha....kind of) my mechanics. He repaired the wiring to the fusible link that had been poorly replaced and it fired up and he sent me on my way. 5 minutes later on my way home while moving right after the fans kick on, the car completely dies again. So after a tow, the mechanic replaces the fusible links, and runs a junction block off of the starter and connects the fans to the block to try to keep the fans from blowing the fusible link. All was well until today.

Today, I drive 10 minutes to class, park and the. The key off and the car is dead just like before. No gen light, no power locks, nothing. So I go to class. When I come back from class, the car starts right up like nothing happened. My clock works, so I checked the time difference to see when the power came back, and it c came back within 2 minutes or me shutting the car off.

What do you guys think it could be? I did t honk a fusible link could blow and then come back 2 minutes later. This car is my only daily driver at the moment, so anything you guys can offer to keep me on the road would be greatly appreciated.

1986coupe

I think you need a daily driver so that you have time to look at this.

Perhaps heat is a factor. How old is the coil? The ICM?

dmruschell

I have 2 other cars, one is a 61 vette I can use in an emergency (and is incredibly reliable). my other daily driver besides the 79 is having some month-long work done to it, so it's MIA for a little while.

What is the ICM? and I'm assuming you mean ignition coil? I haven't seen that it was ever replaced. Would that cause the car to completely die?

MelWff

Have you checked the connections at the battery and at the starter and the ground under the battery box?

dmruschell

The positive battery connection is good. I'll check the ground battery connection. The connection terminals were replaced not long ago, but it doesn't hurt to check. Connection at the starter should be ok since the mechanic recently re-routed the wiring for the fans over to the starter (at least I'm pretty sure he did) a week ago. Haven't checked the ground under the battery box yet. I'm guessing it's fairly easy to spot?

I'm living at an apartment now, so I'll do my best to get under the car. I'm moving to a house with a mechanic's pit within a month, we just need a settlement date. Hopefully it won't give me any more problems at least until I can get into that pit and work on it.

dmruschell

The car worked fine all day and then did the same thing this morning. It's being looked at by the first of the mechanics now and going to check all of the obvious connections. Any more/other ideas?

hugie82

The starter might be loose or there's a bad connection between the starter and the block.

dmruschell

Checked all the obvious connections and it cut out after I got home. It came back after 15 minutes this time. It came back while i was in the car and not touching anything electrical. While it was dead, I took a voltmeter to the battery and it was fine. Then I took a reading at the alternator and it was completely dead. I drove it back and left it so he can give it a thorough inspection.

dmruschell

Took it to my expert Vette specialist mechanic. The clip that joins the wires from the starter to the alternator was melted and had been on fire. Possibly because of a wiring splice done by the other mechanic or possibly from another hidden issue. Will post more when I find out.

7T1vette

If a fusible link at the starter fried and then a mechanic rewired it with regular wire, consider yourself VERY lucky that your car didn't catch fire and go up in flames. If the fusible link failed, there is a DEAD-SHORT in the system somewhere. It is likely in the starter solenoid or the starter...but could be elsewhere in the system. That is exactly why the fusible link was designed into that high-current carrying system--so that a major electrical failure would not cause an engine compartment fire.

So, I am hopeful that your 'new' mechanic has more knowledge and more sense than the last one. He needs to find the primary cause of the electrical short and fix it. Then, he needs to re-install a correctly sized fusible link back into your wiring. Hopefully, that will solve your problems.

dmruschell

The fusible link did blow, and the first mechanic replaced it with another fusible link, but he also rewired where the electrical fan drew power. We think that having them draw power from the starter put an excess load on the wire going from the alternator to the starter and could have caused it to melt. Or my interpretation could be completely wrong.

Either way, the mechanic it's with now is the one that works on all my cars (61 vette, 72 buick, and my 79 vette) and even designed and built the 500HP rebuild on my 79. I trust him completely. He's replacing the fusible links with actual fuses (in his experience, some fusible links can actually catch fire... and on my car the links didn't blow even when the wiring was on fire), running some thicker wires (like they started doing in '81), putting in a bigger battery, and trying out the 85 amp alternator the used in 81 rather than the 140 amp one I put in. He's also checking all of the wiring before and after the point at which it melted to make sure he only uses what hasn't been damaged (replacing the fuse box attached to a new wiring harness through the firewall to keep that clip is a big job, so he's going to solder the wires together and do away with the clip to save me a big chunk of cash). Once it's all back together, then he's going to troubleshoot why the fusible links blew in the first place. He was awarded "Best Technician in the Nation" multiple times when he worked for GM (Chevy, Buick and Pontiac) and he's lived up to that reputation consistently.

dmruschell

Forgot to mention something kind of cool that happened. My 79 has every piece of documentation that ever came with it, including the original order sheet from the dealer. Well, my mechanic and I were looking under the car when it was up on a lift yesterday and he finds an old wrinkled piece of paper sitting on one of the exhaust pipes. After teasing me about having a bunch of crap all over my car, he takes a look at it and says "oh look, there's your build sheet!" the top half is pretty unreadable, but the whole bottom is readable. Anyways, just figured I'd share, and I'm glad we found it before it blew away on the highway!

dmruschell

The car is fixed and back together. Turns out the alternator was full fielding and putting out 400 amps, so that was the start of the electrical issues that then led to the other problems. Just figured I'd post the conclusion to the saga.