Finally running great and then, alternator wiring fire ,recommendations Options

[Ron914]

Well I finally got my car up and running great . After the static timing I got someone to sit in the car and hold the throttle @3500rpm so I could set dynamic timing to 27 degrees . This went well and the car again never ran better since motor rebuild . I drove it a bit and then decided to install the Bursch header ( given to me by@ drem914 )after having the muffler replaced . Thanks Franz .
I need to get a bung welded in to it so I could finish the hookup of my AFR and start tuning my MPS .
I first put my rear sway bar back in with new bushings as this requires the muffler to be removed for access.
I installed the Bursch and started the car , Muffler sounded a lot better. than my original 914 muffler that I found holes in.
Decided to take my buddy for a drive to show him how great the car sounded and ran .
Made it to the corner and then proceeded down the street and when shifting from 2-3rd I heard some type of noise( maybe a crack/pop/snap ) and noticed the car losing power ,glanced up in the rear view mirror to see if anyone was behind me and a ton of smoke was coming out of the engine compartment .Immediately shut of the key and put in neutral so I could coast into the tract next to me in a panic . I thought I was going to lose my car to a fire but luckily it was an electrical fire instead of gas , what a lot of smoke though . Pushed the car back home and a quick investigation revealed the 10 ga wire in the alternator wiring harness completely melted down revealing bare copper wire that goes from the alternator to the + starter post where the battery cable attaches for charging . Any ideas or suggestions would be appreciated .
Why did this happen?
Should I replace the alternator ?
What about the starter?
The voltage regulator?
I see that 914Rubber sells a wiring harness, the three pin plug that goes between the alternator and Voltage regulator did not get much damage and looks ok to me .
I can order new charger wire and repair the harness.
Also thinking of adding a breaker , I attached a photo of what I am considering but before purchase I have learned to ask the forum first .
I must say it does not look easy to get to the alternator ,I installed it when motor was out of car . Do I need to remove the motor for access?
The way it burned it seem likely a short to ground occurred but hard to tell after the fact what caused this . I think my car is possessed , can't believe this just happened when I was so close.
Some photos :

[Spoke]

That happens from a dead short. Likely VR and starter are ok, propably even the alternator.

Did you change the alternator? I've heard of some rebuilt alternators with the bolt for that wire being too long and hitting the case. Hopefully that is your issue.

BTW, that wire is your fuse. Likely burned up and melted where the short was. I wouldn't add any breaker or fuse there.

[emerygt350]

Did it short the sheet metal? That is an area that will rub if the grommet is shot.

Sorry to hear this happened.

[JeffBowlsby]

Ron,You have the patience of Job! Sometimes it ay seem like these cars are jinxed, but you are eliminating problems one at a time.

Where the big red alternator cable passes through the tin, both at the engine shot and at the rear wall is where this harness typically fails. Heat builds up at these points and eventually deteriorates the casing and wire insulation creating a short to the tin. It’s the common failure of these harnesses. Recommend inspecting these penetration points annually.

I have new alternator harnesses built and ready to ship if you want one, and I use updated cable sizes for greater ampacity. No core charge.

[fiacra]

Ron, you may have already seen it but here's a link to McMark's article about removing the alternator while the engine is in the car. It also nicely explains, and shows, what Spoke refers to about the stud that the red wire goes on being too long on some alternators.

http://www.914world.com/specs/alternator_replacement.php

If it turns out you need a new VR let me know. I have 2 NIB Bosch VRs on my shelf that can best be described as an ode to spending too much money on parts I might need someday. One can be yours for the asking.

Get a replacement wiring harness from Jeff. You'll not beat the quality of his work.

[thomasotten]

Also make sure the new or rebuilt alternator's terminals aren't higher than OEM spec. I made a video about this, maybe it's useful.

Video - Alternator Installation Tip for 914

[Ron914]

That happens from a dead short. Likely VR and starter are ok, propably even the alternator.

Did you change the alternator? I've heard of some rebuilt alternators with the bolt for that wire being too long and hitting the case. Hopefully that is your issue.

BTW, that wire is your fuse. Likely burned up and melted where the short was. I wouldn't add any breaker or fuse there.

I have not changed the alternator ( but who knows what might have been changed before I purchased the car ). Thanks for the information . It appears to be a dead short to me also but the charge wire got so hot all the outer insulation burned off so I cannot identify where the short actually occurred .The 3 conductor cable between the Alt. and the VR look intact so I was just going to run a new wire from the Alt. to the starter and cross my fingers the alt.and starter are ok the VR looks fine .
I'll have to think about this .Might be better to just buy a new harness.
Ron

[Ron914]

Ron, you may have already seen it but here's a link to McMark's article about removing the alternator while the engine is in the car. It also nicely explains, and shows, what Spoke refers to about the stud that the red wire goes on being too long on some alternators.

http://www.914world.com/specs/alternator_replacement.php

If it turns out you need a new VR let me know. I have 2 NIB Bosch VRs on my shelf that can best be described as an ode to spending too much money on parts I might need someday. One can be yours for the asking.

Get a replacement wiring harness from Jeff. You'll not beat the quality of his work.

Thank you , That's very kind of you . I don't think my old VR is bad but I'll have to wait until I get the bad wiring replaced . My fingers are crossed the wiring is all that is bad .
Ron

[emerygt350]

Go for it. If you are watching you will see where the problem is.

[Ron914]

Also make sure the new or rebuilt alternator's terminals aren't higher than OEM spec. I made a video about this, maybe it's useful.

Video - Alternator Installation Tip for 914

Hi Thomas,
Great job with the video . I need to get the alternator removed first and then I might be able to see if it grounded out to the cooling cover . I will check my clearances first and buy a tube of RTV gasket sealer.
Thank you
Ron

[Ron914]

Go for it. If you are watching you will see where the problem is.

Thanks Emery,
I have to do a brake job on my girlfriend's Audi this weekend so a follow up probably won't come until next week .
I was so close to taking the car to the smog shop for my test .
Ron

[Ron914]

Ron,You have the patience of Job! Sometimes it ay seem like these cars are jinxed, but you are eliminating problems one at a time.

Where the big red alternator cable passes through the tin, both at the engine shot and at the rear wall is where this harness typically fails. Heat builds up at these points and eventually deteriorates the casing and wire insulation creating a short to the tin. It’s the common failure of these harnesses. Recommend inspecting these penetration points annually.

I have new alternator harnesses built and ready to ship if you want one, and I use updated cable sizes for greater ampacity. No core charge.

Hi Jeff , @JeffBowlsby
Why don't you go ahead and send me a new harness . Can I send you a check ? Message me the total and I'll send a check if that's ok with you.
Thanks
Ron

[JeffBowlsby]

@Ron914

Will do Ron, will follow up with you Sunday night.

[Ron914]

So I was able to remove the old alternator and wiring today . Looks like I will definitely be replacing the wiring and I think since this job was such a PITA and I don't want to do it again , I will be replacing the alternator also . Below are more photos of the burnt wiring and the alternator. I think I can see where the (+) charger wire first shorts on the cooling cover I added arrows marking the spots . Now I need to order some parts and will follow up when I complete the repair . I think the VR is ok since I see no visible damage .
Thanks to all that replied the advice and links were very helpful and a couple of members have already reached out with parts needed.

[DC_neun_vierzehn]

Also make sure the new or rebuilt alternator's terminals aren't higher than OEM spec. I made a video about this, maybe it's useful.

Video - Alternator Installation Tip for 914

Good stuff! Mental note made for potential future reference.

[DC_neun_vierzehn]

@Ron914 sorry you had this issue. I applaud your methodical approach to investigating the potential issues. Sounds like you're getting great advice from the community. Good luck with eliminating this gremlin.

[Ron914]

Also make sure the new or rebuilt alternator's terminals aren't higher than OEM spec. I made a video about this, maybe it's useful.

Video - Alternator Installation Tip for 914

Good stuff! Mental note made for potential future reference.

Good video Thomas does a great job describing removal and installation.
Thanks
Ron