I have an oil leak at the back of the engine, UK drivers side, which I've wiped off but it slowly reappears. It could be from the IMT rings or it could be from the rocker cover gasket, hard to tell. It then drips onto the exhaust shield.

It isn't a real problem yet, but if it's the IMT rings that are leaking what issues is that likely to cause? A vacuum leak? What do the IMT valves do?

 

This is my understanding of it

The intake manifold tuning (IMT) valve system uses variable air induction tuning in order to achieve maximum performance and efficiency over the entire operating range of the engine. The characteristic torque curve of a normally aspirated engine depends mainly on how the engines average pressure changes over the engine speed range. The average pressure is proportional to the volume of the air mass present in the cylinder when the inlet valve is closed. The design of the inlet system determines how large an air mass can be drawn into a cylinder at a given engine speed. An IMT valve is used to change the intake manifold plenum configuration. When the IMT valve is open, the intake manifold is configured to one large plenum. When the IMT valve is closed, the intake manifold is configured to 2 smaller plenums. The 2 intake manifold plenum sizes result in different torque curves, which improves performance at low and high engine speeds. During low speed, high load conditions the IMT valve is closed creating a longer runner path inside the plenum, which increases torque. During higher engine speeds and loads, the IMT valve opens creating a shorter runner path inside the plenum, which increases horsepower.


bascialy depending on engine RPM it can make the intake be just 1 large intake where air can go to both banks of teh engine at the same time or the valve closes and basicaly puts a divider down the middle essentialy making 2 smaller intakes 1 for each bank which makes more power.

If I'm wrong I'm sure someone will point it out

 

Thanks for that.

Seems to be similar to the DISA valve on a BMW, which was also troublesome regards it's O ring.

An oil leak from the IMT means that the vacuum is not as it should be I guess, hence the need to replace the O rings, rather than the because of the fact that a small amount of oil is coming out.

For a couple of quid and a bit of DIY I could replace them, seems easy enough. It could help me get more than 23mpg.....

 

Don't know if its needed or not, but just in case, these may help.....


video on how to replace upper & lower gaskets on a xtype

http://redirectingat.com/?id=42X198&...m/web/jfenley/


EDIT - why was I thinking X type??

Best

Jim

 

Tisk Tisk gentlemen, you should have checked out the "How To" section:

https://www.jaguarforums.com/forum/s...ck-pics-49214/

https://www.jaguarforums.com/forum/s...ics-faq-32135/

 

It's a bit more of a scutter on the S as they are located at the bulkhead.

You are right that the potential vacuum leak is the main problem with a leaking seal, the new seals are modified with sealant as part of the O ring. Mine were changed by the dealer in early 2008 and I had the manifold off recently an d there was no sign of any leaks.

 

It was as a direct result of reading these that prompted me to pen my post in the first place!