So the 1964 Daimler had issues with the fuels lines and gas tank. Cleaned and purged both with rather positive results.

( https://www.jaguarforums.com/forum/m...ilters-148645/)

( https://www.jaguarforums.com/forum/m...estion-147278/)

So last night I put two gallons of gasoline in the tank, turned the key to start the electric fuel pump, and waited for the gas to flow from the back to the front. Nothing. I removed a fuel line and began sucking to help prime the lines and fuel pump. And then the fuel flowed out! Why was priming needed? I don't know... ( Safety hint: Always wear protective goggles when doing this procedure. NOTHING is worth compromising your eye sight! )

There were leaks in the sight bowl area and the front left carburetor. And not just little drops.... gushes of fuel! So I turned off the ignition and removed the sight bowl from the mounts. Removed and tightened the intake and outtake threads, and then readjusted the rubber seal inside the sight bowl. Reattached and tested: no leaks!

But the carburetor was still vented gasoline. I don't know what to do about this yet, so I'm requesting assistance before proceeding.

I wasn't sure exactly where the leak was originating from... and I'm still not sure. It looked like the bottom of the carburetor, so I took off the four mounting bolts from the intake housing and the cotter pin from the accelerator armature. I then tilted the carburetor and saw fuel leaking copiously from the an interior area where the carbuerator faces the engine mount ( Still have not seen the actual location of the leak).

So before I take of the this leaking carburetor and start dismantling it to address the leak -- something I don't want to do if at all possible -- any ideas as to what is the problem and best practices of fixing?

Might it be a dried up gasket since the engine hasn't continually been operational for some time? Or maybe a loose screw?

If the carburetor MUST be removed, what are the best practices for dismantling and addressing this issue? I want to avoid making problems, especially with a carburetor! ( Please detail in baby steps for this neophyte. )

TIA

 

Basically a leaky carburetor means it's time for a rebuild.
That leak is typical in that area where the choke linkage is.
There is a seal around the main jet that leaks.
Some have diaphragms sealing this area off, I don't know which is correct on this model of SU carb.

There should be a small aluminum plate that is held in place with the banjo fitting bolt on the breather tube of one of the float bowls.

The plate has a number stamped on it _ that is the model number of the carb.

Parts for AUD 180 for Daimler Saloon V8 2548 cc - SU Carburetters - SU Carburetters

The diaphragm in part #4 can fail and cause the leak you're having.

Have you rebuilt a carburetor before ?

 

As was noted in the original posting, The SUD carburetor was leaking from the bottom. I asked around at local parts stores, and no one had any idea. One place got me a rebuild kit for $14 , but before I opened the packet, more inquiries were made.

I went to a local carburetor repair shoppe and actually brought in the entire SUD unit. I was told the entire SUD needed to be rebuilt at $650, and the critical part was a special calipre guide the ensure the needle in the interior was centered. I was told to replace the SUD with a Weber carbureator.

Then something interesting happened.

I was walking through a home show with an interior wood piece from the car. ( I'll post that story later...) . As I was walking down the aisles, a guy hawking dust mops called out to me, "Hey! That's a piece from a Jag!" He saw the sample piece I brought in and knew it by sight from a distance!
When I asked how he knew that, the hawker said, " I know everything..." And he then went on to describe the piece, the wood, the way to restore it, and other details.

I then asked about the leaking SUD. He said it was no big deal. Just a gasket. He had replaced the stock carburetor on his Harley with a Jag SUD because the SUD is a SUPERIOUR carburetor due in part to the Vernelli tube design. ( This is the exact opposite advice of what I was told to do and replace with a Weber ).

To be sure, the next day I brought the SUD to him to see live and in person. The Hawker said it was similar to the type he swapped onto his Harley. He then detailed how to remove the screws, the springs, and what he believed to be the cracked gasket piece. When I asked about the special calipre gauge, the Hawker said just be careful and go slow.... work in a box so that if a spring or part does come out, it doesn't go missing.

So with fear and trepidation of having a $650 rebuild, I did EXACTLY what the Hawker told me to do: worked in a box, removed the screws, gently pulled off the bottom, and the centering spring came out.... my big fear!

And there it was, as The Hawker said! A cracked gasket/diaphragm(?)!
I gently dislodged the piece from its four mooring posts and the position needle, and the reason for the leaking was now apparent: It was old and cracked! ( See pics)

I then went to the local parts place with the piece in hand. I got my usual lecture of how I don't spend enough money to make my purchases worth the vendors time and how most of the customers make BIG dollar purchases ( doing what I can where I can with what I got, friends! ), and I bought the replace piece.

It was flexible and not cracked, unlike its predecessor piece. ( See next pics ). Before I put it back on, I cleaned out the bottom of the SUD, as it had some scale build-up. ( Last pics )

I placed the needle into the center, positioned the guides, put the spring into position, and reattached the screws with an even rotation. And I prayed.

The SUD was then rebolted into place, and new cotter pins were placed into the throttle linkage.

The test: the engine turned over and ran WITHOUT any leaking!
(I did tighten all the hose connections and replaced all the hose clamps just to be safe. )

One less issue, one more step to a completed project!
Thank you, Mr. Mop Hawker!
( And I'll tell him so and give him a thank you gift next time the raod show is in town. )

Sidenote: I ***REALLY*** want to learn more about SUD carburators and particularlly the Vernelli Tube application it uses. I'm told the SUD --- like many Jaguar parts and systems --- was far ahead of its time and are actually far superior but misunderstood. Any links/guidance/thoughts on this is appreciated!

 

That is an awesome story. Thanks for sharing, and kudo's to the Mop gawker.

 

I think, if you google SU carburetor, or carburetter, you'll get plenty of info. That's what I did when I had a leaky SU carb. I totally rebuilt by carbs 3 times chasing the leaks. If it leaks again I think the issue might be the little washer at the bottom of my forward carb.

This is a good example of what you will find. And this guy even speaks specifically about the Venturi that you are talking about. The video production may not be the greatest but the info is good:

 

Exceptional! Thank you!

 

I have a PDF copy of Haynes Weber, Zenith and SU Carburetor Manual if you PM me I will upload it somewhere and send you a link.

 

Quite welcome

If you manage to procure a copy of the MK2 Service Manual (I downloaded a PDF - Search "jaguar mk 2 manual") there is an exploded diagram on Page C.14. I printed that diagram off and posted it in my work cubicle when I was having difficulty figuring it out.