An Earthy Subject

Willum

Active Member
It may be that I was the only one in the world who didn't know about this - but I doubt it. All the same, forgive me if this an egg-sucking exercise...........
For those of us who have a Sevel-built X250 base unit (Citroen/Peugeot/Fiat) from the last 10 years or so:
There is a problem with the earth strap from the engine to the chassis that can cause a whole raft of weird faults and having a computer, or several, at the heart of the system, all kinds of faults appear and disappear in random fashion.
Lots of faults can appear on the dash readouts, or just one. My (Fiat) showed its hand by, for absolutely no explicable reason, increasing the idle RPM from the normal 850-ish, up to 1400. That was in a motorway service station - quite a long way from our destination. It otherwise ran and drove fine and, happily, got there without incident.
It didn't do it again but I promised myself I would inspect the wiring harness in the engine bay for abrasion damage - another common fault that should be looked for, even if no problems are seen (prevention is MUCH better than cure in this instance)
Next time I tried to start it, it was just a tiny bit sluggish. I was curious but it started fine and that was that.
The next time it was more sluggish on the starter and the glowplug light flashed for a long while after it started. The idle then did the same trick and increased to about 1400 RPM.
The next time (five minutes later) I started it - it didn't. Just a click and a dash full of lights.
The battery 'at rest' voltage checked out OK but not brilliant, 12.9, rather than the usual 13.2.
I won't bore you with the rest of the tale of trying to find out what was wrong. Most of it was me sweating on it not being a computer/wiring meltdown. The remaining effort was expended on research.
Here's a link to a lengthy discussion I found about the problem. The guy who started - and solved - it is pretty clued up and generous with his time and advice.
http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/X250-Engine-earth-fault/21815/

The shortened version of the solution to the problem was:
1. Remove the left hand headlamp and the top of the air filter and check the wiring harness where it crosses the steel tube bracket for the computer mounting. Mine had the protective, corrugated, hard plastic, split conduit already fitted. If yours is OK and doesn't have any conduit, I strongly suggest you fit some. Fried computers are expensive to replace.
2. Next, fit a new, corrosion-protected earth strap. There are several suggestions as to where to fit them. I went from the well cleaned existing chassis mounting point to one of the bolts that holds the starter motor to the engine. It's the starter motor that takes the biggest current draw - by far - so the best point to connect it in my humble opinion. Cut out all the middle men.
The strap I fitted was a £5-odd Halfords battery negative lead, 24" long, and did the job nicely. Braided straps are fine, but tend to let the water and salt into the crimps more readily - most likely the root of the problem with the original strap.
Don't be tempted to use thin, cheap, nasty cable, with skinny terminals. Something with at least an 8mm conductor, ie, 8mm excluding any insulation sleeving, is what is required. Something as thick as the cable that connects your battery to the chassis is even better. It carries several hundred amps when you turn the key.
The INSTANT the strap was fitted, all the problems went away, the battery voltage went back up and after a switch-off and restart, all the 'alleged' engine/system faults reset themselves.

Knowing what I know now, I would suggest that one is fitted regardless of any problems manifesting themselves. It's a bit late when it makes like a Christmas tree and you break out in a sweat in the middle of nowhere.:think:

Just for interest's sake, the RPM increase is because the earth is so bad, the alternator voltage drops, the computer thinks it's too low because of load, so it increases the RPM to compensate.
Will
 

snail

Well-Known Member
Hi Will, this is a very common fault I thought most people new about it is brought up time after time on the mmm forum where I always look for technical help, Euroserve is very knowledgeable as he is a white van fleet operator running Fiat
and Mercs
Ours is earlier fiat based no problems yet after ten years x240 heavy chassis on 16 inch wheels
You should save that forum on your favourite as there are other specialist there as well
Snail
 

Willum

Active Member
Hi Will, this is a very common fault I thought most people new about it is brought up time after time on the mmm forum where I always look for technical help, Euroserve is very knowledgeable as he is a white van fleet operator running Fiat
and Mercs
Ours is earlier fiat based no problems yet after ten years x240 heavy chassis on 16 inch wheels
You should save that forum on your favourite as there are other specialist there as well
Snail
Silly thing is I've been a member of Out and About Live for many years - trouble is, I rarely went on there - to the extent that last time I tried, I had to re-register. Serves me right, I guess.
I knew about the computer wiring harness problem but always understood it was only the early X250s. Turns out my understanding was correct - but there's no telling, so I checked whilst I was in there, having had a sweaty moment in the early stages wondering if the wiring harness problem was actually not cured on mine.
The only other common X250 design fault I've fallen victim to is the failing dual mass flywheel problem. It failed after only 20,000 miles, 6,000 after I bought it. Pretty poor lifespan but I suspect Sevel don't design them to lug 5 tonnes around and that 3.0 litre unit has an awful lot of torque. The converters take no account, figuring it will probably last 5 years of most folks use and that's past the end of their responsibility. Thank heaven the van was still under warranty. It was a £1500 exercise, though £150 was from my pocket because of me insisting on the Borg and Beck solid flywheel conversion. Whoever gets that truck has a well-sorted power unit.
X240s? My previous truck was one and I'd guess you have no problem with an overly high 5th gear, trying to pull 5 tonnes. That was the only annoying thing about that power unit but, somehow, it just never annoyed me enough to change the 5th gear set for the low one.
Will
 

snail

Well-Known Member
Hi Will, well done for raising it on this forum others may not be aware? dual mass flywheels are good for smoothing out the drive till they fail, expensive! so you opted for the standard replacement? can you notice any difference? we don't have a dual mass on the 240, lots of 4x4s have them as well.

Our hymer being on a fiat heavy duty chassis has a lower ratio diff so its all good with the 2.8 stronger drive shafts as well on the heavy chassis, I thought that would of been standard on yours guessing its a tag axle? think ours is toward the end run of this chassis as 244..... seems by then it was mostly sorted? 47,ooo now, 250's started with bad press, clutch judder, water ingress on bonnet, wiring etc, always wanted the 3 litre on a Chieftan but just dreams ours has served us well since buying it new so seems really silly to buy someone elses cock up second hand?

The fiat forum can be useful to look through as well for all base vehicle faults

snail
 

Willum

Active Member
.......... dual mass flywheels are good for smoothing out the drive till they fail, expensive! so you opted for the standard replacement? can you notice any difference? we don't have a dual mass on the 240, lots of 4x4s have them as well.snail
There is a noticeable reduction in the smoothness of the drive train if you try and accelerate in the higher gears below 1500 RPM. It's an easy 'work-round' though. You just teach yourself to use the box more, As a general principle it's kinder on the power unit and drivetrain, anyhow.
As I understand it, all the 3.0 litre lumps have a dual mass flywheel, as do a great many other vehicles on the road these days. It's not just the 4x4s, sadly, 'cos I've seen quite a few failures, even in relatively small engined saloon cars. No surprise that it's a favourite way to smooth out the lumps on an awful lot of diesel engines. The solid conversion I fitted is a new, special development, by Borg and Beck.
Will
 
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chrisjones18

Well-Known Member
I have the dual mass one.. biggest problem is that some do not know how to drive them.. they are too gentle on the throttle and don't push the clutch h pedal fully down when changing gear... it then gives problems when in too high a gear and low revs.I have had electrical problems..... due to a badly fitted alarm system.
 

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