Unique B4 Starting Issue (with Video)

Okay so in the last year or so I've been having trouble starting. It's been getting worse and especially with the onset of winter and cold temps here in Colorado. It just seems like the starter plunger doesn't engage some of the time. A new starter did not fix the issue!

Here is a video (turn sound on) so you can hear what it sounds like. In this case you'll hear it almost start the first time, then "miss" twice, and then start the fourth time. If it's really cold, it sometimes takes 10+ tries to get it to catch.

Now, before jumping to conclusions, note these things I have done:

1) Rotated the engine while looking through the flywheel inspection window. No damage or missing teeth that I saw.

2) Replaced the starter with a new Bosch reman. In this case it starts fine about half the time. The other half it sounds like the plunger gear hits the flywheel and doesn't engage. Turning the flywheel a couple of teeth through the inspection window let's it line up and it then it starts. Pretty annoying so I put the old one back in. Image of the new and old starters, and you can see the starter teeth are fine.

3) When the old starter was out, I disassembled the plunger solenoid and cleaned and lubed everything. Looked fine.

Any ideas?

So when it does this does the starter motor operate or does it just do nothing?

If the starter motor runs when you turn the key then the solenoid is doing its job, because the solenoid will only engage the motor drive when the solenoid plunger is at full extension, that's when the contact for power to the motor itself is made.

That's how the starter prevents the motor from running before engaging the flywheel. The contacts for power to the starter motor are only made once the solenoid extends the starter gear fully.

There's something else going on here that's causing an issue but I'm not sure what.

At first blush I suspected that maybe your ignition switch was going south but I'm not so sure, have you checked continuity or voltage on the solenoid trigger wire yet?

Steve

Seems like the bendix isn’t extending/engaging when the solenoid sends power. You had this starter rebuilt or is it a Bosch shelf stock starter?

-Todd

@Steve_Addy - the starter motor always spins/works, it just doesn't seem to spin the flywheel. I have not checked voltages/voltage drop. It could potentially be a bad ground. It's been cold and snowy here and I don't have an indoor garage so haven't poked at it recently, but it's starting to warm up.

@ToddA1 - the starter that's in there is the original as far as I know. As I mentioned, when I temporarily installed the new Bosch rebuild a few months ago, it would work some of the time, but some of the time it sounded like the solenoid would deploy but the starter gear would hit the flywheel and not engage the teeth so nothing would happen. I had to manually rotate the flywheel by a few teeth to get it to engage and spin.

Now that it's warming up I'm going to check and clean grounds, and then reinstall the new starter to see what happens.

I side with Todd on this one. That's the sound of the starter when it isn't engaging with the flywheel.

Digital Corpus said:

I side with Todd on this one. That's the sound of the starter when it isn't engaging with the flywheel.

Click to expand...

Ditto, sounds like the starter motor is getting power before the drive gear has engaged the flywheel.

This is not a good situation, as both the drive gear and flywheel (teeth) can be damaged when the starter works like this.

Steve

Steve Addy said:

Ditto, sounds like the starter motor is getting power before the drive gear has engaged the flywheel.
This is not a good situation, as both the drive gear and flywheel (teeth) can be damaged when the starter works like this.
Steve

Click to expand...

In his previous thread he mentioned that the ring gear on the flywheel might be missing teeth.

OP, you chan check this visually a few different ways to confirm/deny that specific diagnosys:
Raise car onto jack stands
Remove rubber stopper on top of transmission
Engage transmission into 1st gear
Spin a front wheel by hand and observe one full rev. of the flywheel

Or you can remove the lower cover and watch the flywheel that way, but it may be harder to see the teeth.