Brief Encounter II - The Sequel

red_dwarfers · Unread post by **red_dwarfers** » 03 Mar 2009, 22:26

CitroJim wrote: I have a feeling my V6 will be back on the road sooner than initially anticipated

Im going to have to go on a roadtrip up to Milton in the summer

Unread post by **xantia_v6** » 07 Mar 2009, 18:29

On the failure mode of the pump, maybe a seal gets damaged, allowing the pump to suck in air, rather than lift oil from the sump?

My main question though, is what are the early symptoms of this type of transmission failure? or of a partially blocked oil filter?

Unread post by **CitroJim** » 07 Mar 2009, 23:08

xantia_v6 wrote: My main question though, is what are the early symptoms of this type of transmission failure? or of a partially blocked oil filter?

Not many I'm given to understand. The whine seems to be the main one as the pump is starved. And it seems they don't whine for long before bidding goodnight Vienna

If it whines, take that as a sign of almost imminient failure and get it looked at.

Another early symptom may be a whine on start-up or a delay in taking up power when cold.

Ekaftan has raised a very good point about the torque convertor lock-up clutch being the primary cause of gearbox failure. It seems, bourne out by a bit of research today, that the lock-up cluch friction lining breaks ups and the bits end up swilling around the gearbox and clogging the filter and cooler. The torque convertor is a sealed unit and impossible to see inside of (except perhaps with an endoscope) or effectively flush so as a precaution, I'll replace mine with my spare. My spare has been out in the rain for a time but luckily upside-down so no water has got inside. I'll also change the transmission cooler for the good one from my spares 'box. I have a brand-new filter.

Progress on the removal of the duff gearbox from my V6 has been very good today. The first job was to remove the RH driveshaft. Mindful of John's (jgra1) adventures in this department, I approached the job with some trepidation. It's not easy as one "hockey stick" (Intermediate bearing retainer) nut is very hard to reach or even see on account of having an exhaust system curling around the driveshaft! However, a socket on the end of a long extension plus a universal joint and another extension undid it and the last task of checking and setting the hockey stick disenagaged can be done from the wheelarch with a cranked ring spanner, just.

That done, it was time to see if the driveshaft would move. Nope. Stuck fast

They can stick not only in the intermediate bearing housing but also on the gearbox splines. Unlike a manual, these autos have dry driveshaft splines and the driveshafts can be removed without spilling oil. This of course means that rust can build up on the splines and stick it fast.

Another problem is one of access, it's hard, due to the presence of the aforementioned exhaust system, to get good purchase on the bearing collar with anything to apply useful blows to it. However, I have a long, thinnish cold chisel about two and a half feet long. I could angle this up against the collar and manage to give it whacks from a club hammer. With a douse of Plus Gas and a good helping of Citronut's Percy Whatsit, I was successful. It still took a good hour though.

Enough of lying underneath for now. Next on the list was the inlet manifold. That's an easy enough job. When I removed the manifold I could smell petrol and found the inlet tract quite wet. It last ran about two weeks ago briefly, just to raise the suspension to get it on stands. I also noticed it only had half a manifold gasket

On the V6, the manifold needs removing to do the sparkplugs in the rear bank so it's doubtless been off a few times in the life of the car. I'm sure though that the missing gasket could not be good and the mixture must have been upset.

Next off was the LHM reservoir and I was pleased to see it full of squeaky clean LHM and spotless filters

Unlike most Xantias, the reservoir must come off in the V6 when removing the gearbox. Not only does it give a bit more access generally but it also allows the ABS block mounting tray to be removed. This too is esential so that the ABS block can move sideways to give access to the gearbox mount. It is impossible to reach it otherwise. Luckily, no need to disconnect any ABS block pipes

They flex far enough to expose the mount.

The last job today was the removal of the hydraulic pressure regulator. This is different on the V6 as it hangs off the gearbox upside-down like a roosting bat. Access loks terrible but like so many things on a Xantia generally and a V6 in particular, it will just allow itself to be removed. Just be careful when disconnecting fragile LHM return pipe.

Once again, my magical Pleiades tool came into its own for cracking off the accumulator; it's angled just perfectly for the job and as with most things in the V6, the sphere is hemmed in and not easy to get purchase on with anything else.

So far, everything I've needed to remove has been just removable despite the shortage of space and "shonehorned in" nature of the beast generally. Whoever packaged the V6 in the Xantia was a very clever person or maybe just a Tetris fan. Whatever, it works and what initially looks impossible usually turns out not to be, despite being far from straightforward!

Removing a pressure regulator is a messy job made worse by the sphere being upside down on it

The good news is that it looks like the starter motor can stay put. It's not bolted through the bellhousing like a conventional one.

Finally, a couple of pictures...

The first shows a general view of the engine bay with lots removed. The gearbox mount (goldy coloured donut) can now been seen and got to

This is a closer view of the rather more exposed gearbox

Almost sufficiently exposed now (I hope) to allow removal of same..

The only remaining snag are a few smallish coolant hoses blocking access to a bellhousing bolt and the TDC sensor; they'll have to come off.

The V6 cooling system is an amazing thing. lots of pipes and just visble in the second picture is a cream coloured spherical expansion tank in the cooling system piping below the main header tank up on the bulkhead. I guess it's some kind of expansion tank but who knows on a V6 quite what it is or what it's purpose is?

It's been a good day

In my next instalment, I hope to report the presence of a gearbox safely in the workshop being stripped to finally get to the bottom of the question of what goes wrong with them.

Stay tuned!

Unread post by **myglaren** » 08 Mar 2009, 00:21

CitroJim wrote:With a douse of Plus Gas and a good helping of Citronut's Percy Whatsit, I was successful.

Removing a pressure regulator is a messy job made worse by the sphere being upside down on it

Has anyone thought to patent that Percywhatsit ©, could be a good earner.

Maybe you should think of doing the same to the green hair conditioner Jim, would help to pay for the work to the V6

Good to hear of some progress, coming along in leaps and bounds now!

jgra1 · Unread post by **jgra1** » 08 Mar 2009, 01:52

hi Jim well done

I just hope it all comes out as planned ok

the coolant thing you mention is a bubble-breaker, whatever that is ..

I remember this being a little minor sod for engine removal...

Unread post by **xantia_v6** » 08 Mar 2009, 08:18

CitroJim wrote:
xantia_v6 wrote: My main question though, is what are the early symptoms of this type of transmission failure? or of a partially blocked oil filter?
Not many I'm given to understand. The whine seems to be the main one as the pump is starved. And it seems they don't whine for long before bidding goodnight Vienna If it whines, take that as a sign of almost imminient failure and get it looked at.

Another early symptom may be a whine on start-up or a delay in taking up power when cold.

I am trying to determine whether my Mk2 V6 has the onset of this failure, or something else.

The main symptom is that occasionally when pulling away from rest, the transmission lets the engine revs rise to 1500 or 2000 without transmitting any torque, and then half a second later, the transmission bites, bringing the RPM down and accelerating the car. It only does this when warm, and when the car as been stopped for less than about 3 seconds.

When I bought the car (80,000 miles), there was a bit of a whine from the transmission, but that has largely disappeared after changing 5 litres of transmission fluid (the pink colour of the old fluid indicated that a few litres of Dextron had been added).

I have driven the car for about 2000 miles in this condition, and it does not seem to have deteriorated, but I don't want to destroy it.

jgra1 · Unread post by **jgra1** » 08 Mar 2009, 11:23

Hi Xantia_V6

neither my 85,000 Xant or 97,000 Pug 406 have ever done this.... for what it's worth.. probably not want you want to hear

Unread post by **xantia_v6** » 08 Mar 2009, 16:56

jgra1 wrote:Hi Xantia_V6

neither my 85,000 Xant or 97,000 Pug 406 have ever done this.... for what it's worth.. probably not want you want to hear

Neither has my 140,000 Xantia V6... but it needs a timing belt, a header tank and an LHM leak fixed... and I need to reduce my fleet by one.

Unread post by **CitroJim** » 10 Mar 2009, 21:47

xantia_v6 wrote:...but it needs a timing belt, a header tank and an LHM leak fixed... and I need to reduce my fleet by one.

Sounds like a nice project for someone

Now who was after a V6? Toby? The timing belt is the thing that might put some off but it is doable. I have the official book of words on how to do it. A four and a half spanner job but doable. The header tank (same as the 2.1TD one) and the LHM leak are not biggies. Where's it leaking LHM from?

Whilst I await time and facility to do the final push of removing my gearbox and in need of some therapy this evening after a trip to London and back today (work, not pleasure

) I set about cleaning up the pile of components I've already removed and stashed away in the garage. I do find cleaning oily bits very satisfying

It now has the cleanest, shiniest pressure regulator you've ever seen!

Tomorrow I'll continue and give the battery tray a new coat of paint as at some point there was an acid leak that's lifted some of the paint.

Once the gearbox is off I'll then give it and the engine bay a good spruce up.

Meanwhile, I've stated to write some web pages on the 4HP20. Have a look at my Website. They're not complete yet and very much still a work in progress. I'll be updating and adding to them as work progresses.

Toby_HDi · Unread post by **Toby_HDi** » 10 Mar 2009, 22:34

CitroJim wrote:...Sounds like a nice project for someone Now who was after a V6? Toby?...

jgra1 · Unread post by **jgra1** » 10 Mar 2009, 22:53

great work Jim
you've got me thinking.. my speed sensor is playing up.. does that mean a valve block cover removal to get it out ?

(half way through site)

Unread post by **CitroJim** » 11 Mar 2009, 07:31

jgra1 wrote: ...my speed sensor is playing up..

Which one John? Did that come upon the DIAG run on Saturday? How did it manifest itself? Or did it find an issue with the vehicle Speed Sensor (VSS) on the final drive? That one is easy (relatively) to replace.

Yes, it is a valve cover off job for either the Input or Output Speed sensor. For the former, it can be changed without disturbing the valve block but the latter needs the valve block to be removed.

I don't immediately believe this can be carried out with the gearbox in-situ; certainly not in the Xantia. Also, the oil has to be drained and you have to ensure all around the valve block cover is spotlessly clean before taking the cover off. Then you have the impediment of the cooler water hose that runs across the cover and sheer room to work. As the 406 has no hydraulics, in that it may be possible and if you could tilt the car up high enough at the front to shift all the oil into the back of the 'box, you might be able to do the job without draining the oil!

As I say, I'm interested to know what error the speed sensor flagged up...

jgra1 · Unread post by **jgra1** » 11 Mar 2009, 09:08

ahh.. I think its more an issue with the vehicle spped sensor Jim,. Since day one the speedo drops in and out of action, taking the variable power steering and the trip computer with it

the spare gearbox will have another sensor, so I may try that first ..

http://2.bp.blogspot.com/_2fj8MH_LeQ0/S ... +probs.jpg

Unread post by **CitroJim** » 11 Mar 2009, 20:29

Ahh, now I wonder if the root of the problem is with that magic box of tricks under the dash; the speedo driver ECU? It seems to be a bit of a failure point and used, to the best of my belief, only on the 406 V6 and the 406 2.0CT (Executive).

Not too pricey new apparantly....

The VSS is easy enough. Just watch it's removal as the green axle is likely to separate from the VSS itself and come out of position in the gearbox. You'll need a mirror on a stick to get it back in the right spot before dropping the cream part of the VSS back on top of it.

When I do the reassembly web pages I'll take a detailed photo of the boss in the casting when the end of the green axle sits...

Brigsygtt · Unread post by **Brigsygtt** » 12 Mar 2009, 01:15

Great thread Jim, im interested to see whats happened to the old box!