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Puff the magic Jaguar!

I’m driving a 1994 Jaguar XJ6 Vanden Plas.

After 1 hour or more of standing, on restart the car emits a massive puff of blue-grey smoke for about 1 minute. The smoke then virtually disappears. Previous experience would indicate that this is a failure of the valve stem oil seals which allows oil to leak down into the cylinders while standing This burns off in the initial minute or so after restart.

My question - can the oils seals be replaced without removing the cylinder head? I have not been able to answer this question by referring to the maintenance manuals - they all assume that this job would be done with the head removed.


I don’t know about a Jag, but people do replace valve stem seals with the heads on other types of cars. They pressurize the cylinders, one at a time, with compressed air through the spark plug hole, when both valves are closed and that holds them. Then they can work the new seals off and on the stems.

Is this a overhead cam engine? more complicated than doing your Chevy small-block.

Price the job (if not doing it yourself) see if it would be better to combine a valve job (with new headgasket)

It would be irritating to put new stem seals on and still see smoke, the quanity “massive” and the time “about 1 minute” makes me feel something more is wrong.

What you’re discribing is common with the AJ6 engine. Check the head gasket, on these cars it’s been known to fail. My mother had a 1994 XJ12, Styling was a little questionable but it drove magnificently. It was in the shop a good 3 monthes out of the year though.

FoDaddy, It Sounds Like Jags Are Not For Everybody
That must be one mighty fine, magnificently driving car if the styling is not so hot and you can only use it 3/4 of the year, on the car’s schedule, and then work and pay for repairs the other 1/4 of the year. When it’s percolating the driver must really be “fart’n through silk”!

You are correct. After a decade or so of putting with this, mom decided to get something more reliable. She now drives a Volvo C70 convertible, so far it’s been an order of magnitude more reliable than the Jag ever was. I suspect it’s mostly because the Volvo isn’t hobbled by Lucas electrics.

Oh Wow, I Forgot About Lucas Electrics!
I had a couple of run-ins with them 20 or 30 years ago, cars and bikes.
You mean they never got all the “bugs” worked out of every single piece of electrical hardware they ever made? Why don’t they just copy a successful company’s stuff?

Ah, Lucas Elecric, the Prince of Darkness. This is the company’s official nickname in Britain. Ford actually improved the Jaguar’s reliability by getting tough with their suppliers. However, reliability is a moving target, and Jaguar’s improvements were very slow indeed.

Movie star Clark Gable bought the first Jag XK120 in 1949. It overheated in LA traffic. It took till 1963 for the XK E, 3 models later, to have dual cooling fans to finally solve the overheating problem.

Thanks for your response. Yes, I have done this myself on a less “exotic” car. Looking through the oil filler opening, however, it looks like the valves and springs are sunk into the casting and with the camshaft directly on top it seems that compressing the valve springs and getting down to the oil seals would be a major challenge. That was the basis for my question. If I have to remove the camshaft etc, I might as well remove the head and do a more extensive overhaul.

Yeah. If I didn’t work on it myself mine, too, would be in the shop 75% of the time. So far, however, problems have been mainly electrical, A/C, and door locks and I have managed to fix them myself. The Jag is a beauitiful car to drive - but not for the average Joe unless he has a local Jag dealer and a potfull of $$'s.

Since it’s a DOHC unit, probably better off pulling the head (assuming that’s not too tricky, I have no idea) and having a Jag-familiar shop rebuild it.