Starter not disengaging

[NorCalC20LWB]

Rebuilt my 350 w/HEI and am now working the bugs out, first time experience for me so there are a few. The starter began to stay engaged even with the key out, so I replaced the ignition switch first, no difference. Figured it must be something in the starter/solenoid then so took the opportunity to upgrade to a mini starter, should be here today or tomorrow. After taking the solenoid apart it appears the contact points have been arcing together. I did screw up when replacing the headers and forgot to take off the battery negative cable and got some decent sparks when the wrench touched the positive lead on the solenoid and the engine block. Would this have caused the problem? Want to make sure I don't run into the same issue after replacing the starter.

As always, thanks for any help!

Brian

[truckster]

There are two possibilities: It could be that the starter was still energized, or it could be that the Bendix (starter throw-out) was not returning. If the starter was still energized, it's likely a wiring mistake. The arcing on your solenoid doesn't look serious enough to keep it engaged. If the rest of the starter was as clean as the solenoid, that makes it less likely that the Bendix was sticking.

I would double-check your wiring before you hook up the new starter. If it was a problem with the starter itself your new starter should fix it.

[NorCalC20LWB]

Thanks Truckster, I will double check the wiring first, but I thought it looked pretty good when I replaced the ignition switch. Good observation on the solenoid looking clean, forgot to mention I replaced it during the rebuild because I cracked the plastic from tightening the pos cable connection too tight. Unforced error on my part...I did not replace the starter though, it looks original to me, but who knows.

[special-K]

Is it an automatic? Could it be the neutral safety switch gone bad shorting?

[truckster]

Originally Posted by special-K

Is it an automatic? Could it be the neutral safety switch gone bad shorting?

If the neutral safety switch shorted it would just allow the starter to be energized while it's in gear. Unless the key is turned there shouldn't be any electricity flowing through the NSS.

Knowing it's an old starter, I'd bench test it off the vehicle with jumper cables. See if the Bendix stays in the outboard position when the power is cut.

[NorCalC20LWB]

It is an automatic, TH350, and I did replace the neutral safety switch a year or so ago (reverse lights wouldn't go on). Bench testing the starter sounds like a good idea, I assume that would mean touching the negative jumper cable to the metal housing and the positive jumper cable to the post the purple wire attaches to?

[truckster]

Originally Posted by NorCalC20LWB

It is an automatic, TH350, and I did replace the neutral safety switch a year or so ago (reverse lights wouldn't go on). Bench testing the starter sounds like a good idea, I assume that would mean touching the negative jumper cable to the metal housing and the positive jumper cable to the post the purple wire attaches to?

Here's how I do it: I find a sturdy place where the starter's not going to move a whole lot - if you've got a bench vise it will fit in that's a good idea, because there's a lot of torque when you put the power to it. I carefully connect the black jumper to the housing (or the vise if that's what I'm using) and the red jumper to the main post on the solenoid (this is the one you want to be really careful with, so it doesn't slip off the post). Then I connect red to + and black to - on the battery. I use an old screwdriver to jumper from the hot post on the starter to the S terminal on the solenoid. The Bendix (the gear drive) should snap to the outboard position when the starter is engaged and snap back in as soon as the power is removed from the S terminal.

[NorCalC20LWB]

Thanks Truckster for the "how to" bench testing procedure. Just did it and the starter seems to work fine, not sure that's good news at this point since the problem must be elsewhere. The new mini starter should be here tomorrow, I guess at this point just keep fingers crossed and hope it doesn't stick.

[firedemon]

I have had a starter that got stuck in the out position because it needed a shim
I don't remember why

[truckster]

Originally Posted by firedemon

I have had a starter that got stuck in the out position because it needed a shim
I don't remember why

If it needed a shim it was a clearance problem with the flywheel/flexplate. Not very common, but I've heard of it happening.

Often when the starters get old and dirty the shaft just needs to be cleaned and lubricated to make the Bendix slide more easily.

[NorCalC20LWB]

I thought of shims also, but it did not have any before the rebuild, plus did not sound like it was binding/too tight. On a side note, I had an Acura MDX that didn't release from the flywheel when the engine started making a kind of screeching noise for a second. The fix was to grease the starter gear, is that something that should be done on these starters also to help engaging/disengaging from the flywheel?

[NorCalC20LWB]

Update:

New mini starter is in and so far works perfectly. I think the problem was one of three things:

First, even though the old starter performed well during a bench test, maybe the gear stuck just enough when installed to prevent disengaging.

Second, the instructions very specifically stated the mating surface with the block needed to be clean and paint free, my block was painted on this surface from the rebuild. Sanded all the orange paint off so there is metal to metal to contact with the starter.

Third, and least likely I think, I have a really annoying oil leak at the rear of the engine and the starter area was dripping with oil. Not sure if this could cause a problem, but it is cleaned up now.

So far so good, thanks again for all the help and suggestions!