Hi Guys,
So I've developed what sounds like a massive vacuum leak somewhere around the supercharger. Had been getting the occasional CEL with code P0193. Checked wiring and plug to fuel pressure sensor, reset the battery & it seemed to go away- Car was idling & performing fine. It then developed a really ropey idle & I could hear a loud vacuum leak coming from somewhere around the supercharger. As I was pulling off the vacuum line from the fuel sensor to the s/c it fell to bits so replaced that with some fuel line I had - no difference. Also checked the line running from the value cover to the elbow above the t/b & it seemed ok when trying to blow thru it looking for a leak. What else should I be checking? Any advice would be greatly appreciated!

 

It's most likely the SC duct seals . It's a relatively easy repair.

Early XKR's had what could be called a design flaw for the SC inlet duct seal assembly.When coming off throttle the rubber seals get sucked into the intake, creating a massive induction leak.

Purchase the later style kit that has grooves in the seal plates to hold the seals firmly in place, or get out your dremel and create your own.

 

Hi there. Thanks so much for this advice. Been looking at the JTIS. Could this be called the s/c outlet pipe? If so I can see instructions on how to do that.
Where would I purchase a gasket kit?

 

This is just one place of many that carry it. Use this just as a visual reference.
https://www.xk8-parts.com/2017/02/ja...s-upgrade-kit/

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My car had a later model seals already fitted. Leak sounded like coming from front of s/c near the inlet pipe. Seemed to get increased idle spraying cleaner in that area so bought new inlet pipe gasket. Fitted that, no change. So glad there wasn't a big hammer within arms reach! Car is seriously driving me nuts- things breaking faster than I can fix them. Love the car but pretty sure I spend more time underneath it than driving it...

 

I know how you feel, I've had planes that took less maintenance then my 01 XKR!

 

The updated seals are only half of the equation. The grooved plates are the key to trouble free sealing. So yours are the grooved variety?

 

The 4.2 I think always had the updated seal parts.

I would check the part and full load breather pipes / fittings / seals with the spray. They are that corrugated plastic and can crack.

There is the fitting that comes off the passenger side of the outlet pipe, little brass looking tube that connects to the fuel pressure regulator vacuum / pressure hose.

Check down the sides of the supercharger left and right, which should cover the intercooler seals and injector manifold seals. I hope for your sake it isn't these, what a PITA.

Around the throttle body and intake elbow.

And the bypass valve and the hoses that come off the back of the intercoolers.

 

I'II check & see if the plate is grooved but have to say the leak is very loud & sounds like it's coming from the other end of the blower - towards the snout. Sounds very localised to the front of the s/c although I can't seem to see anything...

 

Thanks for this, I'II look at these items. Have checked the corrugated line from t/b elbow to value cover & that seems ok. Also checked & replaced the line from the s/c to the fuel rail pressure sensor so know that's ok..
As mentioned above leak sounds very localised to the front of the s/c.
I assume there's a gasket at bottom of s/c between it & intake manifold & I'm wondering if it could be that? Looks like I may have to bite the bullet & get it to the mechanics for a smoke test. It will barely idle the way it is so gonna be a challenge to even get it there.
If anybody thinks of anything else to check please do let me know - really can't afford to keep paying 'experts' to fix it!

 

By normal car standards the supercharger is installed upside down. The only gaskets are at the rear for the intake elbow and on top for the outlet pipe, which you already changed.

The air flow comes out the top of the supercharger, moves toward the rear of the car, makes a U turn into the L & R intercooler plenums, then down the individual runners to the fuel injector manifold and into the cylinder.

There are 2 gaskets on the intake runners, one for the intercooler to the injector manifold and the other between the injector manifold and the cylinder head. You can spray a little cleaner down either side of the supercharger to check these. A leak in those gaskets is kind of a pain as the supercharger needs to come out to gain access.

Listening to the idle works but a more sensitive way is to watch the STFT with an OBD meter while you are checking joints with the cleaner.

You say the car will barely idle, but if you rev it up does it straiten out and the fuel trims look more normal? A small vacuum leak will get dwarfed by the amount of air coming through the throttle and can be a way to check whether it is really a leak or something else like the MAF.

 

Jeff390.
On top of the S/C you will find a square cover (I call it the Hat) it has V8 on top....It is held down by (4) Bolts....each with a Rubber Washer under it. Also, there is a square Gasket under the Hat....All subject to alot of heat and pressure. My XKR has an extra large Lower S/C Pulley and a Small upper Pulley and creates up to 25 lbs. of Pressure....There is alot of heat and pressure in that area and the Washers tend to break up and allow pressure to bypass. If they are old and cracked they will leak all the time. If this is the problem, you will need to get several of the Rubber Washers and while you are at it a new Square Gasket that fits under the Hat.
Because of the pressure, I've had to do this several times...Also, the 2003 that I had did not have the Grooved connectors in the outlets and I had to replace them with the new type as they continued to blow-out or got sucked in.....

Billy Clyde in Houston

 

Thanks for the advice. Much appreciated. Will look at the injector gaskets. The running does clean up hugely under load/at revs. Car definitely still makes heaps of power so guessing it is a vacuum leak.

 

Thanks Billy. I replaced the square gasket and upon inspection I couldn't fault the old gasket. Bolt rubbers looked good too. Might be the grooved plate thing but sounded like it was coming from front of the s/c not the back...
sure is frustrating

 

Jeff,

Well, I'm glad it was not the "Hat" or those little rubber gaskets.....That has become a PAIN for me......If I really get on it several times or over a period of 2 or 3 weeks, the pressure that builds up will blow them out....and you can feel the loss of Power when they go! I guess I've put to much Pressure on that area of the S/C, as 25 or more lbs. of Boost is a bunch.....

The only other thing I can think of would be the little Rubber Pressure hose that runs out to the side......I have my Pressure Gauge hooked-up or I should say "Tee'ed" off of it....It can, after a while, starts slipping off, unless you put a tie-tie on it....I think this hose goes to the pressure sensor on the end of the fuel-rail ...Those are the most logical places....

Billy Clyde