Charging system.

Asde3326 wrote:
Flat disk Fan??

Better post a pic.

Asde3326 wrote:
No power at alt battery cable. Found isolater. The pack that the 3 cables bolt to on the isolater came out of the heatsink. (I think its a heatsink) or the housing for the isolated. I'm going back to try the diode test. The alt. Has the disk type pulley, not the fan.

Asde,

First off - Listen to Mex.

Now, are you saying that the plastic block that the three cables bolt to has pulled out of the heat sink (finned aluminum part)???

If that is the case, don't bother with the diode test, it is toast and it also explains exactly what happened.....

Your coach most likely has a remote sense on the alternator. When the isolator went out, the diode to chassis fried and left that open, the alternator went to max (because it could not see what it was doing) and then the coach (house) side diode either stayed alive or melted solid and provided the high voltage (as much as 30V!) to the house side long enough to do a lot of damage.

Matt

No power at alt battery cable. Found isolater. The pack that the 3 cables bolt to on the isolater came out of the heatsink. (I think its a heatsink) or the housing for the isolated. I'm going back to try the diode test. The alt. Has the disk type pulley, not the fan.

Yes.

Flat fan

Factories fitted optional LESTEK high performance alternators in that era. Different color horse. Verify alt fan design pleas

Edit note

Retired specialist. I have rebuilt 1,000+ small case Delco alts. I really do know what I'm doing troubleshooting this... :)

Cannot check rectifier type isolator without unbolting live wires. Risky. Disconnect chassis bat neg cable and house neg cables at batteries. Use hand held meter set diode to diode check setting. Red probe on center isolator terminal then touch black meter probe to outer isolator bolts in turn. Meter readings must be .300 to .800

This will prove isolator rectifier did not fail.

Then connect negative cables at batteries.

Do you now have power at both outer terminals of isolator?

(To be continued)

Flat disk Fan?? The chassis fuses & the inline stereo fuse (the one on the red wire) we noticed we had no turn signals after it happened. The fuse box label for the blown fuses are horn & radio. I will go test the alternator now. I know where the isolater is. In the coach batt. Hold

Any chance the battery cable connections to the battery got reversed during the alternator replacement? Even for a moment?

Considering your friends phone seems to have been damaged, check the voltage when it's running before doing anything else. If it's very high then you may have a bad reg.

OK here goes:

That chassis should have a Delco 12SI. Identifiable because it has a flat disc fan not a sharp blade steel fan.

1) Which fuses blew? Chassis or house?

We need to move along so let's do this:

2) Grab a 12 volt test light the kind with a point.

3) Touch the alternator battery terminal. Does tester light?

4) If no light follow alt bat wire. Look for a square finned box with 3 bolts and heavy gauge wires bolted to it - a battery isolator.

5) We have to find out before going further.

6) The further along we get the faster the process becomes.

7) Other ways of doing this are a waste of time. Do it like a pro :)

Will proceed upon reading your report. Keep test light handy.

Replaced by who? Why not take it back?

Are ALL batteries fully charged? Put them on an independent charger. Better yet have them all tested at AutoZone.

Have you discussed with the prior owner? Probably as-is sale but could have some modifications to review. PO could give some insight.