Good morning Mike, High ohm engine ground strap connections will cause spastic and damaging alternator function. If it charges now then use a hand held load meter; -1-set idle-hold at 1,500 and note volts + amps at both battery post at no load, now load the meter and note, -2-Then from batt positive post to closest frame ground, loading and noting again, a six second 100 amp load will smoke out the weak connection, -3-Then from alternator output post to engine block, repeat above no and load test, -4-repeat from alt output to frame ground, repeat above no and load test, -5-now place load meter or test light from engine to frame ground and find voltage or light, 1 and 3 will be closely identical, though 3 slightly less due to wire distance ohm reduction, reference values that you can base the alt function and amp meter realities. 2 and 4 will help you find electrical resistance. If all above 8 test give pretty much same values within a .3 volt and 5 amp variance then you need to find flaw elsewhere. Sometimes a 10 second 100 amp load test at 3,000 may break your hidden problem, try and see if above 8 don't point to issue. If it does not charge then use a large battery charger and load both battery post then repeat and charge alt stud and engine ground, you may find resistance. Also an extra large woven ground strap never hurts! 33 years ago the Baton Rouge Volvo dealer sold me 6 defective alternators in a row for the same customer. I was the largest Volvo repair shop in town and also was paid my said dealer to do warranty work for them as they were overloaded. The 7th one worked, the owner was scamming his dealership and was putting new-defective-warrantied alternators back in stock so to make more money to finance his hydroplane racing. Of course I was the largest buyer of Volvo parts so I got stung and customer was pissed beyond belief. Year or so later when owner was busted, jailed and dealer closed, his son brought me as a guilt gift a new Volvo cylinder head in crate and other parts so to make amends. Poo-poo occurs. Back in March prepping for Amelia, I noticed where my Mangusta had electrical burning marks on the alloy around the large bell housing bolt washer interfaces, WTF???, we found the bolts not to be as tight as they should have been. So my alternator engine ground was trying and having a difficult time getting back to the true body-battery ground and left burning-jumping marks on the bell housing. Now all is fine and battery cable temps are cooler. Good luck, Jeff Jeff Cobb- I pad W-225-343-7525 C-225-907-4514 On Oct 2, 2016, at 11:11 PM, Mike Drew via DeTomaso <detomaso@server.detomasolist.com> wrote:
Hi guys, Just got home from a terrific weekend in the Sierra foothills; 24 Panteras (of the 36 scheduled) took part in the Niello concours at Serrano. It heaved down with rain for a very brief period, but that rain then turned to snow which kept the large Reno/Tahoe contingent from braving the summit. Still, a great time was had by all who attended, and we drove home in splendid sunshine. We were driving in Lori's Pantera, which has a flat firewall kit and uses a GM alternator with built-in regulator. She drove the car to Vegas this spring, and the alternator failed while we were there. At first it started acting erratic, with the amp needle bouncing around, and then finally it quit and just showed a partial discharge. Testing at the battery revealed it was doing nothing at that point. We replaced it with another one, which did exactly the same thing and failed about 50 miles from home. We replaced THAT one, and the third one has worked fine until today. But it probably only has about 250 miles on it or so. On the way home, once again, I noticed the ammeter needle behaving erratically, then it quit and showed partial discharge for many miles, then briefly came back to life and showed a very strong charge (since we had been running on battery power for awhile), then discharged again. Methinks the problem is not simply that alternators are failing, but rather that there is some sort of fault in the electrical system. As electrons are far from my strong suit, I hesitate to start diving it to it blindly. What say all of you? FWIW we've got a spare alternator we will be installing tomorrow, which almost assuredly will work just fine...for awhile anyway???? Mike _______________________________________________
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Good morning Mike, High ohm engine ground strap connections will cause spastic and damaging alternator function. If it charges now then use a hand held load meter; -1-set idle-hold at 1,500 and note volts + amps at both battery post at no load, now load the meter and note, -2-Then from batt positive post to closest frame ground, loading and noting again, a six second 100 amp load will smoke out the weak connection, -3-Then from alternator output post to engine block, repeat above no and load test, -4-repeat from alt output to frame ground, repeat above no and load test, -5-now place load meter or test light from engine to frame ground and find voltage or light, 1 and 3 will be closely identical, though 3 slightly less due to wire distance ohm reduction, reference values that you can base the alt function and amp meter realities. 2 and 4 will help you find electrical resistance. If all above 8 test give pretty much same values within a .3 volt and 5 amp variance then you need to find flaw elsewhere. Sometimes a 10 second 100 amp load test at 3,000 may break your hidden problem, try and see if above 8 don't point to issue. If it does not charge then use a large battery charger and load both battery post then repeat and charge alt stud and engine ground, you may find resistance. Also an extra large woven ground strap never hurts! 33 years ago the Baton Rouge Volvo dealer sold me 6 defective alternators in a row for the same customer. I was the largest Volvo repair shop in town and also was paid my said dealer to do warranty work for them as they were overloaded. The 7th one worked, the owner was scamming his dealership and was putting new-defective-warrantied alternators back in stock so to make more money to finance his hydroplane racing. Of course I was the largest buyer of Volvo parts so I got stung and customer was pissed beyond belief. Year or so later when owner was busted, jailed and dealer closed, his son brought me as a guilt gift a new Volvo cylinder head in crate and other parts so to make amends. Poo-poo occurs. Back in March prepping for Amelia, I noticed where my Mangusta had electrical burning marks on the alloy around the large bell housing bolt washer interfaces, WTF???, we found the bolts not to be as tight as they should have been. So my alternator engine ground was trying and having a difficult time getting back to the true body-battery ground and left burning-jumping marks on the bell housing. Now all is fine and battery cable temps are cooler. Good luck, Jeff Jeff Cobb- I pad W-225-343-7525 C-225-907-4514 On Oct 2, 2016, at 11:11 PM, Mike Drew via DeTomaso <[1]detomaso@server.detomasolist.com> wrote: Hi guys, Just got home from a terrific weekend in the Sierra foothills; 24 Panteras (of the 36 scheduled) took part in the Niello concours at Serrano. It heaved down with rain for a very brief period, but that rain then turned to snow which kept the large Reno/Tahoe contingent from braving the summit. Still, a great time was had by all who attended, and we drove home in splendid sunshine. We were driving in Lori's Pantera, which has a flat firewall kit and uses a GM alternator with built-in regulator. She drove the car to Vegas this spring, and the alternator failed while we were there. At first it started acting erratic, with the amp needle bouncing around, and then finally it quit and just showed a partial discharge. Testing at the battery revealed it was doing nothing at that point. We replaced it with another one, which did exactly the same thing and failed about 50 miles from home. We replaced THAT one, and the third one has worked fine until today. But it probably only has about 250 miles on it or so. On the way home, once again, I noticed the ammeter needle behaving erratically, then it quit and showed partial discharge for many miles, then briefly came back to life and showed a very strong charge (since we had been running on battery power for awhile), then discharged again. Methinks the problem is not simply that alternators are failing, but rather that there is some sort of fault in the electrical system. As electrons are far from my strong suit, I hesitate to start diving it to it blindly. What say all of you? FWIW we've got a spare alternator we will be installing tomorrow, which almost assuredly will work just fine...for awhile anyway???? Mike _______________________________________________ Detomaso Email List is not managed by POCA Posted emails must not exceed 1.5 Megabytes DeTomaso mailing list [2]DeTomaso@server.detomasolist.com [3]http://server.detomasolist.com/mailman/listinfo/detomaso To manage your subscription (change email address, unsubscribe, etc.) use the links above. Members who post to this list grant license to the list to forward any message posted here to all past, current, or future members of the list. They also grant the list owner permission to maintain an archive or approve the archiving of list messages. References 1. mailto:detomaso@server.detomasolist.com 2. mailto:DeTomaso@server.detomasolist.com 3. http://server.detomasolist.com/mailman/listinfo/detomaso