Xantia V6 broken exhaust (update: and rough low rpm running)

[RichardW]

And my mate's got an engine crane, and there's plenty of room on my drive to hoik the engine out....SWMBO won't mind. Much

[Ben82]

And my mate's got an engine crane, and there's plenty of room on my drive to hoik the engine out....SWMBO won't mind. Much

You might want to wary of this offer Simon.... Reason:

[RichardW]

It's even the right colour!

[Chris570]

The V6 engine isnt really that hard to lift out. Just watch what you're doing a bit more. I've gotten pretty good at doing the XM one which is the same.

Should be easily do-able in a day.

Just gotta get a crate of tea and biscuits in and start at 8am, it's not as bad as it sounds, I'd rather lift the v6 engine out (then do some lovely underbonnet work while it's out) than do a heater matrix and clutch job

[Mandrake]

Simon, easy way to see if it's overheating. Take it for a ride with the Lexia and note the gearbox temperature at regular intervals and during a good thrash..

Yes I'll need to do that. Any idea what the normal temperature range is though ?

I get the impression that if its thrashed on the motorway for a long enough period of time (30-40 minutes) that it should settle somewhere in the 100-110 degree range ? I've seen 105 degrees before (many months ago now) when giving it a good hard thrash on a country road, but I haven't checked it recently.

From what I can gather from the service manual the two protection maps kick in at 118 and 120 degrees (for city and motorway driving respectively) and another more severe/emergency level of protection kicks in at 125 degrees. What the manual is unclear on is at what temperature it starts to favour locking up the torque converter more frequently, it says it does it, but not at what temperature... this may occur below 118 degrees as one of the first symptoms I notice when its fully hot on a long trip is that it will no longer unlock the torque converter when you give it 50% throttle, it just stays locked up until you give it enough throttle to kick down a full gear. As the torque converter unlocking under acceleration gives a good extra kick in performance through torque multiplication this is probably part of the reason why it starts to feel a bit lethargic in these conditions when it no longer does this.

Since the cooling comes from the engine coolant it can't be any cooler than about 10 degrees hotter than the coolant temperature, what is the correct coolant temperature for the V6 ? 90 degrees ? That would put a lower bound on the gearbox oil temperature of about 100 degrees, and I think I have seen mention of "approximately 100 degrees" as the oil temperature for the gearbox in the data.

The offer remains open. You get the gearbox to me in a clean condition and I'll rebuild it for you at cost... You arrange transport to and from along with a TC refurb and I'll do the rest. I won't lift engines or have the car here. Only a bare and clean gearbox.

How's that?

That's a very generous offer Jim, (and others) but pulling out an engine and gearbox is totally beyond my means at the moment. I'll have to try to make do without pulling it out. If I can identify a cooling problem then I might have finally found what caused its problems in the first place. If I catch it soon enough it might be spared from any permanent damage, although it might require another series of oil flushes if the oil has been burnt. At least I'm an expert on changing the oil now, and this time I would get the 20 litre drum!

[addo]

I was hoping this would have got sorted while I've been away.

[Mandrake]

Sorry to disappoint!

[CitroJim]

You might want to wary of this offer Simon.... Reason:

Is that a dog we can hear in the background or is the person trying the V6 for size just getting unreasonably excited?

Simon, remember the 'box is effectively water-cooled so the temperature shouldn't be much above the coolant temperature...

Have you felt the coolant return pipe yet to see if there's water circulating through the cooler?

Also, whip it off and flush it. It's very easy to do. Just undo the two Allen bolts that hold the cooler to the 'box evenly and alternately and you'll be fine.

[Mandrake]

Hi Jim, no I haven't checked the hoses to the heat exchanger yet, when you say flush them I assume you mean disconnect only the coolant pair and flush the heat exchanger with a hose ?

I did do a bit of fact gathering with the Lexia last night however regarding temperatures etc. Here is what I found:

Engine coolant temperature when the car is cruising above 30mph (even cruising at 70-80mph) seems to settle at about 87 degrees (as measured by the Lexia) and spirited driving doesn't lift it much above 89 degrees as long as I'm going fast enough to have air flow to the radiator.

At much slower speeds in stop start traffic especially after going fast then slowing down the temperature rises fairly quickly to 98 degrees with the fans coming on at 97 degrees. When the fans do come on it does seem to take a long time to cool down below 90 degrees though with only the fans for airflow. Does this all sound normal ? Bear in mind my radiator cap is loose so as to prevent the split seam in the expansion tank leaking when pressurized...

Gearbox oil temperature during my test drive which was a mixture of urban, country road, motorway etc stayed between 98 degrees and 105 degrees most of the time, with the highest I saw being 108 degrees, only after prolonged heavy acceleration at high speed. Cruising at 70mph it stayed steady at 102 degrees. (under the same conditions the coolant was 87 degrees)

What I also noticed is that the main source of heat in the gearbox is an unlocked torque converter... should be obvious I guess, but the rest of the gearbox doesn't seem to generate much heat even under load when the torque converter is locked up, so its no wonder the ECU likes to lock up the torque converter whenever it can.

I found this out because I did a test drive with the gearbox fuse removed to test 3rd emergency mode (checking to see if the torque reduction signal was affecting the engine) in this mode the torque converter is always unlocked and the gearbox is always in 3rd gear.

I went on a fairly short stretch of motorway which is on a steep hill and pushed it hard up there checking the torque reduction figure on the engine ECU. When I pulled over (off the motorway ) to reconnect the fuse I checked the gearbox and the oil was already up to 108 degrees in that short (albeit spirited) 5 minute drive. Without the ECU to manage the torque converter lockup it looks like the gearbox could potentially overheat if pushed hard for long enough.

So in the testing I did last night I didn't really see any signs of overheating as 108 degrees was the hottest it got even when thrashed. The interesting thing is that I could NOT get the car to play up last night either. I was hoping to see the symptoms that we saw when driving to Loch Lomond recently where it got very lethargic and would't unlock the torque converter under acceleration, but it didn't do that, although bearing in mind that first trip was in the middle of the day on an unusually warm and sunny day, while last nights test was on a cold night.

In fact if anything the damn thing was going like a rocket last night when I was wanting it to play up I could be imagining it, but when I went for a final quick drive with the fuse back in AFTER the test drive with it in 3rd emergency mode, it seemed to be running even better! Almost flawless in fact, at least in terms of acceleration. I'm sure its my imagination but surely we couldn't have something silly like oxidized contacts on the fuse causing low voltage to the ECU (and electrovalves) ?

So what we have now are some temperature figures from when the car is NOT symptomatic.

One thing I was a bit unhappy about though is that the oil temperature on the gearbox is VERY slow to change in response to load. I thought it would have quite a thermal mass but whilst it heats up relatively quickly if you cane it with the torque converter lockup open (reaching 108 in a couple of minutes) it takes a long, long time to cool down...

After caning it up to 108 degrees and then going back to a steady 60mph cruise with the TC locked up the engine coolant is at 87 but it takes many minutes for the gearbox to creep back down to 105 degrees, which is 18 degrees hotter than the coolant. Eventually it will stabilize on 102 with steady 60mph cruising.

So perhaps there is still an issue with the heat exchanger even though on a cold night last night it wasn't heating up sufficiently to be symptomatic ? Perhaps I'm just expecting it to cool down too quickly, I don't have another car to compare it to.

Regarding the torque reduction reading on the engine ECU, with both the gearbox fuse removed (thus no torque control signal from the gearbox) and with the fuse fitted I was able to push it along hard up a hill with the torque reduction reading showing constant zero. On the overrun it goes negative -10 to -20 and it momentarily goes negative -15 or so when you floor the accelerator but immediately returns to zero and stays there even with full throttle acceleration.

So during last nights test it appears that the torque reduction figure was not interfering with engine performance, but bear in mind the car was not symptomatic last night either.

Other factors to consider are that I'm currently running on Shell V-Power which is 99 octane so if the torque reduction was due to engine knocking on 95 octane fuel it shouldn't be knocking now even with full timing advance! (And doesn't seem to be) Also the Wynns hydraulic tappet additive has been in for a while now and it really does seem to have quietened down the tappets.

At least I know now on 99 fuel the torque reduction figure should be zero even under full acceleration, it definitely was not a few weeks ago on 95 fuel and before tappet additive was put in.

So, do I still have insufficient cooling through the heat exchanger which only rears its head on long drives in hot weather ? Or am I barking up the wrong tree again...(and why does the car run so well when it's under scrutiny with the Lexia )

[CitroJim]

That's it Simon, Disconnect each end of the cooler and flush it..

Those temperatures look fairly OK to me but at the moment I can't confirm as the Xantia V6 is out of MOT and I have no access to the ECU on the XM

I'd say the slowness to change is normal. Remember you have 9 litres almost of ATF in there and a massive lump of metal. It's will heat quickly as oil does and the heating will be helped by the cooler as it has hot coolant flowing through it. A mass of oil that big coupled with a mass of metal that big and the cooler effectively also acting as a heater is going to mean the oil takes ages to cool...

You're right that most of the heat comes from the TC. Shame you can't look at it to see what colour it is. A bad TC will be rusty like an exhaust manifold from the heat it generates whereas a good one will look like shiny silver metal...

[Stempy]

Sounds to me like sticking in some decent fuel has done the trick.............

[Mandrake]

Sounds to me like sticking in some decent fuel has done the trick.............

And putting the right spark plugs in... The FR7DC+ were definitely too cold a heat range and were fouling up badly with the short trips I was doing. Now that I think about it they were recommended for LPG (as well as petrol) doesn't LPG burn hotter and need a colder plug than petrol ?

It was going like a rocket up the hills last night by the end of my test drive, there is no way the plugs are fouling like they were before when it was running that well.

Moral of the story, unless you really know what you're doing and are willing to experiment, stick to the exact type specified by the manufacturer... the FR8KDC are slightly more expensive but its all pennies compared to the amount of agro caused by the car not running properly and having to take the manifold off for about the 5th time...

There still must be an intermittent problem somewhere that wasn't manifesting last night though because it had the new plugs and V-Power in during the trip to Loch Lomond where it became very lethargic after about 30 miles...I'm still suspicious the gearbox might be overheating in certain circumstances...next time I'm going on a long trip I'll chuck the Lexia in the car so I can connect it if it starts showing symptoms...(I actually did have it in the car that day but didn't bother to use it. )

[isisalar]

A few years ago I used to run firstly a BX 1.9D automatic, and then a Xantia 1.9D automatic as minicabs in London. You can't get much more testing conditions than a 12 hour shift in London traffic. The BX started to complain by clutch squawking after about 6 hrs running. The solution suggested by a local specialist was an oil cooler about 1/2 the size of the cars radiator mounted adjacently. Together with a dose of trans lube this banished the clutch squawk forever and the gearbox performed faultlesly.
The Xantia misbehaved in the same way when I first got it but a fluid change and a dose of trans lube sorted that out and I ran that, with a couple of fluid changes for 100,000 miles.
IIRC the oil cooler wasn't that expensive and might be a way to bring down the temperature if thats what's needed.
Kind regards
Paul

[Mandrake]

Hi Paul,

When you say clutch squawk can you describe the noise a bit more and under what conditions it occured ?

For a while mine was making a groaning/shuddering noise when trying to accelerate at low speed in high gears, it went away when I did several closely spaced oil changes...my belief is it was the torque converter lockup clutch shuddering.

I'm not sure what gearbox the 1.9D uses though, maybe the 4HP14, does anyone know ? If so I think the 4HP14 only locks up in top gear unlike the 4HP20 which can lock up in 2nd, 3rd and 4th depending on the circumstances.

[addo]

With an AL4 the shudder arrives as pressure regulation starts to become faulty. I can readily imagine this applies to the ZF boxes as well, the main difference being their electrovalve design is perhaps more readily "flushed" than a Siemens item.