OM642 'lazy starter motor'??

[BTB 500]

I have a strange problem with the OM642 V6 CDI in our Vito, which is occasionally reluctant to start when hot. It turns over very slowly, just as if the battery was flat. But once cooled down it turns over at a more normal speed and starts fine. It only does it now and again, but today I was stuck somewhere for 30 minutes and about to call the AA out when it finally started! I drove home again (same 16 mile route), left it 5 minutes, and it restarted without any problem. It definitely seems to be heat-related in some way as cold starts are always fine ... this can only apply to something in the engine bay as the battery is under the passenger seat.

The garage took the battery out and tested it at the last service, checked the terminals and earth strap, and couldn't find any problem. One possibility they mentioned was a 'lazy starter motor'. I'd not heard of this before, but from a quick Google it does seem to be a 'thing'. They said they replaced quite a few on BMWs in particular, but were reluctant to change mine as they couldn't guarantee it would be an improvement.

After today's incident I'm inclined to replace the battery anyway as it is 16 years old now and has covered 160k miles. This can't hurt and might improve things. My only other thought was that the engine could perhaps be low on compression when cold (making it easier for a slightly weak battery to turn over), but most of the time it does restart fine when hot. Of course an engine is normally harder to turn over when cold.

Any other thoughts?

TIA

 

[clk320x]

Camshaft Position Sensor?

 

[HB]

Funny you mention this Bill. The starter on our V6 350 sounded lazy till I replaced the original 10 year old battery. It was absolutely perfect after this.
Hopefully this is all your Vito needs.

 

[W1ghty]

Glow plug relay module , cps (as above) ?

 

[Will]

Could it be a cabling issue to the starter motor itself (corrosion/poor connection/damaged wires) - when hot the increased resistance would give similar symptoms to a low battery (voltage drop)

 

[BTB 500]

Could it be a cabling issue to the starter motor itself (corrosion/poor connection/damaged wires) - when hot the increased resistance would give similar symptoms to a low battery (voltage drop)

That's possible ... the garage did have a look but not sure how much they could see/get to. We use the van a fair bit though and it does a hot re-start every time I go to get fuel (6 miles away) without ever having had a problem. And today it was OK after driving home again

It would be easier if I could reproduce it at home as I could then potentially check voltage / current etc. to get a better idea what's going on.

 

[BTB 500]

Camshaft Position Sensor?

Would that cause very slow cranking? Today it was so bad to start with that the engine actually stopped turning over.

 

[BTB 500]

Glow plug relay module , cps (as above) ?

The relay was replaced last year, but it started fine for a good few months before having a new one fitted (just took a little longer when cold).

 

[BTB 500]

Funny you mention this Bill. The starter on our V6 350 sounded lazy till I replaced the original 10 year old battery. It was absolutely perfect after this.
Hopefully this is all your Vito needs.

I'm hoping it will help but I don't think the battery on its own would explain the issue. We'd not used the van for a couple of days, it started fine from cold, drove 16 miles, turned it off for 5 mins and it would then barely even turn over. Multiple attempts to start it over a 30 minute period slowly saw the cranking speed increase to the point where it was enough for the engine to fire. Then after driving the 16 miles home again I was able to stop & restart it fine.

 

[grober]

Pre-engaged Starter Motor (Automobile)

https://lh6.ggpht.com/_Ii1ukGkfijY/SqnvwKgIreI/AAAAAAAACkk/xU_zzCeX9ho/clip_image002_thumb.jpg?imgmax=800

MY GUESS is that heat soak is causing the pre-engage mechanism to seize preventing the solenoid from making good main contacts to the motor itself or the contacts themselves could be needing cleaned up. this might be aleviated by lubricating the mechanism IF THE STARTER IS EASY TO GET OFF!

 

[HB]

I'm hoping it will help but I don't think the battery on its own would explain the issue. We'd not used the van for a couple of days, it started fine from cold, drove 16 miles, turned it off for 5 mins and it would then barely even turn over. Multiple attempts to start it over a 30 minute period slowly saw the cranking speed increase to the point where it was enough for the engine to fire. Then after driving the 16 miles home again I was able to stop & restart it fine.

Hmm. Over to the experts.

 

[BTB 500]

Pre-engaged Starter Motor (Automobile)

https://lh6.ggpht.com/_Ii1ukGkfijY/SqnvwKgIreI/AAAAAAAACkk/xU_zzCeX9ho/clip_image002_thumb.jpg?imgmax=800

MY GUESS is that heat soak is causing the pre-engage mechanism to seize preventing the solenoid from making good main contacts to the motor itself or the contacts themselves could be needing cleaned up. this might be aleviated by lubricating the mechanism IF THE STARTER IS EASY TO GET OFF!

I wonder if this is behind the 'lazy starter motor' thing?

Made me think of my old Fiat 126, which had a starter lever connected to a steel cable running back to the engine. Pulling this slid the starter motor up against the power supply terminals and into engagement with the flywheel. Then a spring pushed it back when you let go of the lever - top technology

 

[m80]

It's all remote guessing,
but I would be looking to eliminate the starter solenoid.

Problem there is you would ideally need to short the heavy duty terminals when the problem is apparent.
The starter relay seems ok or the starter wouldn't attempt anything.

If you continue to turn the ignition for a start, on off, on, off, and eventually the starter were to engage and spin, that might well indicate the the solenoid is the issue, with an eventual good connection at the solenoid.

If your battery is failing to give the balls for a start the voltage would reduce massively during an attempt.
If the starter isn't trying due to faulty solenoid then the voltage will be less affected (there would still be a voltage reduction due to other introduced loads).

 

[BTB 500]

It's all remote guessing,
but I would be looking to eliminate the starter solenoid.

Problem there is you would ideally need to short the heavy duty terminals when the problem is apparent.
The starter relay seems ok or the starter wouldn't attempt anything.

If you continue to turn the ignition for a start, on off, on, off, and eventually the starter were to engage and spin, that might well indicate the the solenoid is the issue, with an eventual good connection at the solenoid.

If your battery is failing to give the balls for a start the voltage would reduce massively during an attempt.
If the starter isn't trying due to faulty solenoid then the voltage will be less affected (there would still be a voltage reduction due to other introduced loads).

The starter engages normally every time you turn the key ... it's just that the engine turns over *really* slowly, to the point of stopping after a few revolutions initially. I must have tried 6 or 7 times over the course of 30 minutes (I had the bonnet open the whole time to help it cool off) and it slowly got better (faster) each time. After driving home again I did a hot restart without any problem.

 

[WilliamParsons]

The issue with your OM642 V6 CDI engine in your Vito, where it's reluctant to start when hot but starts fine when cold, could be related to a heat-sensitive component like the starter motor or the engine's temperature sensors. When hot, certain parts may experience increased resistance or reduced efficiency, causing slow cranking. It's advisable to have a mechanic diagnose and inspect the starter motor, temperature sensors, and associated wiring to pinpoint and address the heat-related starting problem.

 

[OneForTheRoad]

Would that cause very slow cranking? Today it was so bad to start with that the engine actually stopped turning over.

Id favour the crankshaft sensor over the cam shaft sensor . Both would show fault with icarsoft scanner . Pitted and scored starter contact plates can cause issues,but usually it's simply, will turn over or not turn over .

 

[BTB 500]

Id favour the crankshaft sensor over the cam shaft sensor . Both would show fault with icarsoft scanner . Pitted and scored starter contact plates can cause issues,but usually it's simply, will turn over or not turn over .

I had a crankshaft position sensor problem on it before ... it turned over normally on the starter but wouldn't fire (at all).

 

[BTB 500]

The issue with your OM642 V6 CDI engine in your Vito, where it's reluctant to start when hot but starts fine when cold, could be related to a heat-sensitive component like the starter motor or the engine's temperature sensors. When hot, certain parts may experience increased resistance or reduced efficiency, causing slow cranking. It's advisable to have a mechanic diagnose and inspect the starter motor, temperature sensors, and associated wiring to pinpoint and address the heat-related starting problem.

Problem is that it's intermittent ... hot starts are OK most of the time. They did check it over earlier in the year but couldn't find a problem.

After 16 years it could do with a new battery anyway so I'll replace that for now and see if it helps at all. I tried a cold start with a spare battery connected to the terminals under the bonnet and it definitely spun over faster.

 

[Londonscottish]

I had a new new starter fitted to mine over the summer. It had started to turn over more slowly than normal - I actually thought the battery was on the way out until the starter failed completely and blew a fuse.

The new starter spins way faster.