My 2004 s-type 3.0 has sprung an oil leak. I've heard that an oil leak can be caused by a number of things and I'm not sure what it would be. My car shakes really bad on start-up in cold weather and I was thinking it may be related. Why would oil be leaking?

Also, my car has been consuming an excess amount of gas. I'm guessing I get probably about 10-15 mpg. Is this related?
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Toyota motor manufacturing indiana

 

oil leak? possibilities:
IMT O Rings
Valve Covers
Oil Pan
Have you gotten under the car yet? If IMT O-Rings are leaking, you would see signs of oil on the passenger rear exhaust heat shield (US) and possibilty of a burnt oil smell as well. To check, wipe backside of passenger side intake manifold.


Unsure if any would be related to more fuel consumption.

 

imts are leaking, rough idle when cold, when it warms up they expand and seal better. poor fuel econ because youre getting unmetered air in the engine from a vacuum leak

 

So with new IMT rings the car would have a smoother idle?
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BATTLESTAR GALACTICA ADVICE

 

Thats what Brutal is saying. New green O-rings dealer only!
Check this out for replacement:
https://www.jaguarforums.com/forum/s...ad.php?t=32135

 

Back in September and October when our local dealership service department was chasing our S-Type's sporadic misfires in cylinder 3, rough idle at start-up was sometimes noted. But our IMT O-rings were not leaking oil at that time, at least not that I could tell. I think the replacement of our cracked air filter housing along with the new mass air flow sensor that came with the new air filter housing fixed the largest contributor to our misfire issue, but I also think that our factory IMT O-rings played a part in our misfires as well. The car has thrown no further misfire codes since then (early October and nearly 10,000 miles). I did notice some rough idle at start-up again in early January but attributed it to the 15 degree early morning temperatures at the time. Then, the next weekend I wiped the lower IMT valve black plastic base where it bolts into the intake manifold with a clean white paper napkin (as I learned to do from Rick here) and voila, there was the telltale sign of fresh oil on the napkin. Our factory O-rings were officially leaking now, and I had caught the leak before it had a chance to manifest itself down below on the heat shields. So I bought two of the new green-colored IMT O-rings, changed them out, and all is now well again as the car approaches 42,000 miles....

Every S-Type 3.0 built with the original yellow-colored factory IMT O-rings should have these things changed out with the new green ones immediately. Leaking O-rings can cause a number of different problems and it is foolish to leave them in place. It is not a question of if they will fail, but when they will fail. It would help all S-Type 3.0 owners if Jaguar could confirm on what VIN number they started building the S-Type 3.0 with the new-style green-colored O-rings, but I don't think they know. My guess is that they made the changeover sometime during the production run of the 2007 model year. So probably only the 2008 model year is unaffected by this chronic problem....

The good news is that for something that causes so many issues with these engines, it is a very cheap fix if you can do it yourself. Less than five bucks buys you both O-rings at your Jaguar parts department. So don't hesitate. Read the threads on how to do this, get your two new green-colored O-rings in hand, and go for it....

 

Any air leak means the PCM (engine computer) will be adding fuel but it's just doing its best as it doesn't KNOW there's a leak. Bad mpg no surprise.
IMT, probably. You could have another air leak as well but IMT are cheap and fairly easy so do them and watch mpg and idling after.

 

Thank you guys
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Lambo Tech