Ignition Switch

One more step to Johnny's instructions (which you don't need since you've
taken it to the shop): Remove the bakelite cap from the end of the
solenoid. That will expose the "heads" of the cable connectors inside, and
the copper "washer" attached to the solenoid plunger. It's the washer
mating the two "heads" that acts as the battery switch. The washer and
heads will undoubtedly be deteriorated. It should be possible to turn both
bolts and washer to present new contact surfaces, yielding a "like new"
solenoid switch. Later solenoids probably have neither copper nor
rotatable components.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Sat, Dec 28, 2019 at 10:40 AM Johnny Bridges via Gmclist <

> What KenH said. However, it is possible for the contacts inside the
> solenoid to degrade. Put your meter on the 1 or 2 volt scale, negative on
> the
> large bolt strapped to the solenoid and positive on the large bolt the
> battery cable connects to. Crank, and see what the drop is. Or quick and
> dirty, take a (sacrifice-able) screwdriver and short the two large bolt
> terminals on the solenoid together. This bypasses the solenoid contacts.
> The above being said, I'd still look for a bad connection in the heavy
> battery cables, INCLUDING the ground cable to the engine block. If they're
> all
> tight and shiny and the screwdriver trick doesn't get a start, and theirs
> 12V at the solenoid, now you're justified in removing the starter. Which if
> you do, simply renew the front bushing and rear bearing and brushes, and
> clean up the armature and undercut the mica between contacts on the armature
> just a bit with a piece of fine tooth hacksaw blade. Score the side of
> the case into both the rear and nose pieces so it goes back together in the
> same orientation it came apart. Stoddard solvent (mineral spirits) and a
> brush will clean it up before reassembly.
>
> --johnny
> --
> Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> I forgive them all, save those who hurt the dogs. They must answer to me
> in hell
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Ken,

I could not follow where he was measuring 7 or 6.2 volts at and how he was following a logical approach to towards diagnosing the problem. So I quit
posting.

Was the voltage measured at:
the battery,
the heavy cable at the boost relay,
the heavy cable at the solenoid,
the jumper between the solenoid and the starter,
or maybe at the small terminal on the solenoid going back to the ingition switch through the neutral safety switch.

Considerations for the ground side return to the battery are not in the above list.

Other questions are does the solenoid click when he turns the key to start and do the headlights dim?

Without at least some of the above answered, everything here is just a guess.

Ken B.

> Melmull,
>
> You've asked at least a couple of times whether the starter switch could be
> the cause of your low starter voltage. Despite all the good information
> that's been provided, no one has explicitly answered that important
> question. My answer is NO. The only function of the starter switch is to
> provide current to the solenoid on the top of the starter. When activated,
> that solenoid closes its internal, very large, contacts between the battery
> cable and the starter's field and armature windings. When you measure the
> voltage at the starter's battery terminal, you're measuring before those
> contacts and excluding all sources of voltage drop except the intervening
> cable, connections, and the battery itself. So, there's no obvious way for
> the starter switch to cause low voltage at the starter.
>
> HTH,
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
> www.gmcwipersetc.com

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
It helps also to know the test instrument. Most digital meters have screaming high input impedance, and will often measure a few volts on an open
wire
And let me note, if you bought one of the digital meters and the cables seem intermittent, do this. Take an x-acto
or box knife and shorten the plastic insulator around the banana plug just a but - an eighth or so. On some, including mine, the socket inside is
installed a bit too low for the plug to make good contact before the insulator hits the circuit board. Mine became reliably with this mod. eight bux
well spent.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Last edited by a moderator:
I want to thank everyone for all the input. The funny feel from the ignition switch is from a drag or resistance in the steering column. I was
measuring the voltage input to the solenoid (the reason for my reference to primary wire). The particular flow chart ended the same place with or
without the results I got. I was going to retest the voltage input to the solenoid however we have that southern California storm here for a few days
and I don't work well in the cold. I have multiple meters some cheap and some expensive. I have two in my work truck one that just stays in the GMC
and one in my daily driver. They are a necessary part of my work life. I am just making lists (and checking them twice) of things that will need to
be addressed and trying to prioritize them.

Once again thank you all for the responses. The knowledge here is amazing and the interest in helping is very encouraging.

THANKS AGAIN to everyone for the help

Melbo
--
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
 
OK. If I understand you correctly you are reading one of the small terminals of the solenoid. Because you have a 1973 coach both of the small
terminals are used. One is the lead that energizes the solenoid coil. The other is a lead that shorts out or bypasses the ignition resistor on the
points (non-HEI) ignition system while cranking.

Are you reading the correct solenoid terminal?

On the correct terminal you should normally read 0 volts and somewhere around 7 to 12 volts only when the starter is engaged.

On the wrong terminal you should read around 7 or 8 volts (Ignition voltage after the resistor) with the key on and 12 volts or a little less when
cranking.

You still have not stated if the solenoid clicks when you turn the ignition switch to the start position. If it clicks, do the headlights dim when
the key is turned to start.

Final comment. All of the above circuits have nothing to do with supplying of power to the starter. Starter motor power is supplied by the big #2 or
so cable. The solenoid switches the #2 cable power off and on to the starter motor.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
One thing stands out above. You note that the cable running to the rear batteries might not be robust enough to crank a 455. That cable isn't in the
455 starting circuit unless A) you have the house batteries in the rear; and B) the battery boost switch is enabled. The single front battery is the
chassis battery and in my humble opinion should never be used for anything else. The only commonality it has should be the isolater which provides it
with charging current.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Ken

Thanks for the clarification on what the two "primary" wires to the solenoid do. In my first post I noted that when the key was turned NADA NOTHING
-- I could have had BRICK instead of a starter. In a later post I noted that I bench tested the starter and had the same result nothing. That is the
reason the starter is at the rebuilders. I did not see that there were two primary wires running to the starter. I am used to having one primary wire
and the battery cable. I mentioned that I would like to do some more testing on the start circuits but I believe that I was on the terminal that you
refer to as the wrong terminal. That terminal showed 6.2 volts. The cables showed pretty much what the batter tested at varying less than a 10th of
a volt. When I got the 6.2 volt reading I was expecting a reading around the same as the battery minus a 10th or two. When I got the 6.2 reading I
looked at the print out that I had (page 388) from the 73-74 maintenance manual and a 7 volt reading in a flow chart caught my eye. I was unaware of
the second primary wire attached on the block side of the starter. When I saw the small wire I connected my test lead and got up inside and tried the
starter and got my 6.2 volts. I hope this kind of clears things up. When this cold front is gone I will do some more testing and when I get the
starter back I will have it to play with as well. Thanks again for the information about the purpose of the second wire.

Johnny

I was thinking of putting all of the batteries in the back. Not a definitive plan yet just a random thought. The fact that a lawn mower battery will
start the onan makes it much less necessary to have a large battery bank in the rear BUT if I did and used it to start the onan and supply house 12
volt and 120 inverter power it would need to be connected to the front battery. Yes isolating the start battery from the house system is the only way
to go. I had an incident where the house and start system were combined only while driving and my charging system went down. I was unaware that it
had happened and pulled into a campground connected to the pedestal and went on about my business. The next morning the start batts were low. Even
when I got everything running I had to run the generator with battery chargers plugged in to keep things charged enough to keep the systems running.
We were dry camping for a couple of days and could not shut the genny down while parked or driving. Everything worked out OK but keeping the systems
separate but able to be connected when necessary seems to be a good plan. That was the reason I mentioned that the "00" cables might not be robust
enough to start the 455. If it was necessary to use the rear battery as support it would involve moving a battery a long set of jumper cables or a
preplanned set up that would connect batteries in the back to the battery in the front. I like that last idea the best but if I do that I want to be
sure it will work as planned if and when it becomes necessary. Just my thoughts. Glad to hear that you are back on the road with your coach. I am
looking forward having a day like that sometime.

Thanks for the help

Melbo
--
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
 
yeh you'd need a large cable. Which begs the question, what benefit do you see from having the chassis battery in the rear?

--johnny

--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Now I can understand where the 6 volt figure came from. From the ignition coil through the ignition resistor.

From about 1956 on until the middle 70's most, if not all, GM 12 volt ignition systems were basically the same as the previous years 6 volt ignition
systems. The problem was that feeding the system with 12 volts caused too much current draw across the points and caused them to burn prematurely.

So solution was to insert a resistor in series with the primary of the coil and the points. This resistor dropped the voltage and the current flow
across the points to a respectable level. Sometimes these resistors were a porcelain block with a curled resistance wire in it. Sometimes they just
use a long resistance wire with insulation on it which is what GMC used. The result of all of this is the coil would then see around 6 to 8 volts
rather than the 12 to 14 that would be there without it.

After all of that, some engineer realized that during cranking the battery voltage dropped due to the high load at the battery caused by the starter.
So if they were to eliminate the resistor during cranking they would have a higher voltage at the plugs for starting. This is exactly what they
accomplished with the extra 18 ga. yellow wire going from the solenoid to the ignition coil. That solenoid terminal supplies +12 volts to the
ignition coil only when cranking meaning when the solenoid is energized.

SO if you were to read the voltage at the solenoid terminal it should be identical to what you would see at the + side of the ignition coil.
(something less than 12 volts due to starter load but higher than 6 or 7 with the resistor in the circuit.

I suggest, at this point, that you need to concentrate on why the solenoid is not being energized. Ignition switch, neutral safety switch, bad
solenoid coilm Bendix gear jammed / stuck are a few of the possibilities. Get out you voltmeter and start chasing down that circuit.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
This has gotten so confused, it's time for one on one. I nominate Ken Burton to continue with suggestions.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Johnny,

"If nominated, I will not accept. If elected, I will not serve." Lyndon B. Johnson

Here is where I think we are on this. I believe he was metering the wrong terminal on the start solenoid and maybe under the wrong conditions.

As I stated before, 6 or 7 volts on any of the three connections on the starter solenoid is a bad reading. Except on a points ignition engine when
the key is in run and metering the solenoid terminal that goes to the ignition coil. That is what I think he was metering.

He also states that the solenoid does not click or make any noise. So that is the symptom that he needs to chase and fix first and ignore the starter
motor for now which probably is good.

If the solenoid does not click then he needs to determine if the problem is mechanical or electrical. Usually it is electrical. So I am trying to
get him to put it in failure mode (key held in start mode) and take some readings to determine of there is a voltage loss at the solenoid and where
that loss is happening.


--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Sounds like his neutral safety switch is out of sync with his key. But
then, he is an expert troubleshooter and has already ruled that out. His
starter is at the rebuilder, currently, so he cannot comply with OUR
suggestions and report back. Oh well, Happy New Year everyone. Bob, if it
were me, I would probably torque those 7/16" nc bolts to 25 - 30 ft.lbs.
and blue loctite and forgetaboutit.
Jim Hupy
Salem, Oregon

On Tue, Dec 31, 2019, 4:59 PM Ken Burton via Gmclist <

> Johnny,
>
> "If nominated, I will not accept. If elected, I will not serve."
> Lyndon B. Johnson
>
>
> Here is where I think we are on this. I believe he was metering the wrong
> terminal on the start solenoid and maybe under the wrong conditions.
>
> As I stated before, 6 or 7 volts on any of the three connections on the
> starter solenoid is a bad reading. Except on a points ignition engine when
> the key is in run and metering the solenoid terminal that goes to the
> ignition coil. That is what I think he was metering.
>
> He also states that the solenoid does not click or make any noise. So
> that is the symptom that he needs to chase and fix first and ignore the
> starter
> motor for now which probably is good.
>
> If the solenoid does not click then he needs to determine if the problem
> is mechanical or electrical. Usually it is electrical. So I am trying to
> get him to put it in failure mode (key held in start mode) and take some
> readings to determine of there is a voltage loss at the solenoid and where
> that loss is happening.
>
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I am guessing the same thing but I want him to prove it. It also could be something stupid like a very weak battery that goes to a very low voltage
under load or the ignition switch. He as had a ton of guesses by himself and from others. So I am asking that he put it in failure mode (key turned
to start) and read the voltage at the solenoid. If bad, then the voltage at the battery. If good, then the voltage at the NSS and ign switch. It
also could be that the switch is simply out of adjustment on the column.

Let him prove which item is the culprit with a meter and then fix that item only.


On the bolt torque, I agree with your 25 to 30. I set it at 25 two days ago when we installed the trans. I think I will leave it there.

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Hey All

Got the starter and alternator back today. The starter took a bunch of parts including armature and fields. I got it installed and before I got the
wiring done had to go install a water heater for a customer. It was too cold for much work today so I will update as I have time and learn something
new.

Melbo
--
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
 
I have the same problem here. I have my trans and final drive about 80% installed and it is too cold to finish it for at least a few days. I still
need to install the starter, final drive, and axles. I also still need to fill the fluids and grease the bearings. It gets dark here between 4:30
and 5:00 which means it gets much colder then.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
I leave the final drive and axles in the coach and remove the transmission kid of around them. Mostly cos the FD is heavy and I'm paranoid about the
inner flange axle bolts having found them loose once.
New armature and field coils? Geez. Never seen both fail in one unit - actually never seen a field failure in a starter - but as Matt says, they
will keep going when they shouldn't. Makes me thing it lost a bearing and the armature chewed into the field. Anyhow, now he knows the starter
works:)

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Final drive is out because I needed to work on it and left the axle inner CV joint was also repacked. The stuff that was in it was like KARO syrup.

One of my helpers broke my starter solenoid while installing it. The end plastic was broken.

I called our the local rebuilder and he said to come by after 10 PM when he was working on year end taxes, or to stop in on Jan 2. I stopped by very
late and he gave me what I needed.

Because of this posting I asked him how often he had to replace a field or armature on one of these. He said it is very rare unless it had been in a
fire. He said fields maybe 1 in 200 and armatures around 1 in 100.

He said 99% of GM starters are clean up, turn the armature, replace bushings, drive, brushes, and solenoid. Painting is optional. $65.00 without
paint. He stocks the armature but not the field.

He has been doing this for 38 years.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
My guy's been doing them 50+ years. The last rebuild cost $31 w/tax &
paint (3+ yr ago). :-)
KenH.

On Wed, Jan 1, 2020, 7:08 PM Ken Burton via Gmclist
wrote:

> Final drive is out because I needed to work on it and left the axle inner
> CV joint was also repacked. The stuff that was in it was like KARO syrup.
>
>
> One of my helpers broke my starter solenoid while installing it. The end
> plastic was broken.
>
> I called our the local rebuilder and he said to come by after 10 PM when
> he was working on year end taxes, or to stop in on Jan 2. I stopped by
> very
> late and he gave me what I needed.
>
> Because of this posting I asked him how often he had to replace a field or
> armature on one of these. He said it is very rare unless it had been in a
> fire. He said fields maybe 1 in 200 and armatures around 1 in 100.
>
> He said 99% of GM starters are clean up, turn the armature, replace
> bushings, drive, brushes, and solenoid. Painting is optional. $65.00
> without
> paint. He stocks the armature but not the field.
>
> He has been doing this for 38 years.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I've had troubles with "hot soak" starts. After a hot run in hot weather, and stopping for fuel, the restart has always been a grinder. Tried
everything from parts house rebuilds to our local starter/motor rebuilder with no success. Even went as far as building a sheet metal shield between
the exhaust manifold and the starter. It helped but didn't cure the issue. I finally bit the bullet and got a "high Torque" starter off of eBay..
Starter with a high RPM, physically smaller starter with gear reduction. Have had no hot start issues. JWID
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
Try rebuilding your Carburetor. Might put a lower temp thermostat, too. You
are having heat soak, but it won't effect a starter in good shape with
adequate cables. It does boil the fuel and flood the engine.
Jim Hupy
Salem, Oregon

On Thu, Jan 2, 2020, 5:00 PM Larry via Gmclist
wrote:

> I've had troubles with "hot soak" starts. After a hot run in hot weather,
> and stopping for fuel, the restart has always been a grinder. Tried
> everything from parts house rebuilds to our local starter/motor rebuilder
> with no success. Even went as far as building a sheet metal shield between
> the exhaust manifold and the starter. It helped but didn't cure the issue.
> I finally bit the bullet and got a "high Torque" starter off of eBay..
> Starter with a high RPM, physically smaller starter with gear reduction.
> Have had no hot start issues. JWID
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
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