Hello, I'm removing my cats to check them for damage. All safe and secure chocked, on steel wheel stands and double-checked with stands.

I have the right hand downpipe disconnected from the exhaust manifold. How do I actually disconnect a joint somewhere to be able to remove them? I have the bracket off the trans. I have all the clamps loose on the cat and the first silencer. What now?

 

You should have, around the front area, just behind the bend, a joint. 3 screws around a triangular bracket... Undo that and the downpipe will just pop off...

 

There were a few different 1st joints. Mine was a slip joint off the downpipe and PITA to separate. If yours is a slip joint lots of penetrating oil in the pipe if its rusted together.

Mine was over tightened which narrowed the pipe and locked them together I ended up having to cut it open to get it apart.

 

I don't know how you're supposed to do it, but I was able to push on the rear muffler with my foot and separate the rear cat. I think I should have done this first as removing the cat from the downpipe with the downpipe disconnected was not easy.

Good news though! My cats were melted! This was not all a waste of time and effort. Part of the metal foil insert had fallen down on the cat as well. Also melted I suppose.

 

Mine was a slip joint as well. Not crushed or rusted though. Channel locks ahead of joint and a BFH separated it.

EDIT: Update

Right side cats "repaired" and right side reassembled. Left side ( driver's side here. ) is proving more challenging. At least I know the sequence now.

What's the max u-joints you can use on a ratchet at once?

 

So clearly both cats were clogged with Molten ceramic. Both "repaired" and reassembled. Cranked her and she fired right up! Purred for 10 seconds and then shut down. Since I was standing there with the hood up I could hear a cylinder decompress into the intake as she stopped running. Still backed up.

Can the mufflers become clogged? I didn't see signs of lost material from the cats.

What's the next step?

 

It's going to sound like a WW2 fighter but try starting up with just the downpipes.

 

This was an option. I pulled the drivers side forward muffler. Rusty as hell inside shook out some bits. But it wasn't clogged. Neither is the rear on that side. Ran out of time before I could pull the right hand side.

I will check the right, but I'm thinking that's this is another Jaguar prank. Find the broken bit, fix it, no change. Seems common here. Next up after mufflers is new fuel filter, swap pump, jump out right FPR and shake a dead chicken at it.

More educated suggestions gratefully accepted.

 

Don't get disheartened - keep at it. Once you get it running right you will have the best touring vehicle around.

Work methodically. When I'm fault finding I like to disconnect as much as possible, then systematically connect until I see a change.

Baxtor has a good suggestion.

 

Thanks Warrjon, I'm not disheartened, just being realistic. Thirty year old car, minimal maintainance over its lifetime. Failures here are often more than one cause. She can handle a lot of issues and still run. It's when two or more join forces that they win. And fixing problems in one area can strain other systems that are used to the way it was. Once I was getting real power from the v12 the mounts in the rear end started complaining for example.

I'll keep wrenching and get her running again! And I'll open the exhaust up at the end of the second cats to take the mufflers out of the equation. I'd rather avoid dropping those down pipes again if possible! My cats are definately not a part of the problem any more.

 

Sounded pretty awesome! Ran well and idled nicely for twenty seconds. Then if died out.

So not the exhaust.

What's my best direction for the next step?

 

When she has died, check for spark while a helper cranks. If you have a spark it is probably fuel. Start at the tank and go through the system, nothing else for it.


Greg

 

Yes, I'm thinking it's fuel starvation. Pressure if fine at 30psi. Fuel pressure remains consistent throughout running and when she cuts off.

Return line is clear and undamaged. Supply line clear and undamaged. Fuel tank is spotless inside with no particulates or contaminants. Fuel filter is clear and free flowing. Dumping it out its inlet shows not a single speck of rust or other particles.

So I'm up to the engine bay. FPRs and injectors.

 

As Greg said, it could be fuel system,. Change all you mentioned, pump, fuel filter etc. also check he sump and change the filter/sock in that. you may also want to disconnect the fuel line under the hood for the intake and blow out the line from the back. when I did mine that's what I did and you will be surprised by the stuff that come out.

How are your injectors, before changing mine I had 4 totally block and 2 partial block. not even sure how it ran

 

I forgot to mention swapping fuel pumps and the swirl tank ( sump ) checked out clean and the filter on the pump line in it is clear and in place.

I don't see any harm that could come from blowing out the lines and , while they are flowing well there could be some buildup or restriction internally that I can't detect. Will do.

Last time I pulled the fuel rail all my injectors were firing and had reasonably good patterns. But I've never checked the injectors inlet screens. I'm suspicious that something may be there causing a buildup of restriction after flow begins.

Once she cut off yesterday she would not restart. I suspect that she will fire up tonight and the shut down promptly again. But that's speculation based on the pattern I'm seeing.

 

Have you checked/renewed the gravity pipe from the main tank to the sump tank. This can collapse inside (even though it looks fine outside) and block once the fuel pump gets going. Then after a bit it recovers and all is well. Just a thought. Anyway, if you do a spark check next time the engine stops, you will know for sure if it is fuel. My guess is it is NOT the injectors, as if they are getting blocked I cannot see why they would unblock after a wait. But, it is worth bypassing the A bank FPR to eliminate that from the equation.
Greg

 

Will do on that A bank FPR. I have NOT checked that fuel line. I'll replace it.

I am getting spark after it shuts down. I checked and swapped to a known good cool as well just to see if I had a bad new one.

I really don't have a clue and my injector screens clogging then clearing sounds questionable even to me but I have had a similar issue on carbureted cars where they would run for a bit then sediment would clog the filter sitting would allow it to settle and clear partial for the car to start again. But Jessie has a clean tank and no known fuel contamination at all.

Clutching at possible straws. Missing my beautiful ride, tooling around on the 78 f150 is a big change.

 

Found it.

Loose + on secondary coil. Kicking myself, but those cats needed help so not a waste of time.

Now to put the exhaust back on her.

 

Nope. Ran 5 minutes just beautifully and shut off.

In case anyone's interested, here's what she sounded like without the center or rear muffler, but with downpipes, cat boxes, and the center pipes in place.

[Jaguar XJS V12 Exhaust - No mufflers](https://clyp.it/p5h0ce2y)

And muffled.

[Jaguar XJS V12 Exhaust - With mufflers](https://clyp.it/dyyjnjgz)