Noob saying "HELLO!" and a xantia question...

Nekkid · Post by **Nekkid** » 18 Apr 2010, 15:31

Hi all, what a friendly helpfull site!
I've recently upgraded to a 1997 1.8i xantia (from a 1973 Volvo 145!) and have a little problem with the speedo. I have found and read lots of speedo articles, but none of the problems exactly matched mine, so I thought I'd ask.

When driving, sometimes when i take my foot off the accelerator, the speedo drops to zero, as soon as i get back on the gas it comes back up again. It's an intermittent problem (i.e. sometimes it works just fine) and the rev counter, although 'lumpy' works fine.

My first thought would be the 'dry solder' problems mentioned in other threads, but then why only when the gas is released?

Any thoughts or similar experiences greatly appreciated.
Thanks
Charley

Post by **CitroJim** » 18 Apr 2010, 18:14

Hi Charley and welcome

Friendly? Us? That's very kind of you to say so!

My first thought is that the rocking of the engine as you come on and off the gas is upsetting the wiring to the vehicle speed sensor which is mounted on top of the RH driveshaft boss on the end of the diff. It's hard to see and can be flet from below or spotted from the top. It usually has a heatshield around it.

It has a three pin connector on it and the first thing sis to check the connector is secure. Then check the wiring from it and ensure it's not being snagged by the gear change linkages and has been damaged as a result. Also, given the close proximity of the exhaust, it may have been heat damaged...

citroenxm · Post by **citroenxm** » 18 Apr 2010, 19:50

Jim,

Wasn't the Sensor moved to the Top of the bell house on later 1997 cars??

Paul

Post by **CitroJim** » 18 Apr 2010, 20:14

citroenxm wrote:Jim,

Wasn't the Sensor moved to the Top of the bell house on later 1997 cars??

Paul

The TDC sensor was Paul, yes, but I believe only in the diesels. I have a feeling the petrols always had the TDC sensor on the top of the bellhousing.

I confess here and now I was concentrating first on Charley's dodgy speedo.

Mind you, if the wiring to the VSS is iffy or damaged, the same part of the loom has the wiring that goes to the TDC sensor so both problems may resolve at the same time. However, given the car in question is a 1.8 petrol, the TDC sensor signal is pretty much essential for the running of the engine.

Charley, what do you mean by a "lumpy" tacho exactly?

Nekkid · Post by **Nekkid** » 18 Apr 2010, 20:19

CitroJim wrote: the vehicle speed sensor which is mounted on top of the RH driveshaft boss on the end of the diff. It's hard to see and can be flet from below or spotted from the top. It usually has a heatshield around it.

Thanks!
Would I find this from 'head under the bonnet' position, or 'lying on my back in the mud' position?

Nekkid · Post by **Nekkid** » 18 Apr 2010, 20:24

Hi Jim,

By 'Lumpy' I just mean that the needle doesn't move smoothly, it's a bit jerky. At constant revs it stays in the same place though.

Post by **CitroJim** » 18 Apr 2010, 20:38

Hi Charley,

In a 1.8, the VSS (Vehicle Speed Sensor) should be fairly easy to spot from above. Look downward from a point just to the left of the LHM reservoir and if you can see the end of the RH (long) driveshaft and inboard CV boot the VSS should also be visible just to the left of it. It may well have a metal heatshield around it and/or a shiny fabric sleeve.

To me, the way your tacho behaves is prertty much normal for a MK1 which being a 1997 model, I guess yours is. I noticed it when I first owned a Xantia that on say, changing gear, the tacho needle would very quickly move to the new position, there is very little damping on it and it does almost jerk. You get used to it!!

Nekkid · Post by **Nekkid** » 19 Apr 2010, 19:06

Thanks Jim,
I'll check that out.

vince · Post by **vince** » 20 Apr 2010, 22:19

Welcome Nekkid,

1973 Volvo 145.....awesome

Was it one of these?

If so.....they rock

Post by **CitroJim** » 20 Apr 2010, 22:30

vince wrote: If so.....they rock

Indeed they do

I have happy and fond memories of owning one just like that in the early 80s when I lived in Cyprus...

Mine was a white 1969 144. I loved that car to bits. The only thing that went wrong on it was the fibre timing gear broke ( a very comon problem apparantly) but one of the back-street engineering shops in Limassol soon made me a new one. Cypriots are very skilled engineers; tehy could make anything. Bet they could make an Activa ram if asked...

I used the Volvo as my everyday car in order to preserve my MG Metro as the Metro was bought new and duty-free to bring back to the UK at the end of my tour...