98 K1500 motor swap but no start

AMEN to that!!

Follow Up Question to your thoughts about marrying the old starter to a new flywheel. When connecting the flywheel of the newly installed motor to the torque converter of the original transmission, do you need to be mindful of which holes of each line up with each other? If so, I did not do that. I just lined up the 3 bolt holes on the flywheel randomly to 3 thread holes on the torque converter and tightened it down... did I miss something in that step and might that be part of the problem? I can move the flywheel with the help of screwdriver when the starter is uninstalled, so it still spins freely with hand power...

DHud said:

do you need to be mindful of which holes of each line up with each other? If so, I did not do that. I just lined up the 3 bolt holes on the flywheel randomly to 3 thread holes on the torque converter and tightened it down.

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"Shouldn't" make any difference.

Best-practice is to keep the flexplate and the converter aligned as from the factory...but in real life it doesn't matter. And it's impossible to keep factory alignment when you change the flywheel, or change the converter.

So again, it doesn't matter.

DHud said:

I had a little time to work on the truck during the little guys’ nap time!

Update:
Pulled the starter and did a bench test myself - got it to engage with no problems using jumper cables and a battery. (Bummer - I was hoping this would be the obvious problem) Reinstalled the starter and tried jumping over the switch in the same way that I bench tested it. (I know, a little redneck, but I’m getting slightly impatient). Jumping it with a screwdriver while the ignition is in the off position (and again with key in run position) resulted in same “Ping - dead” effect. I had my son quickly disconnect and reconnect the battery after everything went dead and that brought the power back on right away. While I was laying under the truck with my redneck screwdriver, I noticed that it sure seemed like the “Ping” sound was coming from the starter.
Can a starter engage with no load and falter like this when put under load? Will a parts store do more extensive testing on a starter to reveal something deeper? I still need to take the battery in to get it load tested…
The saga continues! Thanks guys!

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starters can absolutely poop the bed under load. At the shop we used to test them with a piece of two by four on the bench.

Unfortunately I'm not going to be able to give an update until next week bcs we're heading out of town for a wedding/mini-vaca tomorrow.... I was hoping to tinker with the truck before we left but another car in the family fleet needed emergency attention!

Battery passed the Load Test - so that eliminates the battery as the problem. I'll continue the investigation upon returning next week! Thanks for your input everyone!

DHud said:

Unfortunately I'm not going to be able to give an update until next week bcs we're heading out of town for a wedding/mini-vaca tomorrow.... I was hoping to tinker with the truck before we left but another car in the family fleet needed emergency attention!

Battery passed the Load Test - so that eliminates the battery as the problem. I'll continue the investigation upon returning next week! Thanks for your input everyone!

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Understand completely. Live in the moment, and enjoy the time with your family.
We'll pick this up where we left off when you return, and together push this thing
over the finish line.

Safe travels --

Hey all! Back from our weekend away and had a chance to do some tinkering on the truck last night:

UPDATE:
- Good news: I was able to get the starter to engage while installed in the truck by jumping it straight from the battery with Jumper Cables
- I then started narrowing down the possible "trouble areas" and long-story-short, it appears that my Negative Battery Terminal Bolt is the culprit. I have cleaned and inspected that thing at least 2 times in this whole process, but I am able to get the starter to engage while installed by turning the ignition key IF I have the Positive line from the battery installed onto the starter as it should be and a jumper cable going from a bare terminal bolt installed into the Negative threads of the battery and connected to the bare end of the negative line that is normally screwed onto the Negative Terminal Bolt - essentially eliminating the Negative Terminal Bolt ONLY. Doing this allows me to crank the motor at will using the key and ignition without losing power...
- Next step, once I get home from work later, is to install new terminal bolt and plug everything back in and see if it will fire.
- Anything I might be missing before trying to fire it up?

Thanks everyone! Your help has been invaluable!

UPDATE:
Good News Guys - She's Running!

And, as most of you have already experienced in your years of wrenching, it was a stupid little thing. The Battery's Negative Terminal Bolt. As you can see in the attached picture, I heeded @Schurkey in post #9 way back when and cleaned the snot out of all terminal connections and grounds.... This baby was spit-shined - but for some reason, it was not making a solid connection to the battery. The only way I figured it out was to follow the sage wisdom of @Road Trip to continue narrowing down the problem. Once I isolated the system and essentially bypassed only the Negative Terminal Bolt, I knew that had to be the problem. I installed a new one, plugged everything back in and she fired up first turn! Can't believe it - $8 and weeks of time!

Now, I just need to figure out why it's not shifting right... but that's for another thread...

Thank you for all of your awesome help! This forum has to be the BEST I've found!

DHud said:

UPDATE:
Good News Guys - She's Running!

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Excellent! Sincere thanks for staying with this and working it logically all the way through
to the successful conclusion. And by sharing what finally fixed your electrical anomaly, this
changes the thread from just FSM-based theory into a real-world troubleshooting process
and a specific fix that others can learn from.

DHud said:

And, as most of you have already experienced in your years of wrenching, it was a stupid little thing. The Battery's Negative Terminal Bolt.

...Once I isolated the system and essentially bypassed only the Negative Terminal Bolt, I knew that had to be the problem.
I installed a new one, plugged everything back in and she fired up first turn! Can't believe it - $8 and weeks of time!

Click to expand...

I was happy to read your synopsis above, for this was my stated goal back towards the beginning:

Road Trip said:

But my goal for sharing all this is for you to be able to troubleshoot to the root cause in as few moves as possible. And more importantly,
once you fix this you will understand exactly why it failed in the first place.

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At about the halfway point, we had so many questions that it was near impossible to
come up with a good theory as to why. When there are too many unknowns/variables,
this is when we go from a big picture/top down troubleshooting approach, to a bottom up
Building Block strategy:

Road Trip said:

No doubt you are aware that we are dealing with something out of the ordinary. Doesn't mean that it can't be fixed,
but it does mean that we are going to have to assume everything is bad, and go through the effort of proving to
ourselves that each piece of the powerplant puzzle is good.

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Which you did. Without firing the parts cannon. (aka: Ready, Fire, Aim. :0)

DHud said:

There are probably some who are reading this exchange who are thinking, just replace all the stuff with new and move on. I’m getting there myself, but I really want to know the specific reason this isn’t working so I’m better equipped in the future.

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Congratulations on achieving your goal. I'm sure that you feel a lot more comfortable now
with the GMT400 electrical subsystem than you did prior to starting this engine swap. And
I also hope that your son enjoyed learning how Analytic Troubleshooting / Symptom Directed
Diagnosis is used to tighten up the problem description and help develop a structured testing
approach.

DHud said:

Thank you for all of your awesome help! This forum has to be the BEST I've found!

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There are a *lot* of good, sharp, helpful folks in here. It's one thing to drive something
old solo. Quite another to drive old with all the documented info and years of experience
here in the GMT400 forum to tap into if necessary. A lot less stress & way more fun to boot,
especially given the feel/vibe of those who choose to be a part of the old truck community.

Now that you've regained control over the electrical system, best of luck with the remaining
loose ends of getting your truck back to work & earning it's keep.

Safe travels --

DHud said:

And, as most of you have already experienced in your years of wrenching, it was a stupid little thing. The Battery's Negative Terminal Bolt. As you can see in the attached picture, I heeded @Schurkey in post #9 way back when and cleaned the snot out of all terminal connections and grounds.... This baby was spit-shined - but for some reason, it was not making a solid connection to the battery.

Click to expand...

I was pondering this, and wanted to see if anyone else has suffered a similar misfortune & figured
out the root cause.

It turns out that over in the Corvette forum a guy at one time was suffering similar 'starter click,
then dead' symptoms. What he troubleshot it down to was a length incompatibility between the
battery bolt and the battery connection. Seems that his bolt was a reported .020" too long, causing
the bolt to tighten up because it bottomed out before the electrical cable connection was completely
tight to the battery. And the tightness of the bolt could easily give the mechanic a false sense of how
tight the cable is clamped to the battery. (!)

In his case, it would work for awhile, fail, he would retighten it, and it would be gtg for another month
or so. It's a good read, especially after what you've been through. (tight bolt, yet loose cable)

****

Don't know if your battery cable bolt was originally made for a different cable and now too long with
a different cable? Or possibly was the threaded battery hole manufactured just slightly out of spec
(too shallow) and this was what caused the bolt to bottom out/tighten up before cinching the electrical
cable securely to the battery?

From personal experience I don't use the fastener tightness to judge if a battery cable is secure.
(either style connector) I always attempt to twist the cable side-to-side in order to judge a secure,
tight cable connection.

****

Given how clean you got that battery bolt there was no way that normal debris/corrosion got in
the way of current flow. I can see how a tolerance stack up between bolt, cable, and battery hole
depth could cause what you were experiencing. Wild stuff.

I've pulled the threads on a side post battery and ended up with an intermittent connection issue. I have to assume the little 8mm hex oem design was done specifically to help minimize that possibility. But I, of course, hated that little hex head and put in a bolt/nuts system and then promptly overtightened one of them. It was easy to isolate though as symptoms appeared immediately after my super duper "upgrade"