Yikes! Starter piece melted!

[jtexfisher]

K5 ('79, 400sb) wouldn't start yesterday. Pulled the starter and found that the copper buss that carries current to the starter windings was MELTED PLUMB IN TWO! Anybody seen that b4 or have a guess as to why?????

Thanks, JTEX

 

[diesel4me]

never saw that before..

I'd say it was either due to a loose connection to the solenoid,or something put a real strain on the starter and got it hot enough to melt it--I'd say arcing due to a loose connection is probably more likely--or maybe a dead short in the starter windings ... did it melt right at the screwhole that bolts it to the solenoid,or in the middle of it??..

 

[jtexfisher]

My guess is arcing too. Been having a heck of a hard start time lately. Replaced the solenoid today. HOPING this is the end of the hard start/no start episodes for now!

 

[R72K5]

make sure there is sufficient ground(cables- condition and guage)) and that all cables are tight and clean

 

[jtexfisher]

Irony of ironies, that's just what I've been up to. New batt., new cables, cleaned and shined all the places where cables connect. Each and every one of 'em. PO had the motor out and didn't do such a bang up job of reconnecting braids to frame, body, etc. Those what where connected were filthy and/or connected to painted metal. But gremilns get loose when you fix grounds. Mabye it make's 'em mad?

Solenoid question? Big copper "ears" stick out of the starter near the end (opposite the gear) and connect to the bolt that is the "other half" of the BATT (hi current) connection. A screw and a copper "pipe" make the connection from BATT to the starter "ears". Should the screw be insulated or just installed? Never put a solenoid on a starter before, they've always had 'em on when I purchased one. Pardon the high tech terms like "ears" and "pipe", but I just dunno how else to describe 'em.

Thanks for the quick replies!!!!!

jt

 

[Kiwi John]

Starter probs

Could be high current flow caused by worn brushes inside starter motor.
Could be loose connections, but now you've fixed all those.
And could be a mechanical load causing high current flow such as:satrter motor mounting bolts loose; Ring gear &/or pinion gear worn; bearings on commutator shaft at each end of starter motor could be worn or binding > high current flow. If bearing at pinion end is worn then pinion gear will go out of line when trying to turn engine over, bind a bit, and draw excess current again.
Any of these can also cause your wiring to burn at the weakest point.
Would be worth having starter motor out for refurb if it's old or been under water at all?

 

[HarryH3]

Solenoid question? Big copper "ears" stick out of the starter near the end (opposite the gear) and connect to the bolt that is the "other half" of the BATT (hi current) connection. A screw and a copper "pipe" make the connection from BATT to the starter "ears". Should the screw be insulated or just installed? Never put a solenoid on a starter before, they've always had 'em on when I purchased one. Pardon the high tech terms like "ears" and "pipe", but I just dunno how else to describe 'em.

Thanks for the quick replies!!!!!

jt

The "copper pipe" is the conductor between the solenoid output and the starter motor. The screw keeps the copper pipe in contact with the "ears". No insulator needed, as the screw also becomes part of the circuit.

 

[Roz]

i say check the winding before u install it, could be shorting as kiwi john said. would have to see the sorting to help visually. i like to tourque mune and spray batt sealer on it- not that it functionally does much. but i think it help with bi-metalic corosion

 

[savagek5diesel]

actually that happened to me a couple days ago.

the other day the same thing happened to me, and it was because it was a little bit loose and the bendix gear got stuck on the flywheel, but wasn't turning the engine over while i was trying to start the truck.

 

[wasted wages]

Ihave seen the light,,

I have seen the light and it is good,,,,,




This will cure all your starter ill's,,,,





http://www.gmgoodwrench.com/perfparts/images/parts/large/12361146_large.jpg

 

[jtexfisher]

Thanks, excellent stuff.

Good news is the copper bus is still intact.
Bad news is the K5 has sat in town since Thursday.

History: I've removed the solenoid and measured the clearance between the flywheel teeth and the starter pinon, no combination of shims, or use of just outer shims will bring the starter to the proper (measure: 1 paper clip) clearance. Finally landed on a single 1/32" outer shim which gives the tightest engagement of the starter gear/flywheel. Still nowhere NEAR the 1 paper clip, but starts and doesn't make TOO much noise.


NOW.....

The starter/ring gear won't get together anymore. The truck started fine, although a bit noisy, and off to town I went. Hopped back in the truck after doin' my stuff, and now the starter just hits the tip of the teeth on the ring gear. TALK ABOUT NOISE!!! It's like the starter or the ring gear/flywheel/flexplate (pick a name, every name's a winner ) moves after a start or two? Driving me NUTS!!!

 

[HarryH3]

Look closely at the ring gear. They will sometimes have bad wear in just an inch or two of the ring. When the engine stops with those worn teeth in front of the starter, then the teeth can't engage.

 

[Roz]

pull the pullys to move crank a bit then try it, might be what harryh3 said

 

[jtexfisher]

Many, many thanks

I'll give that a try (rotate the motor a few degrees and see if the starter engages)


THANKS AGAIN!!!

 

[diesel4me]

Bad teeth....

Yes,like Harry said,there is likely 4 spots on the flexplate that the teeth are worn(its where the compression strokes in the engine are,and the teeth take a beating there more than the other areas on the flywheel)..bad bushings in the starter nose can cause the clearance to change too,as can a hairline crack in the nose,that only "spreads" while cranking..

My 400SB I had ate more starters than ANY of my other trucks,and I never knew why!--but after I pulled it out of the truck before I junked it,I noticed it had about 1/8" or so of "end play" in the crankshaft!--it never made ANY noises or knocks either,and I drove it a LONG time!-(never checked that when I put the motor in!--might have ALWAYS been that way! )---maybe that was the reason the starters seemed to die young--most of them had bad bendix,that refused to engauge when it dropped below 30 degrees,for some strange reason--one guy said it was motor oil getting in the bendix from a leaky rear main seal. --it had a slightly bent flexplate too--it was the only 400SB one I found used that was useable,and I never bothered to buy or install a new one...