Faulty starter

[mauricio_28]

After several instances of failed starts with no cranking over at all, the dealer has acknowledged a problem with the starter motor. A replacement will be installed this weekend. Nevertheless, a doubt remains. Whenever the rig doesn't start, I crawl underneath, whack the starter a couple of times with a wrench, and that does it; upon turning the key it starts once again. What exactly is going on inside the starter?

 

[HenryJ]

Sounds like either the drive is sticking or perhaps the solenoid. The "banging" on it frees the stuck drive.

 

[dust devil]

I would agree that it is probably a stuck bendix. Most such sticking is attributable to 1) lack of adequate lubrication on the starter shaft, i.e., dry parts; 2) corrosion or debris interfering with the bendix, frequently in the form of junk stuck to the starter shaft. Replacement only gets you a clean starter. The old one was probably still functional, just in need of cleaning and a light lube. Best way to tell is to remove the defective starter, take it a part, and look.

 

[mauricio_28]

It's been taken apart, cleaned and lubed twice. The problem comes back after a while.

 

[dust devil]

Without bench testing it, it would be hard to guess what is going on. If the assembly is clean and not binding due to dry parts or fine grit but still does not respond, there is perhaps an electrical fault. I wouldn't expect such a fault to be cured by banging on the unit though.

Heat can also play a part in starter failure. If it fails when really hot, but works when cool, try to isolate the starter from the heat source, with a blanket or shield. Next time you take it apart, look at the tolerances between moving parts in the engagement device. If there are close tolerances between relatively heavy metal parts, you could be getting binding when parts grow due to heat, which might be mitigated by adding clearance where needed. This is hard to guess at without one in front of me, but take a look.

For reference, is this starter the one on your Nissan? If so, do you have the 4.0?

 

[mauricio_28]

Yes, it's the starter on my D40 TDI Navara...