Free spinning starter motor (no start, no click)

boone

Member
Hi All,

Just back from an Easter trip with the 4x4 316 NCV truck. Really impressed with the driveability, not so much with fuel economy (14.5-15L/100), but that happens with a big wooden box on the back at 100km/hour I guess.

On the way back I went to start the truck. A short wheezy crank or few (no start) then I slipped off the key. I went to start again and the starter motor appeared to be no longer engaging. Nothing else wrong, just the starter spins (clearly heard) without engaging anything. I ended up getting a pull start (super easy, started like a dream) and drove home (no stopping...).

Just wondering if there are any insights on this particular problem? In particular - is it likely that I have broken all my ring gear teeth and need to replace that? Or is it likely to be an electrical gremlin along the lines of Eric's 'click, no-start' thread? It does seem to be a different set of issues to that common thread though - there is no click and the starter runs freely.

Overview:
  • Starting has been unconvincing at best since I got the truck mid last year despite replacing the starter motor and installing a new battery.
  • Otherwise the truck drives very well (I don't really think fuel consumption is too bad given the 2m box on the back of the tray).
  • Car almost started when I slipped off the key but was very wheezy - seems to take quite a bit longer than it should and seems to be making some wheezy/slipping noises
  • Since then the starter has just spun completely freely. No warning lights or other issues have come up.
  • Car is running perfectly from what I can tell.
Would the best option be to replace the 'y-harness' and see if that fixes it? Or is there a simple method to check if I've stuffed my ring gear?

Any hints greatly appreciated.
I'm in Adelaide BTW.

Cheers,
Daniel
 

autostaretx

Erratic Member
A spinning starter motor with no engagement with the flywheel teeth is a failure of the Bendix mechanism at the end of the starter motor's shaft.
((the starter solenoid mechanically pushes the gear into engagement (and then a spring dis-engages the starter's pinion gear when the starter is turned off)

The "fix"? A new starter, which also replaces the solenoid. (the linkage from the solenoid to the "push-the-gear" could have broken)

There is the small chance of ring gear damage, but inspection through the inspection ports (or the removed starter's hole) should confirm that.
If it was *individual* missing teeth, the chances of them ending up at the starter (again) on the next attempt after driving would be highly unlikely.


--------------quoth service manual-----------
The energized solenoid pull-in coil pulls in the solenoid plunger. The solenoid plunger pulls the shift
lever in the starter motor. This engages the starter overrunning clutch and pinion gear with the starter ring
gear on the manual transmission flywheel or on the automatic transmission torque converter or torque
converter drive plate.
As the solenoid plunger reaches the end of its travel, the solenoid contact disc completes the high amperage
starter feed circuit and energizes the solenoid plunger hold-in coil. Current now flows between
the solenoid battery terminal and the starter motor, energizing the starter.
Once the engine starts, the overrunning clutch protects the starter motor from damage by allowing the
starter pinion gear to spin faster than the pinion shaft. When the driver releases the ignition switch to the
On position, the starter relay coil is de-energized. This causes the relay contacts to open. When the relay
contacts open, the starter solenoid plunger hold-in coil is de-energized.
-----------------------------------

--dick
 
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boone

Member
Thanks Dick,
That's kind of what I was thinking (hoping?) would be the issue. Severely disappointing to be broken after pretty well less than 5000km (but perhaps 6 months).

Does anyone have a suggestion where I should buy a replacement? I'm not going to fork out $800 for someone else to do it shoddily again...
 

boone

Member
I think it should have been new... It looks new. Repco appear to have a unit that fits for $240 so i might try that. Will try to pull out and inspect and maybe bench test the old one first though...
 

Eric Experience

Well-known member
boone.
You are about to pay the price of buying non genuine parts. It always works out better to use genuine parts. Eric.
 

Sockeye770

Active member
From my experience with replacement parts for my Valiants, cheap repo parts made with chinasium, don't last as long as a good used genuine part.
 

boone

Member
Thanks @Eric Experience and @Sockeye770. Insights heeded... If i need to replace, do you have a suggested source for a starter maybe? I'm a bit under the pump for work for the next 7 days but can then take a day off to get the starter out...
 

Eric Experience

Well-known member
Boone,
Never use a hammer on a sprinter starter, they are ceramic not steel so can be broken, Only use genuine parts as mentioned above, If you had used genuine when you first changed it you would not have this problem. Cheaper in the long run. Eric.
 

CraftD

New member
I had the same problem...was intermittent but gradually got more frequent to the point where i was lucky if it started at all... New original starter motor put in by the local shop and all fixed... Was the weirdest noise...Wheezy is definitely a good word for it. I'm in wollongong so no good to you shop wise. Good luck!
 

autostaretx

Erratic Member
If you want to try it, it should be possible to disassemble the solenoid from the starter and puzzle out precisely what is broken.
In Ye Olden Days, it would sometimes be the pin that connects the solenoid's linear "actuator" (moving core) with the lever arm to the gear engagement fork. (think "cotter pin" or "roll pin" or "small bolt through a bearing")

But for a quick fix: new starter.

--dick
 

jaahn

Active member
Hi Daniel :)
My suggestion would be to order a genuine Bosch starter for your Sprinter. That is what the factory fitted. Most auto suppliers and professional auto electricians will be Bosh agents and wil supply one I feel sure. However impress that you want genuine Bosch brand not a copy.
That way you get the Bosch quality but no extra markup by Mercedes.
Good luck Jaahn
 

boone

Member
Thanks all for your replies, I'll get onto taking it out in the next few days or so. I'll definitely seek out a bosch myself this time... @CraftD, great to hear you had a similar problem and fixed it this way! looking forward to more convincing starts I hope...

This is the truck by the way :) Not my business - the guy didn't get rid of his decals, I'll get around to it eventually.
 

Attachments

boone

Member
Hi All,

So an update: I've gotten the starter out (what a Schlep!!). The stupid silver cover thing is the core problem.

Bench test indicates it is ok - I hooked up a link wire to the main positive terminal, grounded it and energised it, then touched the other end of the link wire to the solenoid terminal. The starter gear pops out and spins (though not super fast but that's probably to do with me using weak jumper cables...)

The ring gear also looks good (phew).

Does anyone have a suggestion as to what my issue could be? I'm lost...

The key is that the starter motor was just spinning freely when it was in-place. And it started more like a hrrr hrrr hrrr hrrrrrr chugga chug (chugga chug is the starting bit) rather than a nice turn over when it was starting.
 

autostaretx

Erratic Member
So it's possible it's bad wiring between the battery and the starter .... (what year is your Sprinter? Ahh... photo shows NCV3)
The NCV3 has the infamous "Y-cable" that has been a consistent source of trouble over the years (weak crimps, corroded strands breaking, etc etc).
There is also the engine grounding cable that connects the engine block (the starter's negative) to the Sprinter frame .... that can be loose or have corrosion and simply broken-due-to-vibration stranding. In the T1N it bridges the rubber engine mount that's under the fuel filter:

GroundStrap2005.jpg

... i don't know where it is in an NCV3.

Even a slightly-bad connection in the starter circuit can prevent the starter from getting anywhere near full power.
The contacts in the starter solenoid (and the short thick wire between the solenoid and the starter) can fail/corrode/develop resistance.
Just testing the starter "on the bench" without a load will NOT reveal such issues (although the "slow" extension of the gear is a tell-tale that it's NOT a happy camper ... that gear is supposed to *SNAP* out there to engage the teeth with spinning against the face of the flywheel.)

--dick
 

boone

Member
Thanks Dick (@autostaretx),
I'll have a look at the ground strap. I think the 2012 NCVs had the improved version of the y-cable but will check that. At the moment I am thinking of going back to square 1: reinstalling the starter and seeking to bridge the solenoid and main positive terminals to see if i can get the engine to crank.

It could be a relay on the solenoid side too i guess - does anyone know how to get at the relays on the LHS near the bonnet-release lever?

As I learn I am starting to understand more of the terminology on here (including Eric's write-up on click-no-start), and more of the Sprinter. I am also becoming more convinced that, other than a few gremlins, these are really good engines and great vehicles. Having had the T1N and the NCV now I am leaning toward the NCV as a more comfortable and overall better vehicle.

Thanks, always happy to receive other insights on this issue. And will update this as I slowly work through it.

Cheers,
daniel
 

autostaretx

Erratic Member
I don't have access to this particular reference (any more), but here's where they are:

BCMasSAM.png

and this 2007 service manual might have the procedure for extracting them:

http://www.diysprinter.co.uk/reference/2007-sprinter-service-information.pdf <-2007 MB service manual
http://www.diysprinter.co.uk/reference/2007-sprinter-wiring-information.pdf <- MB wiring diagram from above
http://www.diysprinter.co.uk/reference/2007_Wiring-sprinter-2500.pdf <-- 3rd party wiring diagrams


Your fuse allocation booklet may also describe the location of some of the relays.

--dick
 

boone

Member
Final update:

Starting issues are fixed with a replacement second-hand unit (genuine). The truck is starting better than it has yet (while in my ownership).

So, this issue was a little different to that outlined be Eric. The symptoms were weak starting, followed by no-starting combined with the starter motor spinning but not engaging the flywheel. It was fixed by replacing the starter motor with a genuine article.

So all comments on 'using genuine' appear to be genuine - use non-genuine parts at likely substantial risk. The solenoid on the crappy one seems smaller than that on the genuine one.

Also, it is a short job, but a bit of a pig of a job unless you have tiny hands.

Eric's thread was useful in helping me start to think about what the issue might be.

Thinking my next job will be to replace the fuel filter and air filter, then to chop the 'box' (motorhome) down to become a poptop to save on fuel and improve offroadability, then onto cleaning up the EGR.

Thanks all for your help!
 

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