65 K1000 305E Starter 'clunk'

[squighound]

Hey guys,

I have a 1965 GMC K1000 4x4 with the 305E V6, and a 4spd manual transmission. The starter was shot so I replaced it (with a new WAI 4038N). The new starter makes a "clunk" when trying to start maybe 1 out of 4 times (not consistent). The other 3 times it starts just fine. In troubleshooting so far, I've done the following:
- bench-tested the starter (fires 10/10 times no issues)
- tested continuity for all the wires from the ignition switch to the starter (all good)
- replaced the starter switch with a new one
- sanded the blade connections on the female side (plastic block) where the starter switch plugs in to the wiring harness

Any ideas? When it makes the "clunk", it sounds like the bendex is hitting something and not extending all the way to engage the flywheel. Does it maybe need shims? There weren't any on the old starter.

Thanks in advance!

[AZKen]

Nose not engaged properly into hole. Pilot diameter has burr or casting blemish. Teeth on starter not properly chamfered for lead in. Bad/weak solenoid. Good on bench bad under slam load.
Hydraulic lock beginning on motor. check oil for milk. Wrong gear installed by starter maker.

[kknotts]

Worn or Warped flywheel?

[Jim A]

You have probably tried it. but it would be easy to try the starter at as many positions as you can. Marks or eyeball on damper could guide.
This would point to kknotts' idea.

[squighound]

Thanks, guys. Did a visual inspection of the flywheel and the starter - no issues. All teeth are present and in perfect condition on the flywheel - no warping. All teeth on the starter bendex are good, edges are chamfered as expected. No odd wear marks, etc. I'm stumped. Here's a video of it making the sound. If anyone has an idea please let me know. Thanks!

https://youtu.be/VRf6RJPdt6o

[AZKen]

Definitely an electrical problem. Please tell me that it also does that with the dash mounted starter switch and not just the remote switch. Paranoia says bad remote switch. If it does it with both, it's a sticky solenoid/bad solenoid. Wiring/cabling/ground thing.

NEXT is something you REALLY REALLY have to be thorough with so we can move on without missing it.
1. Triple check your battery at a reliable shop. The starter draws +/- 400 amps. Battery will show good charge but break down under load. Never trust a battery.
2. NO PAINT OR GREASE on starter mounting surface.
3. NO PAINT OR GREASE on bell housing mating surface.
4. Battery ground goes on starter mounting bolt. Clean bolt surfaces there.
5. Both ends of battery ground cable and it's clamps/ring terminal, tight, shinny clean, new good condition. CABLE: 2 ga min.
6. Both ends of battery positive cable and it's clamps/ring terminal, tight, shinny clean, new good condition. CABLE: 2 ga Min.
7. Battery posts, clean shinny, tight clamps.
8. Need ground straps from motor to frame, frame to body, NO PAINT.

You must not assume all is good, something is not good. So give these things we speak of a real test, not just a look.

If all that checks out, I say solenoid...or slap one on now. Maybe even a bad starter. We await your success. We will stay with you if you keep us updated.

[Jim A]

I'd try Ken's list one at a time or you will never know what the problem was.
Number one is being very sure of all four battery contacts.
It sounds like the solenoid is firmly engaging, but perhaps only occasionally making electrical contact with the starter windings.

[squighound]

Hey guys - quick update.

Yes, it does the same thing with the remote switch -AND- with the ignition switch. I have already tested continuity from the starter switch to each of the wires on the starter (and replaced the starter switch), but i tried the remote switch just to take the wiring out of the equation.

As for your other suggestions:

1. Tested the battery at home: voltage, CCA, starting system, charging system all "green", but I still need to take the battery to a shop to get tested. I also tried another battery I have on hand (used to bench-test the starter), but it has the same behaviour.

2. Done - was already bare metal, but I cleaned it with brake cleaner.

3. Done - had some paint, so I wire brushed it off, then cleaned with brake cleaner.

4. There's already a ground wire from the negative terminal to the intake manifold, a ground strap from the engine block to the frame, and another ground strap from the frame to the body. I added a ground cable (4ga - couldn't find a 2ga) directly from the negative terminal on the battery to the starter mounting bolt. Cleaned the bolt surface on both sides.

5. Cleaned both ends of the negative cable and made sure they were tight.

6. Cleaned both ends of the positive cable and made sure they were tight.

7. Cleaned up the battery posts and clamping surfaces and ensured they were tight.

With all that.... no change in behaviour. The starter is brand-new, but I thought maybe there was something wrong with it, so I grabbed ANOTHER new starter - same make/model (WAI Global 4038N). Even with the second new starter... no change.

I was stumped before, but now I'm really stumped. I'll get the battery tested at a shop, but other than that I don't know what else to try. If you have any more suggestions, I'm open to ideas. Thanks!

Originally Posted by AZKen

Definitely an electrical problem. Please tell me that it also does that with the dash mounted starter switch and not just the remote switch. Paranoia says bad remote switch. If it does it with both, it's a sticky solenoid/bad solenoid. Wiring/cabling/ground thing.

NEXT is something you REALLY REALLY have to be thorough with so we can move on without missing it.
1. Triple check your battery at a reliable shop. The starter draws +/- 400 amps. Battery will show good charge but break down under load. Never trust a battery.
2. NO PAINT OR GREASE on starter mounting surface.
3. NO PAINT OR GREASE on bell housing mating surface.
4. Battery ground goes on starter mounting bolt. Clean bolt surfaces there.
5. Both ends of battery ground cable and it's clamps/ring terminal, tight, shinny clean, new good condition. CABLE: 2 ga min.
6. Both ends of battery positive cable and it's clamps/ring terminal, tight, shinny clean, new good condition. CABLE: 2 ga Min.
7. Battery posts, clean shinny, tight clamps.
8. Need ground straps from motor to frame, frame to body, NO PAINT.

You must not assume all is good, something is not good. So give these things we speak of a real test, not just a look.

If all that checks out, I say solenoid...or slap one on now. Maybe even a bad starter. We await your success. We will stay with you if you keep us updated.

[AZKen]

So logic says it's NOT the battery and NOT the starter because you tried different one's. Logic says it's not switches or solenoid if each new starter had it's own solenoid.
Logic says it's not ground because you cleaned and checked and tightened.
Logic says 90% chance it's electrical, 10% it's mechanical. Starter pulls +/- 450 amps on battery!!!!!!

These are my logic. Logic has to be tested.

We are in a brainstorming mode now after all you have reported. I'm blasting out thoughts. Brainstorming is an actual engineering technique for meetings and large groups to solve an issue. It may trigger the guys and gals here on 6066club to offer a new idea or test for you. Or see a missed point.

Not wiring because you bypassed with remote starter switch.
Remember I said check oil for milky. Don't want it to be hydraulic lock. I busted three starter noses before I caught on to that once.

Take ALL plugs out and take off dizzy tower wire and crank to see if you can get it to clunk once. Watch for something shooting out plug holes.

Other than that, could be
1. a bad spot on flywheel teeth.
2. You missed something.
3. Two bad batteries.
4. two bad starters.
5. battery cable broken inside the insulation or at clamp and can't see it.
6. Clutch sticking. Whatever that means.
7. Piston sticking, rotating component sticking like bearings
8. Oil or water in cylinder
9. Sticking valve causing compression/back pressure
10. Timing off causing compression/back pressure
11. Those internal compression/check valves in head are stuck
12. Fan belts too tight. Naw, can't be that.



This last batch of things are sketchy ideas I know but it's pointing to something very odd happening.
It does crank good and start good with no starter or grinding noise. Fires 10 x 10 on the bench. Do that plugs-out test and report. Gotta get some change to happen to get a clue.
Intermittent stuff is a pain. You may have to run it til it fixes itself or breaks more.
I have a headache now.

You haven't done anything to anything you forgot to say have you?

[Jim A]

OK, time's up.
What did you find as the cause?