question on 8V71 starter motors

[bevans6]

As some may recall I am in Halifax on a bus trip, and we were walking around the historic waterfront area this morning when I saw a really familiar looking bus.  MCI MC-5C, and it looked just like the old Banff tour bus that my friend Carl has in his back yard, with the same faded lettering and the tour bus windows in the roof.  So I wandered over - a bunch of musician kids from my neck of the woods in Ontario had bought one of Cherrey Bus Lines old 5C's, originally from out west, and were in town playing at a local bar.  They had electrical issues - probably more than one, but the big one  was no action from the starter motor.  I tried to help a bit, was able to determine that it was almost certainly the starter solenoid, but they had a local friend with a contact at a local bus charter company so they were off to visit the bus doctor and hopefully get a house call out of him!

It started me thinking - on a typical 8V71 starter, does the solenoid just switch current to the motor or does it also move the pinion gear into place?  Some starters that I have worked with have an inertial pinion - the rotation of the motor throws the pinion into mesh with the ring gear, and some have a lever action from the solenoid that actively moves the pinion into mesh.  The question comes from this - if you had a bad solenoid with the inertial type pinion motor, you could jump the terminals with a screwdriver and start the engine.  If you did that with a the other kind, all that would happen if you jump the terminals is the starter motor would spin, but the pinion would not engage.  Any ideas on this?

Thanks, Brian

[JWallin]

They didn't accidentially bump it into gear, did they?

[luvrbus]

Brian,the solenoid engages the bendix drive on the stater if you jump the cable terminals the stater will spin,jump the small terminal below the battery cables it will spin and engage the starter that is if the starter is ok


good luck

[Ncbob]

Since I recently had to have my own starter rebuilt I feel qualified to answer your question. Unlike a Ford starter which spins and inertia throws the drive gear into the ring gear the Delco starter depends on the solenoid to lever the drive gear into the ring gear and the plunger in the bottom of the solenoid passes current to the fields and cranks the engine. I can also attest to the fact that I only want to replace that dog once in my lifetime. It's one heavy brute!

NCbob

[kyle4501]

Better use a big screwdriver if you're gonna jump the terminals. I used a medium sized & it turned red & melted before I could react. 

That was an interesting trip!

[Ed Hackenbruch]

Use a broken or junk one or maybe a piece of rebar.

[jackhartjr]

Kyle said, "Better use a big screwdriver if you're gonna jump the terminals. I used a medium sized & it turned red & melted before I could react. 

That was an interesting trip!"


Yeah my eyes got big!
  And yes, it was an interesting trip!
JAck

[kyle4501]

Kyle said, "Better use a big screwdriver if you're gonna jump the terminals. I used a medium sized & it turned red & melted before I could react. 

That was an interesting trip!"


Yeah my eyes got big!
  And yes, it was an interesting trip!
JAck

Yep, the melted screwdriver was right before the woman with the pit bull got there. . . .
If I had a gun, I would have shot that bitch & let the dog eat her.

[TomC]

Goofin with crossing the terminals is a chancy thing.  Consider this-my truck has 4-31 Interstate batteries that are 950CCA each, or around 1100CA in 70 degree weather.  That's 4,400 amps of power at 12VDC, or about 70hp of electricity!  Just thought I'd put it into perspective.  Good Luck, TomC