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Home » Public Forums » GMCnet » [GMCnet] Reviving the Cad 500  () 1 Vote
Re: [GMCnet] Reviving the Cad 500 [message #163108 is a reply to message #163015] Thu, 15 March 2012 21:15 Go to previous messageGo to previous message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma:
Senior Member
Hooray!!! I passed start-'er-up today, finally!

I was delayed until almost 3 PM by 95 yo problems. Then the 75 yo
problems began. I bought a new ignition module to satisfy yesterday's
diagnosis. After installing it, the spark indicator was a little more
reliable and the timing strobe USUALLY flashed -- but no life to the
engine a'tall. So, once more I went through all the setup stuff:
Find #1 TDC, set crank with the timing indicator at exactly the
desired BTDC, rotate the distributor to set the reluctor & pickup
points together. With that all set up -- AGAIN -- I did something I
should have done a long time ago: Fabricated a simple stiff wire
pointer to mount under a convenient bolt with the free end adjacent to
a scribe mark on the distributor body. Now, if I tinker with the
setting, I can easily get back to an exactly known setting.

With the air cleaner cover off, try starting again -- STILL no workee
-- even with the strobe flashing, showing the planned 10* BTDC, and
both injectors squirting nice cones.

About then, Stick showed up, so he can testify to my frustration and
the gymnastics I went through: Finally resorting to reading the
manual, I started through the EFI troubleshooting charts and wiring
diagrams -- not necessarily in any logical order. First steps of the
troubleshooting procedure: 1. Ignition on. 2. Is SES light
illuminated NOPE! So, I spent 30-45 minutes trying to figure out why
the LED Service Engine Soon warning indicator on my custom dash was no
longer working. I STILL don't know, but I finally got around to
connecting a test lamp in place of it and getting that to shine.

After lots of other tests, including Ohming-out every ground
connection, I decided the wiring was still OK and that there were no
disconnected leads like those that delayed my first re-start. So I
sat and thought about the rules: With fuel, compression (which I had
redundantly checked), and spark, all now obviously at the correct
times, it's GOT to run! But it doesn't. What have I NOT replaced?
How 'bout the coil? It's putting out, I KNOW that (I even got bitten
once yesterday), but it's not NEW.

Stick had to go to the spelling bee then, so I lost my moral support.
That didn't stop me from tearing down the HEI distributor cap to
remove the coil -- a first for me! Can you believe that after all
these years, that's true??? I didn't know that the coil cover, held
on with two (sometimes 3) self-tapping screws conceals the coil and
the 5 terminals inside that little overhang on the side. The coil is
held into the cap with another 4 self-tapping screws through the iron
core, one of those also retains a wire lead from the coil winding.
Still another presses the core down against a convoluted metal strip
which makes up the center terminal of the 3-contact inner connector.
The outer two of those terminals are the BATT and TACH terminals, and
extend to those outer two locations where the single connectors
attach. Those terminals just seat in spaces in the distributor cap
and are retained by the coil cover.

Guess what -- that center terminal under the coil core was as rusted
as if it had been laying out in the yard for 36 years, instead of
hidden under there!

When I tore down my nearly-new Cad non-computer controlled distributor
cap, I found a nice shiny new coil with 3 shiny terminals, so I popped
them into the cap still on the engine.

Hit the starter ... Varooom! It runs!!! Hallelujah!!!

And even after I shut it down, it did it again. And again,..And Again!

If I had just Ohm'd out the assembled distributor cap/coil
combination, I'd probably have found the bad connection in the coil
primary caused by that rusty strip. :-(

I finally let it run long enough to get hot, then shut it down and
drained the oil. With a jug of oil sitting at the driver's seat (so I
can't forget there's none in the engine), I left it to drain for the
night and came in to brag to HER about how I got IT running -- after
only 3 wasted days of dumb "troubleshooting". :-)

We'll make it to Shawnee yet! That's a challenge, JimK.

Ken H.


On Wed, Mar 14, 2012 at 10:29 PM, Ken Henderson wrote:
> Well, I flunked crank-er'-up still again.
>...
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
 
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