I just bought this great 94 xj6, she runs good but at startup about 90% of the time I get a nice big plume of white smoke from the exhaust. When I shut her off he shudders a little. Am I looking at something severe, or could it be something simple. I'm getting a fuel smell when she's parked too, seems to be from the backseat.

Any help is appreciated.

 

hi beatle, do a search on the forums for 'white smoke' and you'll find lots of posts related to that symptom. It's a good start for you.

 

Hi there,
The fuel tank is located behind the rear seat but separated from the interior of the car by a bulkhead/firewall.
Open the boot/trunk, remove the spare wheel, then the cover trim behind the spare and you will see the fuel tank, you might want to remove the left side trim as well.

Have a good sniff to the middle/top of the tank, you might have a duff seal on the evap loss flange (large white plastic piece) or a badly connected/split line. Also with the fuel cap ON, carefully pour a small amount of water into the black rubber collar surrounding the filler neck. There is rain drain pipe in the filler neck it may have become disconnected or broken, allowing splashed fuel when you are filling the car to leak into the boot, if the poured water leaks into the boot then you may have found the problem.

White smoke after standing, not a great sign. Check your coolant level and oil level/condition. The smoke indicates that something other than just fuel and air are getting into the combustion chambers. (possible head gasket issue).

White whispy steam after standing when starting on a cold and frosty morning NORMAL but should go away when the car reaches normal operating temp (looking at your location I doubt this applies to you).

All the best,

 

Super helpful Translator, thanks! I'll check the fuel tank issue out this weekend, I love good troubleshooting tips like that! I'll get back to you all on what I find, I'm hoping its simple and not just a tank leak, I dont see weird signs of that in the boot but there is a weird carpet discoloration at what may be the base of the filler pipe, once I get that all out I can tell for sure and run that water test.

If it's a head gasket leak, which I kind of fear too, it wouldn't be too bad I don't think, the engine is strong but I do think it runs a little rich. I had a previous XJ40 for a brief time and it had a gasket leak but left the engine a mess, I don't see that here... of course that one had no smoke though.

Is the gasket expensive? Should I trust it to my mechanic buddies or take it to a Jag specialist?

Thanks!

 

Hi again,
I didn't say it was the head gasket. I said check your fluids. As H20boy said do a search on "white smoke"
Whilst cutting the lawns earlier a thread came to mind that had a whole host of the tech's involved over about 5 months. It reads a bit like a novel but you will see loads of good advice on "white smoke"

https://www.jaguarforums.com/forum/s...ht=white+smoke

I hope that it is not the head gasket but is in reality a fuel issue (stuck injector etc).

You need someone more experienced than me for this, Ken, Brutal, or one of the other Tech's.

 

If it's truly white smoke, see the above postings. More than likely, if it's only at start up, it's not a big concern. If it's blue smoke (and I will tell you, blue smoke/white smoke--looks the same to me) then you probably have oil dripping into the combustion chamber through the exhaust valves. Very, very common. Don't sweat it.

 

If you are lucky you could have a brake fluid problem. It goes like this; brake fluid leaks from the master cylinder around the actuating rod. On start up the vacuum from the brake vacuum booster draws the fluid into the engine and presto- white smoke.

It doesn't take much of a leak to cause the problem. Carefull monitoring of brake fluid usage may verify the problem and the old sniff test is usefull as well. Also feel around the bottom of the vacuum booster for brake fluid after the car has set over night. Wet fingers are tell tail.

The solution is a rebuild of the master cylinder or a new one. Do the above before involving yourself in complicated engine diagnostics. Hope this helps and that you lead a virtious life.

 

My fluids seem pretty consistent, no real change in level over the last week. I do notice however that the smoke seems to have a light blue tinge. I was hoping I could hold out until after the holidays to fix but I probably need to do it before it will pass smog certification this month.

The gas smell, I cleaned out leaves and stuff that gathered around the filler area, and there was a distinct release of air at one point and the smell has seemed to lessen since then. Hopefully a good airing out and it doesn't return.

 

OK, so I am going to bump this old thread. *BUMP*

I have been reading about smoke at start up on the XJ40. Most recommendations point to valve seals, leaking master cylinders, etc.

The one I have not seen mentioned is a crankcase venting problem.

My '94 smokes on startup. It does so because there is oil in the intake duct (flexible bit) between the MAF and the throttle body.

A few days ago I was doing some cleanup in the engine bay and removed the air filter box and MAF. There, pooled in the bottom of the duct was engine oil. Just above is the connection for the hose to the cam cover.

It became obvious that this is the source of the smoke at start up. How do I know? I cleaned the duct and installed it. For a few days there was no smoke on start up. Now it is back, as is the oil.

It seems like this is a crankcase ventilation issue. I don't have a good reference photo (the Haynes manual doesn't help) to see where the PCV hose(s) should be routed.

So I am looking for a good engine bay photo or a hose routing diagram to verify that all is where it should be.

-Mike O

 

Hi tarhealcracker,

On many cars this would be applicable but on a '94 XJ40 the brake power assist is hydraulic, not vacuum powered, so there is no vacuum fitting near the master cylinder that I can think of.

Cheers,

Don

 

Hi Mike,

The "Engine Breathing System," as Jaguar calls it, is designed to reburn crankcase blow-by gasses and to create a calculated degree of vacuum in the crankcase. An unfortunate byproduct is the large volume of oil and gunk in the vapors that are inhaled by the intake. This is also the source of the gunk that drips down into the TPS.

I'm not sure about your '94: if it has the oil filler cap in the cam cover, then it will be different from our '93; if it has an oil filler tube like our '93, then the following will apply:

The parts illustration at the link below shows the two main engine breathing hoses. One hose connects the cam cover port to the lower fitting on the oil filler tube. The other is a Y-shaped hose called the "Filler Pipe to Air Box" hose. The larger end of the Y connects to the upper fitting on the oil filler tube, the smaller end connects to the "coolant heated restrictor" (the part labeled "Refer to Engine," and the other end of the larger hose connects to the breather heater

Engine breathing hoses:
Engine Breathing-3.2/4.0 Litre - Parts For XJ6 & XJ12 from (V)667829 to (V)708757 | Jaguar Classic Parts UK

Oil filler tube with two fittings:
Oil Filler Pipe-3.2/4.0 Litre - Parts For XJ6 & XJ12 from (V)667829 to (V)708757 | Jaguar Classic Parts UK

If your car has the oil fill cap in the cam cover, then it is probably similar to the X300. The illustrations below are all I can find in the parts manual, and they're not particularly helpful:

X300 breather hosesand cam cover:
Engine Breathing-3.2/4.0 Litre - Parts For XJ Series from (V)720125 to (V)812255 (X300) | Jaguar Classic Parts UK
Camshaft Cover-3.2/4.0 Litre - Parts For XJ Series from (V)720125 to (V)812255 (X300) | Jaguar Classic Parts UK

Here are links to some potentially relevant photos of our '93:
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page

Cheers,

Don

 

Ditto. The valve stem seals are rubber and over time they harden and lose their seal (some claim they harden in a very short time and are hardly worth installing). Because the engine is canted toward the exhaust side, oil that pools beneath the camshafts leaks down the exhaust valve stems into the cylinders and causes the puff of smoke at startup. If your car runs fine otherwise, then by all means follow Ken's good advice and "Don't sweat it!"

If it was the head gasket causing the smoke, I think you would notice rough running and more smoke. The head gasket on our '88 failed once and our '93's failed twice (90K miles apart), and all three times there was an extreme loss of power and huge plumes of white fog from the tailpipes.

Cheers,

Don