MY2001 XJR smoking on WOT
Discussion
Hi, wonder if anyone can help.
History
I have an MY2001 XJR, bought in December 07, currently with 73k, I have had the timing chains, tensioners, guides etc. replaced, inspection showed excessive play on driver’s side. I got the newer water pump fitted and a new pressure cap and thermostat at the same time, as a precaution. I also had the gearbox fluid and filter changed as well as new front disks and pads. The diff input seal was shot, so the input shaft was replaced, I believe that the seal is not available separately.
I still have to get the rear disks and pads done and am pretty sure I am up for some suspension bushes to be done soon also.
The car uses no oil whatsoever, it has not moved a bit on the dipstick since December and about 4000 miles. I have checked after it has been parked up for a while and it leaves no sign of any dropping fluid.
I never really pushed the car hard, until I had the work done above, it drives like a dream, apart from one small thing that has now happened twice.
Problem
Both times the same scenario, outside lane of the motorway, 70-80mph, if I try rapid acceleration (WOT), car changes down a gear, supercharger gets loud, car begins to really motor, smoke appears out of the back, quite a bit !, no loss of power, smoke goes away fairly quickly. If I try the same but from slower speeds there is no kickdown on the box, no smoke whatsoever and then I run out of road.
Is this possibly un burnt fuel getting dumped out into the exhaust when the car kicks down to 4th gear and the revs spin up, or is it something more sinister. No smoke at any other time and it does not use oil, uses a heck of a lot of fuel tho
Many thanks in advance
Col
History
I have an MY2001 XJR, bought in December 07, currently with 73k, I have had the timing chains, tensioners, guides etc. replaced, inspection showed excessive play on driver’s side. I got the newer water pump fitted and a new pressure cap and thermostat at the same time, as a precaution. I also had the gearbox fluid and filter changed as well as new front disks and pads. The diff input seal was shot, so the input shaft was replaced, I believe that the seal is not available separately.
I still have to get the rear disks and pads done and am pretty sure I am up for some suspension bushes to be done soon also.
The car uses no oil whatsoever, it has not moved a bit on the dipstick since December and about 4000 miles. I have checked after it has been parked up for a while and it leaves no sign of any dropping fluid.
I never really pushed the car hard, until I had the work done above, it drives like a dream, apart from one small thing that has now happened twice.
Problem
Both times the same scenario, outside lane of the motorway, 70-80mph, if I try rapid acceleration (WOT), car changes down a gear, supercharger gets loud, car begins to really motor, smoke appears out of the back, quite a bit !, no loss of power, smoke goes away fairly quickly. If I try the same but from slower speeds there is no kickdown on the box, no smoke whatsoever and then I run out of road.
Is this possibly un burnt fuel getting dumped out into the exhaust when the car kicks down to 4th gear and the revs spin up, or is it something more sinister. No smoke at any other time and it does not use oil, uses a heck of a lot of fuel tho
Many thanks in advance
Col
Any other clues? Have you checked the oil, brake fluid and coolant levels? Is there any evidence of oil mist inside the air filter box or air intake trunking? Any signs of unusual or recent oil leaks from the engine? Is the air filter clean? Are there any indications of oil in the coolant, or coolant in the oil?
Grey or white smoke or steam usually suggests either coolant getting into the combustion chambers - unlikley I'd suggest as you say it only happens on hard acceleration - or possibly brake fluid entering the induction system via. the servo from a leaking master cylinder.
The other possibilies are the sump may be significantly overfilled and the pumping action of air moving round the engine at high load/RPM is splashing excess oil on the underside of the pistons and bores. Excess oil will defeat the oil scraper rings on the pistons and allow oil into the combustion chambers. There is also the possibility that some engine wear is allowing excess blow by from the combustion chambers pressurising the sump and forcing oil or oil mist through the induction system. In a bad case you'd have quite severe detonation (pinking) as oil mist in the induction air severely compromises the octane rating of the fuel. There is also likley to be unusual oil leaks appearing as excess crankcase pressure forces oil past the seals You may have a problem with the supercharger leaking it's lubricant into the induction system too.
You could simply be overdue an oil change. Mineral oil contains long chain polymer molecules which maintain viscosity at high temperatures. As the oil ages the polymer chains break down, allowing a 5W-40 oil to degrade to a 5W-30 - 20 - 10 and so on. As the oil thins, all other things being equal, it's more likely to enter the combustion chambers and become burnt.
Jaguar's 10k between changes using ordinay mineral oil is way, way too long IMO.
Normally oil combustion will result in blueish coloured smoke from the exhaust but depending on circumstances - exactly where and what's being burnt, and how efficently it's burning - it's possible it may appear grey or white.
I'd suggest you check all the levels. If they are correct, then the next stage would be perhaps a really careful look round the induction system for signs of oil mist or damaged or missing pipes.
Is there any evidence of steam from the exhaust when the engine is hot? If so you may have a head gasket failing.
With the engine hot and idling carefully loosen the oil filler cap and remove it just enough to allow pressure to escape - don't take it right away from the filler hole unless you really want a facefull of oil mist at 90 deg or so - there should be some positive pressure but not much. If it blows off with force, or there's lots of mist you have a crankcase pressure problem or really knackered oil.
Then perhaps do a compression check to see if you have any excess bore wear. Figures should be within 10% over all 8 cylinders.
HTH
Grey or white smoke or steam usually suggests either coolant getting into the combustion chambers - unlikley I'd suggest as you say it only happens on hard acceleration - or possibly brake fluid entering the induction system via. the servo from a leaking master cylinder.
The other possibilies are the sump may be significantly overfilled and the pumping action of air moving round the engine at high load/RPM is splashing excess oil on the underside of the pistons and bores. Excess oil will defeat the oil scraper rings on the pistons and allow oil into the combustion chambers. There is also the possibility that some engine wear is allowing excess blow by from the combustion chambers pressurising the sump and forcing oil or oil mist through the induction system. In a bad case you'd have quite severe detonation (pinking) as oil mist in the induction air severely compromises the octane rating of the fuel. There is also likley to be unusual oil leaks appearing as excess crankcase pressure forces oil past the seals You may have a problem with the supercharger leaking it's lubricant into the induction system too.
You could simply be overdue an oil change. Mineral oil contains long chain polymer molecules which maintain viscosity at high temperatures. As the oil ages the polymer chains break down, allowing a 5W-40 oil to degrade to a 5W-30 - 20 - 10 and so on. As the oil thins, all other things being equal, it's more likely to enter the combustion chambers and become burnt.
Jaguar's 10k between changes using ordinay mineral oil is way, way too long IMO.
Normally oil combustion will result in blueish coloured smoke from the exhaust but depending on circumstances - exactly where and what's being burnt, and how efficently it's burning - it's possible it may appear grey or white.
I'd suggest you check all the levels. If they are correct, then the next stage would be perhaps a really careful look round the induction system for signs of oil mist or damaged or missing pipes.
Is there any evidence of steam from the exhaust when the engine is hot? If so you may have a head gasket failing.
With the engine hot and idling carefully loosen the oil filler cap and remove it just enough to allow pressure to escape - don't take it right away from the filler hole unless you really want a facefull of oil mist at 90 deg or so - there should be some positive pressure but not much. If it blows off with force, or there's lots of mist you have a crankcase pressure problem or really knackered oil.
Then perhaps do a compression check to see if you have any excess bore wear. Figures should be within 10% over all 8 cylinders.
HTH
Thanks for the advice, I had a good look around what I can see of the engine today and the only thing of note is that the cap that should cover the pipe where the dipstick for the auto box should be is missing.
Is it possible that on kick down, at speed, there was a surge of auto box fluid up this tube? Is it okay to drive the car, at low revs with this cap missing and has anyone priced up how much the auto box dipstick on the XJR is?
Is it possible that on kick down, at speed, there was a surge of auto box fluid up this tube? Is it okay to drive the car, at low revs with this cap missing and has anyone priced up how much the auto box dipstick on the XJR is?
It's possible. Although you're more likley to see smoke from burning oil that's leaking onto the exhaust at a standstill from outside the car.
If oil has leaked from the 'box it may have run onto a hot exhaust and burnt off externaly. I'd expect to see evidence of transmission fluid all over the rear of the engine though, and if there has been a loss of fluid then obviously get it checked as you risk damage to the gearbox by running it with a low fluid level.
Even if this is not the problem, I'd replace the cap as soon as poss. to avoid any contamination entering the gearbox.
If oil has leaked from the 'box it may have run onto a hot exhaust and burnt off externaly. I'd expect to see evidence of transmission fluid all over the rear of the engine though, and if there has been a loss of fluid then obviously get it checked as you risk damage to the gearbox by running it with a low fluid level.
Even if this is not the problem, I'd replace the cap as soon as poss. to avoid any contamination entering the gearbox.
Sorted, it was the gearbox selector seals that were leaking slightly, kicking down at speed caused it to leak a lot more rapidly and vaporise when it hit something hot, hence the smoke, £1 for the part, £26.90 for the missing fluid and £1.77 for the filler cap, + labour.
Many thanks
Cecil
Many thanks
Cecil
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