[Roboman]

As an FYI: 

This is the warning sign that your alternator to starter harness insulation has failed and needs to be replaced ASAP. Part number is 944 607 029 01. Until replaced, park it in neutral with the ebrake on.

http://www.968forums.com/topic/16302-fai...nsulation/

Mike/TDG I just want to check with you as to which cable(s) you replaced, because the gauge of the one I received isn't as heavy as that of the one in the thread quoted (I don't think). ... also looking at the wiring diagram in that thread....


I've bought cable xx02901 and can see that if that shorts the leads to pre-engage solenoid on the starter then that may trigger the solenoid and, I think, the starter will rotate.... so I think that's the potential criminal here, but want to check. It is the one you circled in red??


I'm not sure the starter cable can cause the same problem but don't have time to check ..... If the battery to starter cable shorts then that'll put the battery direct to earth and weld the cable to the chassis.


So Mike/TDG .... would you please use the diagram in the quoted thread in order to identify the suspect cable. Thanks

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[machinist_dc]

I could if I had old OEM cables to work from.

 

I wonder if you can make cables for RHD cars?

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[machinist_dc]

That's another reason I made my own and began making them for others.  I normally use 6 gauge for the alternator to starter cable and occasionally substitute 4 gauge for those with higher output alternators or who just want a heavier cable.  6 gauge is plenty though.  The 12 gauge SGX or 10 gauge silicone-insulated wire I use for the solenoid can stand a LOT more abuse than the OEM solenoid wire which has PVC insulation.

 

My replacement arrived yesterday, it's not as heavy duty as I was expecting! Maybe next week I'll have the time to at least remove the old one and compare them ...... and do the crunch test on the old insulation!

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[968TDG]

I didn't notice the gauge of the main cable in the harness, but it was at least as big as the original cable.  The lugs looked high quality, and I was happy with the build quality.

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[Roboman]

I didn't notice the gauge of the main cable in the harness, but it was at least as big as the original cable.  The lugs looked high quality, and I was happy with the build quality.

 

Okay thanks.  I put mine up in the air this morning and then had to go to a meeting, so I'll have another/better look tomorrow.  Cheers

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[pdxmike]

Roboman - yes the red circled harness is 944 607 029 01. The image is from the 944 S2 part diagram. The LHD harness runs from the alternator to starter with a connector for the ignition switch near the brake booster. My recall is that the wire gauge was identical - only difference was the 944 part is a few inches longer however there is ample room behind the alternator for the excess to be safely secured. Interesting that your gauge appears different...

 

This said - 

 

Machinist_dc's offerings on Ebay are a superior long-term solution, as with the Porsche 944 part the design flaw remains and future deterioration of the insulation can and will cause the "ghost start" issue to recur. It may be 20+ years down the road however there remains no way to inspect the condition of the wiring with the OEM solution. Machinist_dc's design solves this issue. Machinist_dc - thanks for adding to the thread - this is a really important offering especially as the other third party sources are no longer available. 

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[Roboman]

Thanks Mike that's what I wanted to read as the wording of the other thread was a little ambiguous. By luck, well maybe, I'm also changing my brake booster, so I should get a clearer run at routing the new harness. Thanks Jack for the idea of dropping the starter. More later ....

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[Waylander]

I could if I had old OEM cables to work from.

 

When this virus madness is a bit more settled I will see what I can do about finding a RHD alternator harness, the battery is in the rear on RHD cars

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[machinist_dc]

Roboman - yes the red circled harness is 944 607 029 01. The image is from the 944 S2 part diagram. The LHD harness runs from the alternator to starter with a connector for the ignition switch near the brake booster. My recall is that the wire gauge was identical - only difference was the 944 part is a few inches longer however there is ample room behind the alternator for the excess to be safely secured. Interesting that your gauge appears different...

 

This said - 

 

Machinist_dc's offerings on Ebay are a superior long-term solution, as with the Porsche 944 part the design flaw remains and future deterioration of the insulation can and will cause the "ghost start" issue to recur. It may be 20+ years down the road however there remains no way to inspect the condition of the wiring with the OEM solution. Machinist_dc's design solves this issue. Machinist_dc - thanks for adding to the thread - this is a really important offering especially as the other third party sources are no longer available. 

 

You are welcome and thank you.

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[machinist_dc]

When this virus madness is a bit more settled I will see what I can do about finding a RHD alternator harness, the battery is in the rear on RHD cars

 

Alt/start cable should be same length though exciter and solenoid lengths should be different (probably longer).  I just shipped an A/S cable to Singapore for a RHD car.  If I had an old RHD harness or someone gave me lengths of exciter and solenoid wires, I could make them as well.

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[Roboman]

I swapped the alternator/starter harness out and it was pretty straightforward ..... however, the booster and inlet manifolds are off and so I'm aware there's additional space.  I think my comment is mainly about the space under the car if you're working with axle-stands (I won't under the car with just a jack).

 

The simplest thing was to drop the starter.  It's easy to access if you just jack up one side so that the bottom of the car is leaning towards you, and when you put the starter on the floor you can have a good look at the cable angles needed when mounting the new harness (there is an hour-glass shaped piece of plastic as a guide for the cable ends).

 

So I recommend releasing the alternator cable end first, cutting/releasing all the cable ties/holders, and then releasing and lowering the starter motor with the old harness still attached.  Drop the new harness in from the top along what you think will be the final routing, and then you dive (or in my case, stagger) underneath to swap over the starter end of the harness.  Remount the starter, and then work your way from bottom to top reattaching the various ties.

 

I've not yet reconnected the alternator as I've not yet remounted the booster and inlet manifold; once they are in place I'll be more aware of the final routing.

 

I hope this helps.

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[dlearl476]

I have a question for the brain trust: My battery finally died after 2 attempts to resurrect it from dead. It would charge ok, up to 13,5V, but after running the car for a bit, it wouldnt start and voltage had dropped to 10.7V.

Worried that my alternator was toast, I charged it again and drove it for ~45minutes, the ammeter was >12V the whole time but I pulled into Batteries+ and had them load test it: NFG

So I bought a new battery and put it in, and on the ensuing drive ammeter never got above 12.5V.


From what I remember, after sitting for a month or so, my Ammeter would read close to 14V. Is it only reading 12.5V because its a fully charged battery or should I look into it?


Im getting my belts done next week, so if I need to replace a regulator or alternator, now would be an ideal time to do it.

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[Waylander]

I would start with the cheap option, the brushes have probably worn away on the regulator,


I can buy perfectly good regulator here in the U.K. for about $10

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[ds968]

Yup, cheap and fairly easy to replace, so it’s a great “nothing to lose” troubleshooting test.    Had my regulator replaced twice .   

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[snova]

dlearl476,

 

Been there done that.   Had similar situation as you.   Battery cell failed.  Eventually alternator died.   Voltage regulator didn't help. 

I wouldn't order a regulator online.  O'Reillys can get it to you to a local store, in case it doesn't work and you need to return it. 

Shipping it back would be a pain.

 

I've replaced many alternators and I've come to the conclusion that don't try to buy a remanufactured one. Find

a local business that rebuilds alternators. That will be the best and most reliable result. 

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[dlearl476]

Sadly, our last old school auto electric place closed last year. Luckily, I had them rebuild my Beck starter and alternator before they did. So its reman or new for me.


BTW, is anyone currently driving their car? Whats your ammeter read. Ive had zero issues with the new battery, and Ive put enough miles on it that if the alternator wasnt charging, it would have manifested.

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[dlearl476]

dlearl476,


I wouldn't order a regulator online.  O'Reillys can get it to you to a local store, in case it doesn't work and you need to return it. 

Shipping it back would be a pain.

  

At $18 vs $54 @Rock Auto or $139 at Pelican, Ill just keep it for a spare if I need an alternator.


Woops. Spoke too soon. I guess the seller cancelled my order. Must have been an old link.

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[ds968]

Even with a new battery,  if the alternator is not charging at all , you’d be lucky to get 50 miles worth of driving .  If it’s charging a little but materially insufficient, maybe a few hundred miles, but that’s a stretch .  And it would definitely manifest itself in one way or another, weakened batteries have a way of messing up a lot of functions .   

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[Waylander]

https://www.woodauto.com/product/VRG4641


This is less than $10, have one in my car works fine

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[dlearl476]

I had to bite the bullet and get a more expensive one ($49) AZ Autohouse was the only place that would get it here before my appt without accelerated freight. But the good news is that its an OEM Bosch one.

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