V6 starting issue.

[dunk]

Evening all, The V6 has developed an annoying trait, as in it some times won't start, it's a bit odd and seems to relate to being parked in warm sunsine. When you turn the key, first thing in the morning on our shady drive way, you get a full compliment of warning lights and it starts perfectly, wait a little later in the day when the sun has shone on it for a bit and you just get the battery warning light and no attempt to start at all, wait for the shade to come around couple of hours in the shade all back to normal and starts fine, If engine is warm it's exactly the same starts fine in shade, parked on the sunny road, nothing! (bit odd) This morning, having returned from 2 weeks away started on the button in the shade, drove daughter to nursery (about 3 miles) stoped, restarted fine, drove to inlaws, (3 more miles) stoped started fine, drove home (1mile) parked up 4 hours later nothing! bet your life when I get home in an hour or so it will start fine! bit flumuxed, I've checked all the fuses all are ok, cleaned up a load of earths, replaced the battery earth terminal cos it was cracking, but the problem still occures. Any thoughts gratefully appreciated.

Dunk

[dunk]

forgot to mention it's a V6 Xantia

[Mandrake]

Have you done the starter helper relay modification ? It seems to be something that all the V6's need sooner or later, although usually the symptom is the starter solenoid clicks but the starter doesn't turn over.

[Mandrake]

Just a clunk from mine when key turned, nothing from the starter itself. Hasn't failed once since it was 'relayed'

The clunk does come from the starter solenoid on the side of the starter - it moves, but not far enough to close the contacts and provide power to operate the starter.

If none of the dashboard lights except the charge light are coming on though, there must be something else wrong as well, perhaps dry soldered joints in the fuse box ?

[xantia_v6]

Tat would be my old car, a true workhorse. It has had the relay mod done, but if the warning lights (and gauges) are dead, then it sounds exactly like the fault my current Mk1 V6 developed last month.

see here for details.

If this is the same fault, you need to replace the fusebox under the dash, or take it out and resolder the connections between the 2 PCBs.

The same fusebox is used on all MK1 Xantia that have the fog light switch on the stalk (not the dashboard), funny that the failure is on 2 V6s (which were built 3 months apart).

Mike

[dunk]

Thanks Mike, this dose to appear to be the problem I've sourced a replacement off the bay, & fitted it, quite tricky with my sausage fingers! The interior lights that didn't work now do, the air con works much better, the idle is better, i think the gear change is better, and most importantly it has started perfectly about 50 times so fingers crossed, duff batch of fuse boxes I guess, hopefully the soldering was better 18 months earlier.

Dunk.

[Mandrake]

Thanks Mike, this dose to appear to be the problem I've sourced a replacement off the bay, & fitted it, quite tricky with my sausage fingers! The interior lights that didn't work now do, the air con works much better, the idle is better, i think the gear change is better, and most importantly it has started perfectly about 50 times so fingers crossed, duff batch of fuse boxes I guess, hopefully the soldering was better 18 months earlier.

Interesting to hear that the idle and gear change both seem better, what was wrong with the idle before, was it an intermittent miss ?

I've been chasing intermittent engine running issues for 9 months now and have also had sporadic gearbox issues, I've tried so many other things that I'm wondering if its time that I lifted out both the interior and under bonnet fuse boxes and re-soldered all the soldered joints.

How easy is it to get the fuse box you replaced out far enough to resolder the joints ? Also does anyone know if there are any soldered joints in the under bonnet fuse box and if so how to get at them for re-soldering ?

[addo]

The fuseboxes all unplug or unclip. The little slave panel under the bonnet has two yellowclips you pull outwards to release the connectors. Under dash you pull the red tag out a quarter inch, then slide the fusebox upwards a similar distance with a good push. You can then pull it out about three inches on the harness and unclip each plug.

The maxi fuses are on sort of bus bars, any fault would be easy to observe once you unclipped it and pulled upwards for inspection.

[xantia_v6]

Good to hear that it is sorted.

Once you have the fuse panel out (which is quite fiddly), it is easy to resolder the pins around the edge of the PCBs, which (at least in my case) were the bad joints.

I think that the joints were probably OK at the factory, but thermal stresses (external and internal) cause metal fatigue in the solder, which will eventually fail, leaving a high resistance or intermittent contact.

The circuit that causes the instruments and warning lights to fail on a Mk1 (F12) does not power the engine or transmission ECUs, but does power the starter inhibit relay and gear lever interlock (hence the no-start on a V6). It is possible that another circuit was failing (but the ECU fuse in in the other fusebox).

[Mandrake]

The reason I ask is way back last year I noticed an intermittent miss at idle that seemingly began right AFTER I had the under bonnet fuse box apart to do some recon work for the starter relay mod. I didn't actually fit the relay at that time, nor did I disconnect the fuse tray - I just had the tray for the three relays on the left lifted out, and the fuse tray section lifted out and tilted back.

After reassembly I noticed an intermittent missfire at idle that I had never seen before that time. Since then that idle misfire has come and gone intermittently, twice I've cleaned all the fuse and relay sockets and it has gone away but then returned after a while, I didn't realise there were any soldered joints in the fuse boxes but if there are perhaps I'm looking at a dry joint ?

On my Mk2 V6 the permanent (memory) feed to the engine ECU is in the drivers foot well fuse box and so is the main feed for the gearbox ECU, so I really ought to check that one for dry joints as well...

[dunk]

I'm guessing that the new earth clamp & cleaning up all the earths by the battery may have improved the idle before it was falling out and near stalling now it has a strong steady idle, the gearbox seems much slicker, that said I have just driven 3000km in a laiden AKS 400 with a crap box, so my perception of gearchanges may be a little squewed, I've opened the old box and several joints look quite dry to me to the naked eye, I have no magnification but a few look rough, Interestingly the box has 24/05/99 printed on it which suggests to me It's not the first time the fuse box has been changed.