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Starter fails to turn over intermittently

I have a '93 nissan pathfinder with a starter problem: frequently when I turn the key nothing happens.
My mechanic has replaced the starter twice, replaced the battery, the battery cables and most recently replaced the starter relay, all to no effect. They also tested the alternator, after replacing the battery didn’t solve the problem, but the battery is getting a charge.

2 symptoms:
first, it starts consistently when the engine is cold, fails frequently when the engine is hot.
2nd, when it fails I bump the engine once or twice and then the starter system works.
By bump the engine I mean:
I have a stick shift, I shift into first gear, step out of the car, press the clutch down with my right foot, push the car forward getting up to perhaps 1 mph, take my foot off the clutch to transfer the energy to the engine in a ‘bump’.
For some reason, through all of the attempts to fix the problem, this has always worked to get the starter to turn over. My mechanic doesn’t know what to make of this, but it keeps me from getting stuck and requiring a tow. However this is inconvenient and I expect that one day this will stop working, so I would like to get my vehicle back to working order. I haven’t gone camping this year because I am afraid of getting stuck miles from anywhere help is available.

If anyone has a idea of the problem please let me know. Alternately, if there are any components in the starter circuit I haven’t yet replaced let me know what they are. I am ready to try anything.

Thanks for any help. -Fred

Sounds like you have a couple of bad teeth on the flywheel. If a couple of teeth are bad it will prevent the starter from engaging…and thus starting.

It’s rare this happens on any make…Have your mechanic remove the starter and look inside with a flashlight to inspect the teeth while someone turns the engine over.

It could also be bad teeth on the starter…but you said that was replaced…so I’d be surprised if that’s the case.

If it is the flywheel…unfortunately the only fix is to replace it…and that means a clutch job which is expensive.

Could be the flywheel, but OP says ‘nothing happens’ - fredrated, do you mean absolutely nothing? No noise, no click, no whirrrr? If absolutely nothing happens, then it’s not the flywheel. It might be some connection or switch, like the clutch safety switch or the ignition switch.

You might try temporarily wiring up an indicator light that glows when the starter’s getting 12v, see if it glows when ‘nothing’ happens.

I think the problem is with the clutch safety switch. This switch is on the clutch pedal assembly under the dash, and will not send the voltage to the starter without the clutch pedal depressed. Check that the switch is adjusted properly and any pads or mounting plates are not damaged. I’ve seen some models where the pads are plastic or some type of rubber that gets brittle, cracks, and falls out. This leaves a hole that the plunger to the switch squeezes through and never gets compressed.

No noise, no click, no whirrrr?

If it’s the flywheel…you won’t get a whirrr…Should get a click…though…

Why I think it’s the flywheel…is because he moves the truck a little and then it starts…Maybe just coincidence but that should not happen if it’s an electrical problem.

I agree, the ‘move the truck and it works’ would be consistent with a chipped flywheel/weak solenoid, but the starter should still be spinning, right?

but the starter should still be spinning, right?

Not necessarily…Some starters won’t start spinning until they are fully engaged. Remember a starter gear is retracted when it’s NOT trying to turn the engine over.

True - if he hooks up an indicator light it’ll show whether it’s getting 12V or not, would answer the ‘is it a switch’ question.

Good point…When it’s failing…check to see if voltage is getting to the starter. If no voltage…then it’s electrical.

Isn’t diagnosing a car problem over the internet fun???

Since this car has a manual transmission maybe there’s a problem with a clutch safety switch if this particular model is equipped with one. A switch like this prevents starter motor operation while the vehicle is in any forward or reverse gear.

Next time it acts up try hooking your foot under the clutch pedal and lifting the pedal towards you. If it starts then you know the switch is probably out of adjustment.

I simply cannot remember if this model had a clutch switch or not. What happens with switches like this is that many of them have a rubber pad on them that depresses the button on the switch. While new the rubber is soft and returns to form. With age the button makes an indentation in the rubber pad and this indentation remains even when the button is not making contact. This little dent is enough to cause the circuit through the switch to remain open.

Just something for consideration anyway.

This vehicle has a clutch safety switch…

Still don’t understand HOW it’s an electrical problem when you push it forward for a few feet the starter then engages.

Pushing it a few feet has nothing to do with it starting. Working the clutch pedal a couple of times does. I agree its the switch or the OP is not pushing the clutch pedal down far enough the first time.

I have a 97 Nissan PU, it shares a lot of stuff with the Pathfinders of those years. I’m finding more frequently that this is happening to me also, but I just push a little harder on the clutch pedal and it starts, every time.

The description of how to get it to work is consistent with a damaged flywheel. If that is what it is, you should hear a click and whirr sound when the key is turned, both of which will be much quieter than the engine cranking over. If you turn the key and hear dead silence, it’s time to look elsewhere and “bumping” the truck and getting it to start is coincidental. If a bad flywheel is to blame, the starter will still operate, same as it would when bench testing it. It just cannot engage the flywheel or turn the engine, but it will run.

I think it the safety switch. Try pumping the clutch pedal a few times. Make sure you push it as far as it will go down. I will bet it will start.