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Vacuum leak found, whats the part?

18K views 13 replies 6 participants last post by  RdSnake 
#1 ·
After watching shrodingers box's "fuel trim" videos, I diagnosed a vacuum leak. Next I made a smoke tester.
Tableware Drinkware


Testing proved useful but not great news. I was hoping for some super easy hose I could trim shorter or reseal or easily replace. Please have a look at the video and help me identify the hose/part the hose is plugged into. I can't tell if it's the hose or the connection to engine that's leaking. I think it's connected to the supercharger?
 

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#3 ·
That is where the servo vacuum line goes into the block at the back. Its just a push in fit on mine, pulls straight up out of the block. Check its pushed in all the way, looks like it is, or you might be able to pull it out and wrap a bit of PTFE round it just below the stop and put it back in.

I do also have a 4mm(?) vacuum take off back there that my LPG regulator is connected to so worth checking that too, might have a bung on it if nothings connected. Its just above and back a bit where that pipe goes into the block.

Cheers
Stot
 
#6 ·
well, win some lose some.

I took the plenum off to get a better look but I still couldnt tell what exactly was leaking until I sprayed some soapy water and then it was clear as day, the push connector was leaking. I pulled the hose out and cleaned up the surfaces, even put some silicone grease on the hose, but I could still see bubbles. this could have been because the connector is designed to work in vacuum not pressure?

Auto part Engine Fuel line Automotive engine part Pipe


Now for the lose time... I thought "ok, the little rubber oring is worn out and I can replace that, just gotta pull it out to find a match..." turns out its a hard plastic ring? it's also very brittle. I tried pulling it out and it broke a chunk out. most of it is out, still a small grain of rice sized piece of black plastic in the intake.
Cobalt blue Tile Electric blue Pattern Metal

so now the question is, can I replace this plastic piece with a rubber oring. even if I found another plastic seal, it could break trying to insert it. but I also have to wonder how they got the plastic bit in there in the first place.

Any pointers on parts or what I should do is appreciated. also, do I need to worry about that tiny piece of plastic?
 
#10 ·
.. I tried pulling it out and it broke a chunk out. most of it is out, still a small grain of rice sized piece of black plastic in the intake.
Looking at your picture you have the clip on the right of the shop image (C2S15816) inserted into the inlet, so is the o-ring at the bottom of this normally assuming if so the brass insert pushes into the port?

Cheers
Stot
 
#7 ·
so a quick search found me this:
https://www.motorcarsltd.com/search.php?mode=search&page=1&keep_https=yes
Product Auto part Rim Wheel Knockout punch

"Pt# C2S15816 is the little collet on the tube that runs from the booster to the intake on the XType, Stype, XJ, V6 and XF the failure is usually an o-ring that is fitted down inside that collet. Jaguar Factory DOES NOT offer the o-ring seperately. We however now stock the o-ring separately Pt# C2S15816.ORING."

https://www.motorcarsltd.com/c2s15816.oring.html

looks like a rubber o-ring to me!. maybe mine just got brittle?

I'm going out to find an o-ring!
 
#8 ·
I couldnt find a perfect O-ring, they were all too big in ID or too thin. The specialized shops are not open on the weekends here so I have some more places to check out this week.

I used a couple imperfect o-rings to get the truck running, but there is still a small leak. Does anyone know if these plastic rings are replaceable?
 
#11 ·
JDT, it looks to be press fit. I don't know how i'd get the whole brass connector out.

Stot, the plastic clip would push the oring down when inserted, so the oring sits below the plastic clip.

I finally found a thick enough o-ring at a specialty air/hose store. The hose is 9mm OD, the oring is probably 8mm ID and double the thickness of any hardware store O-ring. its also a hightemp variant. it fits inside the brass connector well and was a TIGHT fit getting that hose inserted. very satisfying when it pushed in with the help of some silicone grease...

I confirmed with the smoke tester that it doesnt leak. unfortunately, this hasn't solved my lean problem. I'm still around 13% at idle on the LTFTs, which is better than the 18% I had seen before but it's still high?. I didnt see any other leaks. Except, in one test when I had the plenum and airbox/resonance thingy off, I used the hose that comes off the air box and goes into the right side of the engine as my smoke port. I had smoke coming out from around the oil filler. not the cap, but where the fill tube goes into the engine... I guess it makes sense this leak only showed now, since before I was injecting smoke above the pistons and this time I was pumping it in below.

I still have an "EVAP leak" to investigate, which was throwing a fuel cap leak code sometimes. If I pump smoke into the vacuum system, like I have been, would it make it all the way to the fuel filler cap?
 
#12 ·
So I am heading down exactly the same path with my 2006 SC Full size. LTFT showing lean, did a smoke test, smoke pouring out of the connector wondered if it was a vacuum vs air pressure thing. Looks like I am going out looking for o-rings. Thanks for the post. I did notice on the SC that there might be another similar connector on the supercharger housing that was possibly leaking. Cannot believe there is not a better solution
 
#13 ·
Just a small note:
That push connect fitting on the brake booster is in very precarious location and often damaged either by tooling up front or even the self-tensioning water pump belt. A crack or other damage of the plastic fitting is often accompanied by random smoke clouds of unknown cause or symptom. That brake booster vacuum line and fitting, if leaking, can cause oil to be sucked into the intake.
 
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