New battery
New alternator
New Starter (twice)

Have problem where starter periodically won't start and just gives you the one loud click. (Usually this is the starter or a connection to it).

Cleaned all connections but do have an issue with the tiny nut that connects to starter (for ignition to solenoid) not being able to crank down real tight

Here's the other odd part, me lightly tapping on starter USUALLY gets it to start, but not always. It tends to do it after a longer drive and not when "cold" (hasn't been driven in 8+ hours).

Further information......this all started after having transmission rebuilt........and to be honest the guy seemed incompetent but didn't know until after he had to do the job multiple times to get it right. (Starting to think he never did). Is it possibly flywheel related?

 

 

My guess is starter #3 is needed, that solenoid post has to be secure, if it starts by tapping on the starter. The issue is probably in the starter or the loose solenoid wire.

 

New OEM starter, or some junkey rebuilt starters you are putting in?
You have gone thru at least 2 starters, so that is suspect.

 

Both starters were new, not rebuilt and both were Genuine GM starters. Literally as good as it gets for replacements. Again, all this started after having transmission rebuilt. And they work intermittently. Seems like after a long drive is the most common time it acts up. And at first, everytime I hit the starter it would work, but then after many times of that over many months, there was times hitting it wouldn't work. Or wouldn't work until I waited few hours and then tried again hitting it.

That's my whole point and frustration......nothing adds up perfectly. It's all over the place.

I have now cleaned the ground under the passenger door area, resecured the small wire going to starter (solenoid specifically) so it's much tighter by adding a second nut to that stud, even cleaned the ground contacts on firewall (but it didn't even need it). I also switched the relays for starter and Day Lamps since identical and side by side, just to see if that could make a difference.

So far today we drove it 100 miles with several stops, no issues but that means nothing. After adding the second new GM starter, it made it over a month with never doing it once, then few days ago it did it again out of the blue. (Basically proving it was never the starter in the first place). But why hitting it then gets it to work 4 out of 5 times seems very odd to me. (Unless I'm giggling that connection for solenoid when key is turned, by hitting starter).

Heat / long drives seems to affect it
Hitting it usually gets it to start but not always

 

Watched video but it wasn't the same issue as our Hummer. In video there was no click at all, not just the 1 loud click. Plus ours is intermittent/random and not all the time. It would take me testing just the right thing, AS IT ACTS UP, for me to have a chance of even figuring something out with a test light. Haven't been that fortunate yet. Greatly appreciate you responding/trying though.

 

Was able to get the small wire to solenoid tighter by adding a second nut to the stud. I also cleaned the ground under the passenger door area. Also swapped the relay for starter with relay for Day Lamps as they are side by side and identical number relays. So far today we drove over 100 miles with several stops and no issues, but that doesn't sadly mean anything. After putting the second new starter on, it didn't do it for over a month. So only time will tell. Will deffinently keep post updated and greatly appreciate any input even if it doesn't help.

 

sometimes there are shim plates used on the starter mating surface to space the starter pinion from binding.

 

THanks for the reply. I'm no professional by any means, but I thought that's more for "cheaper" aftermarket starters you need to shim and even further they would come with shims if it was one of those. (Or it was true for older v8's like muscle cars).

I used genuine GM starters (brand new not rebuilt)

Did you (or anyone here for that matter) even need to use shims when replacing their starter on their H2?

 

So you used Genuine GM starters. That is good. But are they brand new? GM also sells rebuilt parts.

If brand new, not rebuilt, then it kind of eliminates the starter itself, unless you got a couple of bad starters in a row (unlikely).

But.....heat-soak is a common problem with many electrical and mechanical devices. I have see the starter start to work after being tapped with a hammer for over 50 years. Or after cooling down. Because I would think more power draw is required if the starter is hot, just like with any other electrical devices where heat increases resistance.

Alternatively, think tolerances. Something binds as it heats up and tolerances shrink. Could that be a starter or a flywheel issue? We do not know. Since it only started when the transmission was rebuilt, I can see how you would suspect a mating problem between flywheel and starter. But unlikely the issue.

I presume you also replaced the solenoids when you replaced the starters? All in one unit, siting on the starter or inside it? I have not looked the Hummer starter, so not sure how it is configured. Tapping the solenoid to engage it would suggest a bad solenoid. Tapping it usually breaks a stuck contact pole and makes it work.

That would suggest the starters are all defective. But since you did the trany thing, it rather suggests that they somehow bent or mangled the flywheel, but that could just be a red herring.
Here is the thing. If a good starter was trying to mate to a bad flywheel gear, it would cause monster noise. And you are not hearing any. Ditto if the starter or flywheel was mounted incorrectly, so that is likely not it.

So where does this leave us? Not many options left for a non-active starter. Guessing bad starter, bad power feed (not enough amps getting to starter when hot), or bad ground.
Cheapest route is to FIRST a) test the battery properly with a load-drop test, and then if OK, b) change out the main cable form battery to starter.

The biggest clue here is the word "HOT".

Hope this info helps.