ISB Won't Start

[chasfm11]

Symptom: turning the ignition key on lights up the driver's panel. Turning the key to the start position yields no additional results - starter never engages. Flipping the aux start switch with the ignition key to start and the engine fires immediately. Drove 200 miles home afterward with no sign of problems. At the end of the trip (and turbo cool down), I turned the key to start and the engine fired immediately. Waited 5 more minutes and the engine wouldn't start. The problem just started this past weekend. We've had this coach 3.5 years and it has never had a starting problem of any kind. The batteries are dated Nov '03

I've removed both batteries, checked the water levels (full) and then took them to be tested. During removal, I looked at all of the connections and didn't see any obvious problems. Both were fully charged and tested fine under load. I have them sitting on the bench and they are both holding 12.66 volts for over 24 hours.

I'm going to re-install the batteries tomorrow after cleaning every connection and coating everything with dielectric grease. I'll see if she starts then. If not, a friend advised me that it could be the contacts in the solenoid and that the house battery connection may come through a different path in that solenoid.

Does anyone else have any other thoughts?

[chasfm11]

Symptom: turning the ignition key on lights up the driver's panel. Turning the key to the start position yields no additional results - starter never engages. Flipping the aux start switch with the ignition key to start and the engine fires immediately. Drove 200 miles home afterward with no sign of problems. At the end of the trip (and turbo cool down), I turned the key to start and the engine fired immediately. Waited 5 more minutes and the engine wouldn't start. The problem just started this past weekend. We've had this coach 3.5 years and it has never had a starting problem of any kind. The batteries are dated Nov '03

I've removed both batteries, checked the water levels (full) and then took them to be tested. During removal, I looked at all of the connections and didn't see any obvious problems. Both were fully charged and tested fine under load. I have them sitting on the bench and they are both holding 12.66 volts for over 24 hours.

I'm going to re-install the batteries tomorrow after cleaning every connection and coating everything with dielectric grease. I'll see if she starts then. If not, a friend advised me that it could be the contacts in the solenoid and that the house battery connection may come through a different path in that solenoid.

Does anyone else have any other thoughts?

[Hooligan]

Charles: My 90 Cruise Master sometimes required using the aux battery to start, the ground connector was not making good contact on the chassis negative battery post. Pinch bolt was tight but the connector wasn't. Symptoms were as you describe.
I had the solenoid replaced on my ISB in January 05. Symptoms were just numerous tries to get the starter to engage. Using the Aux battery had no effect. Took the starter to local Auto electric --he replaced solenoid, disassembled, inspected and lubed starter, $55 total.

Hopefully cleaning the connections as you plan will resolve the problem.

[chasfm11]

It's fixed. I put the batteries back and started to methodically clean up the top and bottom of every wire lug. I put the wires on the negative terminals on both batteries and then put the positive leaves on the #2 battery. Everything was fine. When I separated the wires for the positve terminal on the #1 battery (I had tied them together with string when I took them off to keep things from getting all mixed up), I found large deposits on the underside of two of the leads. I clearly remember that terminal nut being tight, having checked in periodically over the last several years. What happened was the lugs were not tight flat spot to flat spot. That left gaps between them. I had to pry the deposits off with a screwdriver.

Lessons learned:
1. Always use the bright work light when working under the bed. The ambient light there just isn't good enough even in bright sunlight outside to really see what is going on.
2. Physically remove the battery wires once a year. I'm positive that this bug was generated when the batteries were replaced in Nov '03 and if I had removed the wires instead of just checking the nut for tightness and cleaning the visible area, I would have prevented this problem. I've updated my PM list accordingly.