rgs944

Pic of corner of oil pan where it was arching. It is hard to see but look right in the center of the pic

After looking at the pan again the pot marks I see are in a few other spots on the aluminum pan so maybe they are not arching spots. I am certain about the starter feed wire that rubbed bare in that area.

rgs944

I peeled back the red plastic and you can see where it rubbed into the starter feed wire from the corner of the oil pan.

Ducman82

ouch!
but fixable.

rgs944

This is a pic with the loom opened up. You can see the flat part where the starter feed wire rubbed bare. I am sure this would be a good thing to check next time you are under your car.

depami

And maybe a reminder not to hit the starter with a hammer.



Glad you found the problem and no major damage was done, like under hood fire.

rgs944

Tapping on the starter had nothing to do with it afterall. This problem might have been brewing since the car was new and it finally wore the wire bare. I did reach under there and see if the starter wire was loose and that likely had more to do with it than anything. It will be interesting for people to chime in to see if anyone else has seen this before. It is a hidden area so I really think this is something that needs to be checked.

j.kenzie@sbcglobal.net

Hi Rob,
I am glad you found the root problem. I agree that the hammer probably had nothing to do with it, but maybe reaching or pulling put pressure on the big wire from the battery to the starter to the alternator. I am sure it was brewing for a long time, but it did not fail until it did so explosively under your own eyes.
The big red wire you show is the cable between the starter and the alternator. The big black cable goes to the battery. I mention this because the red cable is very easy to replace with standard 2 or 4 gauge battery cable seen in auto parts stores. I sistered just such a cable onto my car when I upgraded my alternator. I also ran the same heavy cable from the alternator to my jump post. I seem to remember being afraid of shorting to ground, because I wrapped my cable with a length of fuel hose as a cushion where it was close to the oil pan and cross member.
Good luck,
Dave

jcorenman

I am glad you found it. You are also lucky that it wasn't one of the big wires.

What I am not getting, however, is how it was rubbing on the oil pan. That harness runs over the top of the cross-member, outside the engine mount and secured by a clamp (impossible to reach but hopefully back in place after a MM job). Then it joins the main battery cable and is clamped to the back of the crossmember, which should keep it well away from the pan. Then it does a U-turn to the starter. Both harness and main battery cable are protected with heavy rubber tubing, and there is also an extra piece of rubber insulation on one of the pan ribs, and on the lower edge of the crossmember.

Here's our '88 S4, ignore the GB cosmic clutch hose. You can see the harness entering from the left, from above where it is clamped to the top of the crossmember. It is in rubber tubing (the brown is original cosmoline), and clamped to the crossmember, with the main cable (also in rubber) above it. You can also see a bit of the extra rubber on the crossmember-- directly below (in this view) the starter motor.

This is a car that I've owned since new, this is how the factory had the harness arranged. I don't think there is any way that the harness can get to the oil pan-- even when the mounts were collapsed, there was still good clearance.

But clamps and stuff can get left off over the years, so checking is certainly good advice.

rgs944

Jim, it will be a few days before I get the car up in the air again to look but you are likely right. Something probably got left off or mis-routed over the years.

Bill Ball

Jim beat me to it. The proper routing and clamps should have prevented this. Look carefully at Jim's pic and you will see the clamp is on the red sheathed engine harness which shorted in your case. The red sheathed engine harness routes below the black battery cable. Jim has a few extra tie wraps, which can't hurt, but I think there were a couple of them holding the black cable and red engine harness together from the factory. I've seen all kinds of loose cables in this area in cars that have either had the motor out or the motor mounts replaced.

rgs944

I will be working on the car next week and hopefully I have everything that I need coming from 928 Int. I am confused on where the injectors and sensors get the feed from. Are they seperate from the 14 pin?. The parts I have coming are the fuse panel, the main harness that goes to the 14 pin and routes up to the blower fan/headlight area. Also I have the 14 pin harness going to the starter and alternator. I guess my main question is, are the engine fuel injector and sensor wires on the starter and alternator harness?

rgs944

Just recieved my new parts in the mail today. I feel like a kid who just opened up a Christmas present. Just knowing that the parts are here and wih the car makes me feel a lot better. I am going to put the parts by the car and hope they jump in all by themselves. If that plan does not work out I should get around to wrenching on it by Thurs. We have a Kubota engine project that takes first priority this week.

rgs944

All the parts look very good, Thanks Mark and Tom at 928Int.

Mrmerlin

you should know this but worth repeating,
disconnect the battery before you attempt any electric repairs.

rgs944

Yes, thanks Stan, It was actually a mad rush to disconnect the battery at the time of the incident.