Melted battery Terminal, starter wiring confusion, HELP!?

[Ryologic]

Hi everyone, me and a friend of mine just finished a clutch job on my 1983 944, and when we went to start her up, the positive battery terminal melted, and there was an unhealthy amount of smoke from the battery. Both battery wires were really hot.

We think we may have wired the starter incorrectly, does anyone have pictures of the starter that shows exactly where all the cables go? including the ones that go to the clutch bell housing or anywhere else.

Worst case scenario, what did we break? I'm kinda scared here.

[89-944NA]

you should only have three wires, 2 large ones go on the large diameter post on the starter solenoid, one small one in the small post. Worst case? Starter, cables and battery are toast.

If you wired it up correctly at the starter, make sure you put the cables on the battery correctly, not reversed. If that's ok, check the whole starter harness for cracked insulation that has caused the inner wire to ground to something.

Check Clark's Garage Home Page for proper starter installation. There is a picture of the starter connections on the starter page.

Disregard where it says to install the heatshield to the negative post of the starter....it installs to one of the winding housing bolts...those are the two bolts you see in the picture at the back of the starter, not over where the wires are.

[mikepellegrini]

There are three wires going to the starter - 2 larger ones and one small one. The small one goes to the solenoid and then back to the ignition switch (or DME). The largest wire goes to the hot terminal on the battery. If I remember right, the other larger one goes to the alternator.

My 83, the main ground strap is connected directly to the firewall (inside the battery box). On the engine side of the firewall in the middle above the sensor bracket, there's a connector block with another grounding strap which goes to a bolt on the bellhousing.

It'd be difficult to hook these wires up incorrectly because they fit only "just so."

Is it possible that you had the main wires into the starter hooked up correctly, but at an angle, so that when the engine turned over, the torque cause the connector to contact the firewall - creating the short? I had that happen once on my 951 - sorta. If you really got on it (torquing the engine over), the thing would short and the engine would cut out.

If there was a big short at the starter, you oughta be able to see evidence of it.

[xsbank]

If you didn't tighten the cables properly you would get heat and smoking like you have described...

[Ryologic]

Originally Posted by mikepellegrini

There are three wires going to the starter - 2 larger ones and one small one. The small one goes to the solenoid and then back to the ignition switch (or DME). The largest wire goes to the hot terminal on the battery. If I remember right, the other larger one goes to the alternator.

This is definitely right. Both big wires go on the same post. At least this is the way it's set up on my '83

It turns out we wired it correctly, but (we think) the battery got messed up somehow in the two weeks we had it on the stands. I thought we may have burned up the computer, but it's fine.

What we ended up doing was going to the store and borrowing a defected battery that they couldn't sell. The battery was perfect, but the case had a dent and that's enough to pull it from the shelves apparently. The defected battery didn't have enough CCA to start the car, but it was enough to check everything was ok (starter turned over, lights came on, etc) and make sure it wasn't going to go fukushima on us again.

The scary part is literally all we did was change the battery and it worked. I have no idea what happened to the old battery, because it worked perfectly two weeks ago and all it did was sit there in the meantime.

Thanks for all the replies!

On a side note, far be it from me to question the mind of Ferdinand, but who hooks a BLACK wire up to the POSITIVE battery terminal?...

[Ryologic]

P.S. According to mark, watching a battery terminal melt is a truly humbling experience.

[POPS 83 944]

Just a thought, you didn't pinch a wire between the the block and the bell housing when you reassembled the clutch? That would give you a direct positive to ground causing what you described.

[89-944NA]

Like I said in my previous post, carefully check that wiring harness. It's old and stiff, and if the insulation has cracked or fallen off in some area, it's going to short again. Maybe not today, maybe not tomorrow, maybe not for quite some time, but Hiroshima is just a start away if that harness is shorting.

Next time you may not be so lucky and ZAPPPPPPP there goes the battery, starter, wiring harness, DME or any combination of the above. Ever cleaned up the mess after a battery has exploded? I did, thankfully it was in a Ford Escort.

[Ryologic]

Originally Posted by POPS 83 944

Just a thought, you didn't pinch a wire between the the block and the bell housing when you reassembled the clutch?

Yes. That was the red/black wire that goes from the starter to the computer (I think?). In a glorious display of ineptitude, I pinched it between the starter ring and the new pressure plate while installing the new PP bolts. (That will teach me to pay attention) That was resolved long before the battery was reconnected though.

Originally Posted by 89-944NA

...Hiroshima is just a start away if that harness is shorting...
...Next time you may not be so lucky...

I will scour it. This car is going to be my DD so I really can't afford that.

[89-944NA]

If you find a break, replace the wire, don't just tape it up.

Also, you can order this sleeving from McMaster-Carr to resleeve the new cables, the starter harness I made looks like a factory harness with this (and it will protect the cable if it rubs on anything).

www.mcmaster-carr.com

Top left of the page, enter 1508T36 and hit find. I bought 15' so I would have extra if I needed to do another harness. Get 10 ft, more than enough and will cost you under $20 shipped.

[Bonecrusher944]

i just had a very similar problem with my Porsche 1989 944 S2 race car after installing a new clutch. Initially the car was running and then quit running at all on the racetrack. There was a little smoke coming up from the shifter boot. Turned off the kill switch and towed the car back to the paddock. Then the car started and ran, but was intermittently cutting off in hard left turns. BOTH the battery and alternator wires had worn thru the insulation and were resting on the bell housing. It was impossible to see any problem at all, until the wires wire taken off the starter and pulled away from the bell housing. There was an inch and half of exposed wire resting on the bell housing with 70 percent of the wire worn away on BOTH wires. it was amazing the car started and ran at all. Battery was also draining overnight for some time. Prior to changing the clutch, the car was shutting off only in hard right turns at Sebring. It seems changing the clutch did not create the problem, but after 25 years, there must have been some exposed wire on the bell housing for some time. Hope that helps clear up another 944 Gremlin.

[Trevorlw]

When you take something apart, mark it with tags if your unsure. Don't try it until you ask.
Bad Electrical will deffinatly kill wiring/melt/smoke/ = Fire = BuhBye Car. = Kaboom

[ernie9944]

Originally Posted by Ryologic

On a side note, far be it from me to question the mind of Ferdinand, but who hooks a BLACK wire up to the POSITIVE battery terminal?...

Can't see how you could get mix up in between positive/negative cables on a any 944s/968 even if they're both black.Since the ground cable is one solid cable with no other wires attache to it & is to short the reach the positive battery pole. 944
968