Technical Ducato starting problem - not the usual

[Blueywr1]

I've been lurking for the last 18 months, but this is my first post, so before you delve in, I'll say, "Hi".

Vehicle: 2006 / FIAT Ducato 2.8JTD X244 / manual (A Class motorhome)

Problem: Intermittent starting failure

• Most of the time the vehicle starts as normal, however, sometimes it does not
• A single click can be heard from the engine bay (sounds like it’s from the starter motor)
• Immobiliser light on the instrument panel goes out – as normal
• Can happen with either key
• When it does not start, selecting 4th gear and pushing the vehicle until resistance is felt, has then enabled it to start – this may be a wild coincidence I know

Action taken:

• New vehicle battery fitted
• Starter motor replaced twice (incorrectly thinking this was the problem)
• Earth straps tested on a handheld machine at the garage
• OBD scan shows no fault code
• Battery clamps replaced
• OEM immobiliser disconnected
• Aftermarket immobiliser disconnected
• Trawled many websites / forums, but unable to find same problem

It had an MOT yesterday – passed with no advisories – then failed to start on their ramp! Selected 4th gear, mechanic pushed it a few cm and it started immediately. It’s a twin-axle and weighs 4500kg, so it’s not something we want to be attempting to push often. It’s booked to return to the garage for further investigation work, but I thought I’d ask the community for any pointers that I can pass on to the garage. The garage is not FIAT specific, but they do have a contract with a large motorhome seller for maintenance / MOT work.
Appreciate your time. Thanks.

 

[Googlebot]

I would replace the earth straps, the test won’t replicate starter current trying to pass through them and it’s cheap and easy.

Alternatively use a jump lead to create a temporary one and see if that works.

Sounds like an electrical problem to me and the bumping of the engine is sorting it.

 

[Communicator]

I would replace the earth straps, the test won’t replicate starter current trying to pass through them and it’s cheap and easy.

Alternatively use a jump lead to create a temporary one and see if that works.

Sounds like an electrical problem to me and the bumping of the engine is sorting it.

I am sorry, but the x244 does not have earth straps. My PVC is an x244 2,8jtd. On the x244 the battery negative cable descends to a flag terminal below the front end of the battery forward of the RHS engine mounting, (chassis earth point). The same cable continues under the intercooler and radiator to terminate on an extended starter motor stud at the clutch housing. No specific earth strap. Corrosion can occur inside the flag terminal at the chassis earth point, but it is rare.

I do agree with the electrical diagnosis, as it sounds as though the starter solenoid is not receiving sufficient power to drive the pinon into engagement, and close the starter motor contact.

Possible causes include poor supply or bad connection at ignition switch, faulty ignition switch, faulty interconnection at engine bay fusebox. and damaged solenoid cable at starter motor. and as suggested a faulty earth cable.

An alternative purely mechanical possibility is a damaged ring gear tooth on the flywheel, blocking the starter pinion engagement,

 

[Blueywr1]

I would replace the earth straps, the test won’t replicate starter current trying to pass through them and it’s cheap and easy.

Alternatively use a jump lead to create a temporary one and see if that works.

Sounds like an electrical problem to me and the bumping of the engine is sorting it.

Thanks for the reply. Apologies, I did not state that I've tried the jump lead to the chassis earth bolt. It made no difference.
I have contemplated replacing the earth cables, but because the jump lead bypass didn't work, I keep shying away from it.

 

[Blueywr1]

I am sorry, but the x244 does not have earth straps. My PVC is an x244 2,8jtd. On the x244 the battery negative cable descends to a flag terminal below the front end of the battery forward of the RHS engine mounting, (chassis earth point). The same cable continues under the intercooler and radiator to terminate on an extended starter motor stud at the clutch housing. No specific earth strap. Corrosion can occur inside the flag terminal at the chassis earth point, but it is rare.

I do agree with the electrical diagnosis, as it sounds as though the starter solenoid is not receiving sufficient power to drive the pinon into engagement, and close the starter motor contact.

Possible causes include poor supply or bad connection at ignition switch, faulty ignition switch, faulty interconnection at engine bay fusebox. and damaged solenoid cable at starter motor. and as suggested a faulty earth cable.

An alternative purely mechanical possibility is a damaged ring gear tooth on the flywheel, blocking the starter pinion engagement,

Thanks for the reply. The garage have actually suggested inspecting the flywheel for tooth damage, but said gearbox will need to be removed. Sounded expensive, which is fine if it fixes it.
Appreciate your other suggestions.
We keep throwing cash at it, in the hope that one of these fixes will resolve the issue and make it reliable and the fun vehicle we want it to be.
The pot of money is depleting!

 

[Googlebot]

Thanks for the reply. Apologies, I did not state that I've tried the jump lead to the chassis earth bolt. It made no difference.
I have contemplated replacing the earth cables, but because the jump lead bypass didn't work, I keep shying away from it.

Did you try directly to the engine rather than the chassis?

 

[Communicator]

Thanks for the reply. The garage have actually suggested inspecting the flywheel for tooth damage, but said gearbox will need to be removed. Sounded expensive, which is fine if it fixes it.
Appreciate your other suggestions.
We keep throwing cash at it, in the hope that one of these fixes will resolve the issue and make it reliable and the fun vehicle we want it to be.
The pot of money is depleting!

I was thinking of removing starter, and inspecting flywheel via opening. Engine can be turned via suitable socket on crankshaft pulley bolt. Taking box out. is time consuming, and hence expensive. I wonder whether @bugsymike has any thoughts on this? If my thinking is correct, then engine will stop in any of four positions, corresponding to compression strokes. if damage is only at one position, then only 25% chance of failure. rocking engine past this point would allow starter to engage.

 

[jackwhoo]

Thanks for the reply. Apologies, I did not state that I've tried the jump lead to the chassis earth bolt. It made no difference.
I have contemplated replacing the earth cables, but because the jump lead bypass didn't work, I keep shying away from it.

In this case jump lead from battery negative to clean metal on engine/gearbox

 

[jackwhoo]

I was thinking of removing starter, and inspecting flywheel via opening. Engine can be turned via suitable socket on crankshaft pulley bolt. Taking box out. is time consuming, and hence expensive. I wonder whether @bugsymike has any thoughts on this? If my thinking is correct, then engine will stop in any of four positions, corresponding to compression strokes. if damage is only at one position, then only 25% chance of failure. rocking engine past this point would allow starter to engage.

Crank turned slowly will enable all of starter ring gear to be examined , slow turning enables any compression to leak past piston / rings

Though if ring gear damaged I would expect to hear starter just spinning rather than a click

 

[jackwhoo]

Possible damaged main positive cable from battery to starter

 

[Anthony489]

Hi

You have received useful advice above, but it might help you to know more about starter motors which for the last few decades have all been of the pre-engaged type.

On one side of the starter body is a cylindrical solenoid (= electromagnet ). When you turn the key to the start position, a fairly heavy current (e.g. 30 Amps) flows from the ignition switch through the solenoid winding via the thinner of the two cables. The resulting magnetic field attracts an internal piece which has two jobs. One job is to move the pinion into engagement with the ring gear. The other job is to close the main contacts, allowing a very heavy current (e.g. 500 Amps) to flow directly from the battery via the thicker cable. This very heavy current flows through the motor and makes it turn. If for some reason the pinion doesn't move far enough to fully engage, all you hear is a click from the solenoid but the main contacts won't touch and the motor therefore won't turn.

Reasons for failure to fully engage are usually low battery and/or excessive resistance in the solenoid circuit, resulting in reduced solenoid current and a feeble pull-in. A garage should be able to easily measure the solenoid current with a clamp-on DC ammeter.

Less commonly, even with normal solenoid current any unusual mechanical resistance to the pinion movement could prevent its full engagement. Hence the advice above to check the state of the pinion and ring gear teeth. From memory, 4 cylinder engines tend to come to rest in one of two positions 180 degrees apart, so the ring gear wear (if any) will be in two places and nudging the crankshaft round a little will give a less worn section. Having said this, one of the reasons for pre-engaged starters is to prevent this sort of wear, so maybe there has been a historic alignment problem.

 

[bugsymike]

I was thinking of removing starter, and inspecting flywheel via opening. Engine can be turned via suitable socket on crankshaft pulley bolt. Taking box out. is time consuming, and hence expensive. I wonder whether @bugsymike has any thoughts on this? If my thinking is correct, then engine will stop in any of four positions, corresponding to compression strokes. if damage is only at one position, then only 25% chance of failure. rocking engine past this point would allow starter to engage.

Generally they stop in one of two positions, as in two pistons up and two down.
So to prove if starter ring gear worn in either of those positions you may need only move the crank a small amount to check.
Way back in the old days it was not unheard of for someone to remove the ring gear and move it to a different spot
I have fitted many new ring gears in the past , however it was in the days of inertia starters rather than the modern pre engaged design which generally doesn't cause that wear, as it engages and then turns, rather than spining and "smashing" it's way in to engagement.
I see from OPs original comments it was mentioned putting vehicle into 4th gear and slightly moving had the affect of permitting engine to start, so although unusual it may be possible ring gear is damaged in one spot.
The only time I have seen that was where a S/H engine that had been standing in a yard rusting and was fitted without care re ring gear.

 

[Blueywr1]

Did you try directly to the engine rather than the chassis?

no, i used the bolt as described / shown by @Communicator, where the existing earth cable goes to first.

 

[Communicator]

no, i used the bolt as described / shown by @Communicator, where the existing earth cable goes to first.

The chassis earth point is not directly in the starter motor circuit. Jump lead should be directly between battery negative and engine,

 

[Blueywr1]

The chassis earth point is not directly in the starter motor circuit. Jump lead should be directly between battery negative and engine,

ok, i will try this when it happens again.
anywhere on the engine block? with it being an a-class, access as you will guys will probably know, is very awkward!

 

[Communicator]

ok, i will try this when it happens again.
anywhere on the engine block? with it being an a-class, access as you will guys will probably know, is very awkward!

Engine lifting lug is usually clean, and accessible.

 

[jackwhoo]

Clean unpainted metal, make sure to have a good electrical contact

 

[Blueywr1]

storm bertie is allowing me to to spend part of my day scrolling through this informative forum, reading the many threads about ducato's not starting. your names appear often!
it may be of no relevance, but i have something to add to my scenario; i have a noco booster pack and i have been able to try it at times when the vehicle has refused to start. most times it has made no impact, but on the odd occasion, it seems to have had. this might also deserve the, "wild coincidence" tag?

 

[Googlebot]

Where do you put the boost pack to?

If it’s a decent earth point on the engine and it starts, that might help identify a wiring issue with the earth.

 

[Blueywr1]

Where do you put the boost pack to?

If it’s a decent earth point on the engine and it starts, that might help identify a wiring issue with the earth.

i have only ever put the clips on to the battery terminals, but, also worth noting, the noco is not a big one for a moho, ie. a large diesel engine, so perhaps if the vehicle battery was a little low on juice, the noco may not have enough umph to fire it up?