After changing the ECU and gearbox of my jaguar xjs v12 twr and following your advice, the car is now working properly (Thank you all very much).
However, I have a big exhaust leak that I can’t figure out where it’s coming from, so I’ve disassembled the manifold on one side (the easier side) and I don’t see any carbon build up on the gaskets or signs of it leaking from there.
However, and I don’t know why my manifolds with the exhaust are not connected with the typical union with screws, but the scale goes inside the manifold. I don’t know why I haven’t found any pictures of this system on the internet, I don’t know if it wasn’t original, but I think the exhaust leak comes from there.
Is it possible that I have it badly mounted and needed a clamp to make pressure on both tubes so that they do not escape? I think I must have the problem there and not in the joints of the manifolds…
Hi Josep-
This is not a “normal” XJS setup, which uses two cast iron exhaust manifolds, you can kind of see in this picture:
I am assuming your setup is unique to TWR. Having said that, I think I would treat it like any other car with exhaust headers. Good gaskets, good nuts on the exhaust port studs (I used Nord-lock washers on mine) and definitely some sort of clamp at the union you mention. I have seen slip-fit like this in other applications, and most of the time they leak. If you have any room at all, there are a lot of clamp options:
Perhaps someone who actually has some hands-on TWR XJS experience will chime in.
Thanks for the information.
So the manifolds are different maybe because it is a Jaguar TWR.
The point is that I have an air leak, which is audible at the top of the engine, in the V of the engine.
I bought the exhaust manifold gaskets and replaced them on the side that sounded the loudest, put washers between the manifold and the exhaust but the car is still leaking.
I still have to change the other side but it doesn’t seem to be coming from there. Does anyone know where I can have a connection air leak if it is not in the exhaust? It is very strange as it sounds in the engine center.
The air injection system has small drilled passages directly to the exhaust ports; it could be leaking there. The air injection manifolds fit into the intake manifold near the cylinder head, which would account for the noise being in the vee area. If the air injection is removed (frequently), those drillings need to be blocked off. There are details in the Kirby Palm book….perhaps one of the block off plugs are leaking?
Also have had loose or cross threaded spark plugs create an exhaust leak like sound.
Yes, I removed my air pipes and filled the holes thru intake manifold. I didn’t do a very good job, and was getting little pop noises from Vee area. Sounds like a very loud clicking noise. Perhaps this is what’s going on?
It’s only a minor exhaust leak, so not detrimental, but it is annoying.
Thanks for your answer.
You mean the intake gaskets? it seems that the intake should not have this compression, no?
I have checked spark plugs but they are tight, I also thought it might be the spark plugs but it’s not.
Thanks for your answer.
Ok, I understand that you are referring to the joints between the intake manifold and the cylinder head, although it seems that a priori there should be no exhaust pressure there.
It is a bit annoying, but it sounds quite a lot so it’s possible that I won’t pass the itv and that’s why I want to fix it before I go.
(Thank you all very much).
