Starting Problems with an 84

[Charlie Kile]

I bought this Touring Optioned Coupe, RQB3921, from Dan Booth in 1998.

Every few months it wouldnt start.The voltage would drop to zero when the key was turned then show 13 volts when released. Eventualy it always started. But It would never do it, nor could I duplicate it, at home.

I switched out the engine in 2007 and went to a serpentine belt set up. I replaced all the accessories with new except the starter.

Everything was good till about a year ago and it started the same thing all over!

As I backed out of my garage a while back I forgot some thing and shut it off. Went inside to get what ever it was that I had forgotten.

When I went to start it it wouldn't start. Finally it happened at my house where I could check things out!

I got my old VTVM out and started checking things out.

Battery post 13volts,Battery post clamps 13volts, cable lug at the solenoid 13volts, solenoid post about 3volts!

Obviously a loose nut on the post. Nope it was tight. Probably carroded. This would explain why it worked so long after the engine change. So I disassembled everything.

While removing the nut from the solenoid post I noticed that it was tight all the way off.

I didn't see any carrosion but lightly sanded every thing anyway.

I also ran a 3/8x24 tap through the nut, Suprisingly it went easily so I figured the threads on the post were deformed. But they looked good.

I reassembled every thing noting that the nut still felt tight. I tightened everything snugly.

To make sure it was tight I tried moving the cable lug. IT MOVED! so I tried tightening ithe nut some more.

Didn't help.

Still moved.

So I disassembled it again. Since I have sa small machine shop and have the tools I checked the threads on the solenoid. They were 10x1 mm !

I called a starter generator shop and sure enough it needed a 10x1 mm nut which he gave me.

Seems that GM uses both sizes! Both a 3/8x24 and some 10x1mm

Charlie

Edited April 12, 2013 by Charlie Kile

[warren55]

That metric/sae hybrid stuff can be a real challenge! I'm lucky that everything (with the exception of the aftermarket A/C compressor) is sae, and everything on my Mercedes is metric!

It's nice to finally find the culprit after all this time, though.