1990 XJS Catalytic Converters

[matt1990XJS]

I have a 1990 XJS V12 and recently had my rear crankshaft sensor replaced and then it burned out again. I was told by a mechanic that the catalytic converters were clogged and getting red hot causing the sensor/wires to burn up. Rather than replace the catalytic converters at great expense, can you just remove them and replace with exhaust pipe? I really don't care about getting it inspected but don't want to hurt the car. any feedback would be great. Thanks

 

[jessebogan]

Yes, you can do it, but the govt says you cannot. Removing cats can result in a large fine. If you look on the 'net, there are people that sell the european down pipes. Make sure that they have provision for the oxygen sensors. But really, you should find the cause of the problem, and fix it. Most unusual for the cats to get hot enough to melt the crank sensor. Perhaps the cap and rotor need attention, or you have a coil failing. Raw fuel dumped into a cat will cause a meltdown every time. Marelli caps go bad, but more often, the rotors burn through. If you look, you can still find genuine Marelli parts, which are expensive, but are also worlds better than the aftermarket ones.

 

[Deleted member 8987]

Vacuum leaks, EGR valve bad, seen those cause a red glow under the car.


I recall on Fords, with the honeycomb catalyst, some folks removed the cat, took a pipe and went in one end and broke all the bits out.
Then re-bolted the cat in place.

Passed visual every time, and ya know, the emission readings still were withing spec.

Go figure.

 

[Exotexs]

just order the Euro pipes, (cat-less pipes as they use in Europe). The XJ-6 has a Y pipe with a cat, and then it has the "down-cat" just below the exhaust manifolds. I don't know about the XJ-S but it should be somewhat similar.

another option is to open the down cat and clear all the garbage in there, re-weld it, pressure test it, repaint it, reinstall it empty ) Fools everybody or like TOC says, "passes visual".

If you do the Euro pipe and want to preserve the O2 Sensor (and you should like Jesse said), you'll need to cut out the "bong" from the old cat and weld it to the Euro down pipe. No O2 Sensor in Europe either.

you can order the Euro pipe(s) here:

https://www.motorcarsltd.com

I did a catless Euro Y pipe in my '84 XJ-6 and did the "clean-the-down-cat" job, the engine breathes better and runs a lot better, more power.

the irony is that the car passes inspections, go figure!

Ex

 

[PhilW]

Ah, yes. hammering out the ceramic in the cats. There's a lot of garages out there that have dirt outside the back door, worth it's weight in platinum.

Phil.

 

[Exotexs]

ceramic? at least in my '84 what I found in there, was a meshfull of carbonized carbon "honeycombs", easily removed. It was sort of like an Aquarium Carbon Filter. No ceramic. The stuff is toxic, so best to wear a breathing mask, proper gloves, Hey Men.

Ex