When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I’ve got a leak between the front most exhaust manifold and the down pipe of my ‘94 XJS (4.0 AJ16). When I had a go at removing the nuts from the studs, the first one I removed was actually a bolt (there was no stud, and it wasn’t a nut corroded onto a stud, it was a bolt).
my plan is to buy a couple of olives (I think they might be called donuts in the US), drop the down pipe, replace both olives, and also replace the bolt with a stud and nut.
Is that a reasonable plan? Any ideas or tips to make it easier? What do you do if the stud comes with the nut?
Still learning, so any help appreciated, especially if there’s an easier way?
Jaguar use a crushable 'olive' for the manifold to downpipe join. The OEM ones are very hard to find now, but aftermarket ones are available. The aftermarket ones work, but periodically for a few times after fitting need tightening, which the OEM ones usually do not.
I wouldn't want to mislead you, and I'd hate to potentially disagree with Greg! But, I don't remember if there were any oilves on the AJ16 manifold to downpipe connection?
The reason I'm suggesting that is I worked on mine some years ago when I had the typical cracked manifold and the common split weld at the end of the downpipe. The attached photos show my downpipe and new manifold ready for reinstall after the downpipe had been welded. And it LOOKS as if it's a straight join between them with a flanged top on the downpipe. I don't THINK that's an Olive in situ?
If so, you may be able to disconnect the join, use some joint compound and reinstall. If you do split the join, be VERY careful not to put strain on the bottom of the downpipe. That weld at the end of the collector pipe (hidden by the end of the heatshield) is a fairly crude affair and you don't want to crack it. (It will do it on its own one day anyway!)
Thanks all, I’ll try tightening (after replacing the bolt with a stud and nut) then off that doesn’t work, carefully drop the down pipe, and throw new olives in.
Unfortunately it will have to wait until I can get the parts delivered, but I’ll let you know how I go.
OK, removed the bolt (which had stretched and deformed), re-tapped the thread (very very carefully), put in a new stud and nut, tightened up, leak gone.
However…. I noticed a few things:
1) There are four sensors coming out of the down pipe/ cat, two long cylinders that are connected up correctly, they run into the engine bay and look in good condition. But there are two shorter sensors (?) further forward, that look like they used to be connected with some very stiff wire, but no longer are. Anyone know what they are, and if it’s easy to wire them back up?
2) There’s another leak, at the connection between the down pipe and the horizontal exhaust pipe. It has a clamp (like a large hose clamp) on it, but when I tightened it up, it came to the limit of the clamp due to a hard piece of plastic between the clamp ends. Surely I’m doing something stupid here, as unless the olive inside is completely had it, tightening up the clamp should seal the leek?
There are 2 types of joint from the catalyst pipe to the single exhaust pipe - a slip joint, or a spherical joint (with olive). It's unclear exactly when each was fitted. If you look at the photos of my exhaust above. you'll see the slip joint type. There is no olive used in that joint. As you've mentioned a clamp, I'm guessing you've got the slip joint type? The bottom of that catalyst pipe is a fairly primitive affair with the two pipes coming into one. The join point weld of the 2-1 collector splits - hidden by the heatshield. You can see in my photo where we cut off the last few inches of the heatshield to be able to repair the weld. It may be that the last part of the pipe which goes into the slip joint has distorted giving you a problem. Or that the clamp has moved past the slip and now isn't able to tighten properly? I'll try and take a photo of mine tomorrow if that helps?
Yes, I must have the slip joint type, I’ve looked on the parts catalog, and the clamp I have looks the same as the part number for the the slip joint clamp.
So I guess the next question is, how to fix it?
I can try moving it and tightening it up again. I can’t help but feel that if it’s weight was supported there, there wouldn’t be an issue, as when I lift it slightly at the join, the leak gets less severe.
I guess, thinking about it, if you could give me an idea of where the clamp should go, that would be really helpful.
On my x305, there’s an olive at that junction, which sits in between two pipes, and the clamp spans the gap and clamps both pieces in place. To me, that makes sense, and is easy to see that it’s all in place.
On my XJS, your right, one pipe slips over the other, and the clamp is just aft of the end of the outer pipe. So you would have to clamp it up very tightly to create a decent seal unless the pipes were very close in diameter? Or should the clamp be positioned differently?
That’s really helpful thanks. I can also see that your clamp still has some adjustment left. I’ll have another look at mine, but I think it’s at the end of its adjustment. Perhaps it’s been subject to creep.
Glad to help. Also, looking at my pic, I see that I've lubricated both pipes when refitting. Is it perhaps that the downpipe collector pipe flares slightly towards its end thus enabling an optimal point where the clamp can be tightened to create a seal? If it really can't be sealed, perhaps you could put a stretching mandrel in and gently widen the downpipe a touch to create more of an interference fit?
Manifold - Exhaust down pipe leak
