Starting problems culminating in a spark in the tunnel

[MikeJW]

My 1974 lightweight 24v daily driver has started to exhibit strange behavior on starting over the last couple of weeks. 50% time it's a strong starter, no problems. 25% it's slow, feels like a discharged battery. 25% completely dead, just "click". If I roll the truck a couple of feet (out of gear) it tends to start. This morning when I turned the key, there was a white spark in the tunnel area, looked to be around the 4wd selector. (The inside of the cab is bare metal floors & tunnel) Next time I turned the key it started fine. I've checked for loose connections in the starter circuit and for stray wires around the bellhousing area but there's nothing obvious. Any ideas on what to check next?

[SafeAirOne]

Check battery cables (remove and clean contacts, both positive and both ends of the negative wire). Do the same with all the grounding straps between the chassis and engine and chassis and body.

The electricity is having to find its own way back to the battery because of poor contacts.

[Howsomever]

I would agree with Mark.

Clean, bright and tight

[mearstrae]

Sounds like a ground issue. Does it only happen on start-up? If so, follow the advise of Mark. When I redo these I put a metalliic anti-sieze on my grounds (earths) and dielectric grease on my positives, after cleaning all contact surfaces, this prevents corrosion and provides a good connection.

'95 R.R.C. Lwb
'76 Series III Hybrid 109
'70 Rover 3500S

[gudjeon]

The starter is not grounding properly. Run a braided cable from the engine, as near to the starter as you can, to the chassis. If you can attach it to a starter mount, even better. It is not uncommon with corroded connections as the high amperage draw of the starter needs to ground. In some cases, it can ground through gears and bearings in the transmission. I have seen cars ground out starter draw through speedo cables and clutch cables. A ground strap makes an obvious and easier path to carry high current to ground. It doesn't even has to be insulated. A thick flexible braid like so:

[MikeJW]

Well I took another look at the leads and cleaned and tightened a couple of ground straps that had worked loose. Started first time. But next time I tried to start it, only got a click then smoke from the starter motor. So I'll pull it, probably over the weekend. Any tips for testing it? Can they be rebuilt as a 24v starter is not cheap or easy to come by.

[4flattires]

Anything can be rebuilt, including that starter. I know a great shop in Phx, AZ if your up for the freight both ways.

[Partsman]

What state are you located in Mike? That might help folks here put you in touch with a rebuild shop. There's a good place here in Massachusetts, but again, there might be one right around the corner from you, so why pay freight if you don't have to.

[MikeJW]

Burlington VT, there are a few specialist shops locally so I'll try them 1st.

[Partsman]

That would be the best bet, if you happen to know anyone in your area that works heavy construction, they might even be able to give you a recommendation of one over the others, as the starters and alternators for dump trucks and tractors are extremely expensive, so people in that industry tend to have them rebuilt rather than replace them. That's how I know the specialist shop in my area, my family did asphalt for nearly 7 decades, we always rebuilt rather than buy new, buying was always a last resort when we had no other choice.

[MikeJW]

After taking the starter apart I found the thread was stripped on the ground terminal on the starter, so when it was tightened it was turning the wire that connects to the field coils and snapped the wire, so there was only touch contact. So I'm off to get a new terminal soldered in.