Smoking XJR-S 6.0L

[KPB060362]

I have a 1990 XJR-S 6.0L that has done 94500 miles and reguarly serviced. Everytime I start the car there seems to be excessive smoke from the exhausts. It is not apparent when driving but only when stationary. It is worse in the cold weather. It is not oil. I am sure the head gasket is ok, it is not an oily smell and the smoke is grey not blue.

Anyone else have this problem?

Thanks

Kevin

[GlennH]

Hi Kevin,

Possibly a daft question, but are you sure it is smoke and not just water vapour?

This cat is burning a lot of fuel (even at idle) so it does generate a lot of steam. It will be worse until it gets warm due to the ECU pouring extra fuel in when the engine is cold.
Does the problem go away when everything is up to running temperature?

In this cold weather I constantly get a nice plume of steam from each exhaust even at normal temperature, but I think mine is overfuelling at the moment. Yours may have the same problem, check the inside of the tail pipes, mine are covered in soot (sure sign of overfuelling), hopefully your ones are quite clean.

Regards,
Glenn.

P.S. Glad to see you got your log in problem solved.

[ng4xjs]

I too get a fair amout of water vapour from the exhaust in this weather (even when the engine is fairly well warmed up). Mine is running at about the right mixture and I have over the years just put this down to the norm!

Nick

[KPB060362]

Hi Gents

I've been away on business so have only just seen your replies. Thanks alot, very useful. My exhausts are covered in soot too. I have this motor in the garage at the moment having a full service and tune up. The guy at the garage says that my idle speed is a little quick 9750rpm) at idle when in gear, he is going to try and get it down to 500rpm. He too thiks the smoking is water vapour.

Regards

Kevin

[GlennH]

Hi Kevin,

Idle speed for a fully warmed up engine should be 650rpm when in drive and air con set to on. 500rpm is a bit too low and is likely to be lumpy.

I'd be interested to know if the tune up highlights an over-rich mixture.

Cheers,
Glenn.

[HerefordMark]

It's water vapour - mine does the same, and overfuels as well. It never gets really warm, which I guess is the cause. Going to change the thermostats soon and see if that fixes it.

[GlennH]

Hi Mark,
I wonder if your car has the same symptoms as mine:-
Temp gauge sits 1/2 way between C and N,
trip computer indicates average fuel consumption aroung 19mpg, but when you fill the tank you find you've only really had 15mpg,
clouds of steam and sooty tailpipes.
If so, and you still get good heat in the cabin, it may not be the thermostats. I thought I had a temp gauge or temp sender problem, after changing the sender and measuring the circuit with no fault found, I eventually bought an infrared thermometer. It proved the stats were working fine (88 deg. C), but there is a cold spot (75 deg. C) where the temp sender is located. I'm still trying to work out why, but for the moment I've stopped worrying about the low reading on the gauge. Much less worrying than an overheating V12.

[HerefordMark]

Hello Glenn, fellow XJRS martyr...!

Yes, pretty much the same symptoms, and I did wonder about the temp sender. I'm not sure what would cause a cold spot - air in the system? Is it still the same after a long run? Anyway, I will go ahead and change stats on mine as there is no cabin heat at all, and I am changing the coolant anyway. If that doesn't work, I'll look at the temp sender.

HM

[GlennH]

Hi Mark,
Yesterday, I took my XJR-S to an independent Jaguar specialist in Peterborough. He's had some experience of XJR-Ss and is going to give it a service and thorough check up. While chatting with him, he told me the temp gauge should read exactly where mine does, about 1/3rd the way up. It is normal for an XJR-S. He went on to say that the needle will only venture close to the N on a hot day, stuck in traffic with the aircon on full blast! If it ever gets to N, it's a sign of a problem. He knew about the cold spot but didn't know the reason for it. I don't think it's trapped air because it never changes.

I get plenty of heat in the cabin, so it does sound like we have a different problem (or set of problems...).

When you say no heat at all, do you really mean zero heat or just luke warm? Zero heat isn't going to be the stats, you should get some heat even if they are jammed wide open, sounds more like a stuck control valve in the water feed to the heater or misbehaving blend flaps stopping the air getting to the heater matrix. There's a thread in the cooling section of this forum and I've seen plenty of comments about these on the Jag-Lovers forum.

It's good to find a fellow sufferer of XJR-S'itis. I'm not sure I qualify as a martyr yet, a bit impoverished perhaps I expect I'm about to be further impoverished when the bill comes next week
Still, we can't let these rare beasts disappear can we? It's our duty to posterity

Good luck with changing your stats. I'm told the secret is to refill very slowly.

Cheers,
Glenn.

[HerefordMark]

Hello Glenn,
Have been out working on the thing today. Still the same problem, the gauge is barely off the mark, the air is nearly warm, but nowhere near what it should be. I'll change the stats anyway (see cooling section for more on this!) and see what happens. Interesting that you mention 88 deg C - that's what I think they should be, but Dave Marks has suggested getting 82 deg C. I think 88 is the way to go, and will change them once David Manners sends me the right bits. Funny enough, the gauge went to 1/3 up in the first couple of minutes, then once the car warmed up a bit more it dropped away completely. Maybe the car has 82 stats fitted? It's definitely not the water valve, that moves OK, and all the flaps etc seem to move as they should. There's just no heat.

I changed the oil today - the service records with the car suggest it was last filled with 10W40, although the manual says it should be 10W60. So I took the plunge and used Millers Oils CRS 10W60 motorsport oil. What a difference - smoother, quieter, significantly more oil pressure. It wasn't cheap at £100 for 11 litres, but I ordered on line from Demon Tweeks, it got here quickly, and I'll soon forget the cost...!

Will be doing some more fiddling over the next few days, I'll let you know how things go. As you say, we need to stick together - I haven't found anyone who really knows much about these cars, although plenty claim to.

[GlennH]

Hi Mark,

Now that really does sound like thermostat troubles.
I've also heard of 82 deg stats being recommended, but I can't see any benefit to it unless you live in a much warmer climate than ours. I'd stick with the 88 deg ones too. The time to reconsider is when Wales becomes sub-tropical due to global warming

Millers 10W60, very nice. You certainly know how to pamper your V12. That's a racing oil isn't it? It sounds like it had a good effect on your engine. Interesting your manual recommends 10W60, the manual with my '89 car suggests anything from a 10W30 up to a 20W50 or a 5W50 if you are going for extremes of climate. No mention of a 60 weight at all. I wonder if Jagaursport changed the spec, or 60 weight multigrades suddenly became available on the market?

I know what you mean about lack of expertise on these cars. I've been doing a lot of research since getting mine. So far the two best sources of knowledge have been the Jag-lovers forum and the Jaguar Daimler Heritage trust. JDHT can supply the manuals on CD ROMs. The standard XJ-S manuals cover most things, but there is a further CD covering what little additional material Jaguar and JaguarSport published for the XJR-S (some of it drawn by hand!). They are well worth getting if you're going to be fettling the car yourself. Jag-lovers has been going for a long time and has a wealth of info, although I have high hopes for our own little forum here. There are quite a few XJR-Ss on the register so we are not alone. I went to the JEC XJ-S seminar last year and David Marks also showed a good knowledge of the XJR-S in his presentations, even if he does like cold stats.

[HerefordMark]

Hi Glenn,
The XJRS supplement with my owners manual recommends the original Castrol Syntron 5W50, which was an oil produced especially for these cars. The XJRS CD ROM mentions that this was later supplemented for Castrol Formula RS10W60, and this is indeed what the Castrol website recommends for the car. I guess they realised that producing an oil just for 1 car might be less than profitable! I did try getting some RS, but it is hard to get - Castrol have discontinued it in favour of the new EDGE range. The Millers is indeed a racing oil, and seems to do the trick.

Today's little session was interesting - the car's horn was not working so I removed the front spoiler/bodykit assembly to get to it. Sure enough the horn was a cheap replacement fitted years ago, and it had given up the ghost. Of more interest was the rust in both lower front wings where you can't see them under the bodykit. Should be a relatively easy fix with a bit of glass and hammerite, but I could have done without it. Also could have done without seeing that the bottom hose is almost shot. I'll have to renew that as well, and it looks as if access will be tricky. Don't say anything about 'well, that's the pleasure of old cars, isn't it?'

So I guess replacing the stats is going to end up as a major cooling system reurb. If the bottom hose is shot, so will the rest be. Oh well. Incidentally, I'll be using the 88 deg stats - I suspect the Zytek ECU is smart enough to figure out that the signal from the coolant temp transmitter is a bit low, and will permanently overfuel to compensate. 88 ought to be fine.

HM

[GlennH]

Don't say anything about 'well, that's the pleasure of old cars, isn't it?'


Hi Mark, I wouldn't dare say such a thing... I have worked out that lifting the bonnet or looking too closely at any part of these cars is very injurious to the wallet. I had a call from the garage today to tell me my car has the wrong spark plugs, the wrong brake pads, split brake caliper seals and worn out anti-roll bar links and bushes. This is even before they investigate the overfuelling problem. Scary what a little service can throw up.


So I guess replacing the stats is going to end up as a major cooling system reurb. If the bottom hose is shot, so will the rest be. Oh well. Incidentally, I'll be using the 88 deg stats - I suspect the Zytek ECU is smart enough to figure out that the signal from the coolant temp transmitter is a bit low, and will permanently overfuel to compensate. 88 ought to be fine.

While not wishing to add to your workload, you might like to remove the radiator while you have the cooling system apart. At the XJ-S seminar last December, David Marks warned that the radiator fins get blocked by all sorts of rubbish that gets trapped between it and the aircon condenser. Eventually it will result in overheating. I guess flushing the core wouldn't hurt either.

You're right about the ECU, it uses the signal from the temp sensor on the left hand thermostat housing to modify the fuel mixture. The sender on the right hand bank feeds the temp gauge only. I agree 88s are the way to go.

Sorry to hear about your attack of metal moth, at least it's out of sight...
Have fun.
Glenn.

[HerefordMark]

Hello Glenn,
We may have to discuss your definition of fun, but I know what you mean! See my posts elsewhere - radiator cross member, under all the loose oil and dirt, proved to have gone west as well. I was going to leave the rad, as it is quite recent, but I guess it will have to come out now. I have read that the cross member can be replaced by lifting the rad, rather than full removal. We'll see how it goes.

Sorry to hear about the work you need to do - can you do any of it yourself to save cash? I stripped and rebuilt the whole braking system on mine last year, inc the rear calipers (apparently they make the Guantanamo Bay prisoners strip an XJS' rear brakes in order to make them talk...). If I can offer any advice, let me know.

Incidentally, I went for a combination of DOT 5 fluid, Goodridge hoses and Greenstuff pads and have never had such good brakes on a car before. Even the MOT tester was impressed (although not with anything else..)

HM

[GlennH]

Hello Mark,

You have a point, there's nothing in that list of jobs that I couldn't do myself to save some cash. However, although my definition of 'fun' is perhaps a bit twisted, it doesn't extend to fettling old motors on my driveway when the temperature is at or just above freezing. Been there, done that in my younger, poorer days when I had to fix whatever old heap I was running at the time in order to get to work the next day. I recall being snowed on at 2am one night while I rebuilt the front hub on a Rover SD1. There's 'fun' for you. These days I take the lazy (but costly) approach in the winter months, hence the mounting garage bills...

I'm also sorry to hear about your mounting troubles. Going from a defective horn to a cooling system rebuild and the rest is rough. I don't think I dare take off the front spoiler.

I've heard that working on the rear brakes is a real pain on these cars, you can either see what you're trying to work on, or you can touch it. You can't do both. If ever I am overcome by the urge to tackle them, I'll drop you a line.

Interesting you are using Greenstuff pads. Are they as grippy as the Jag items and as dust free as they advertise?

Cheers,
Glenn.