I would seriously take it to a reputable exhaust shop. They'll have all the parts you need. Just shipping the replacement parts might kill your budget?

JDHT will have the part numbers you need.

 

Thanks, I have booked her in for a visit to a repair place next week. I've ordered a used downpipe to save on parts costs at the shop, the front gaskets are cheap and easy to find as they are used on both the slip joint and olive joint downpipes, it's just the rear seal and clamp for the spherical joint I'm struggling to nail down. They seem very expensive for what they are and it's hard to find them. I'm tempted to leave that out, worst case scenario the shop has to reuse what's existing at the rear, but I can access those to replace them myself so I'm not too worried.

 

Thanks for the update, the exhaust shop will make it work. Let us know how it goes, and what the shop can and, more importantly, cannot do for you.

THanks.

 

Hi all, late update. Finally took it to the shop today, turns out the part I was sent is a foot or so too short despite being sold as an X300 downpipe suitable for a 4.0. Good old eBay! Perhaps it's from an XJ40? I'll attach photos later.

Anyway, I'll have to order another downpipe, a longer one, and with the olive/spherical joint. Does anyone know the part number for this specific downpipe?

There don't seem to be any olive types for sale, besides new ones on a catalytic converter supply website and SNG Barratt, but I'm not sure I'd trust aftermarket to fit. Plus, a lot more expensive with the shop's labour costs added also. I might try doing it myself after getting the estimated quote for labour! Does anyone here (UK) have a used olive-type one lying around?

If I can't find an olive one, how hard is it to convert to the other type? New downpipe, new cat section, and new seals? Or is it more in depth? If the two types are entirely interchangable besides the joint between downpipe and cats, I'd be tempted to swap and just buy both a new downpipe and new cats as used ones of the non-olive type are more readily available.

 

JDHT should have the part numbers you need. I got the ones I needed for my exhaust from there.

 

The long wheel base model is 6 inches longer then the short wheel base model. So the pipe has to reflect that

Easy error / assumption

The short wheel base model is 36 inches on the rear side window on the exposed glass lower edge

Note the no need for fwd O2 sensors for British model

Search Genuine Exhaust System Parts For Jaguar Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic | Jaguar Land Rover Classic Parts

 

Here are the photos of what was sent to me vs what was on the eBay listing. As you can see, there’s a sizeable difference. I believe the one I received is for an XJ40, whereas the X300 has a much longer one. So I’ll be hunting for one of those on the internet now.


Here’s what I bought. Listed as for an X300, I asked the seller if he had any of these with the olive joint and he said he did.



And here’s what turned up in the post. About a foot shorter, but at least it has the olive!

I think the difference is too significant to just be a case of short vs long wheelbase, especially as my car has the standard wheelbase.

Hopefully I can get my money back on this bit. Might have to buy a new aftermarket one and hope for the best? I’ll start dousing the bolts with WD40 in preparation for attempting this myself. Does this look like a good option: https://www.cats2u.co.uk/jaguar/2737...e-bm70317.html

On a better note, at least the car is inexplicably running smoothly now besides sounding like a Sherman tank!

 

I've just had exactly the same symptoms and the exhaust blew in the mid (Y) section, the single pipe bit. Thought the hesitation + back firing at higher revs might be caused by:

• Stale fuel - first run after winter hibernation.
• Oil breather fumes. Done an oil change and level is at max instead of mid on the dip stick. Took 8½ litres.
• Reduced back pressure due to exhaust starting to fail.

Done a temporary repair, still got a slight blow but nothing to worry about at the moment. Not yet done road test, will be a gentle one.

Anyone done a de-cat Y section and still pass UK MOT? Emissions on most recent test were low, one before were high and passed. On that test the thermostats was stuck open and engine never got fully up to temp, so was running rich.

 

Interesting what you said are your suspected symptoms. My stumbling started after running very low on fuel, perhaps the watery dregs at the bottom? But after filling up it continued, so perhaps unrelated.

I also recently did an oil change, with the level to the maximum.

My manifolds are cracked and a recent long battle with a dead misfire might’ve clogged the rear cats with raw petrol, as the pop came just after the primary cat.

I might try a liberal application of wire, exhaust bandage, and exhaust putty to seal the hole up temporarily to see if the stumbling problem reappears before committing to a new exhaust section. Don’t want to fit a new one and then have it burst straight away again.

 

I've replaced the front cats twice only to have the rear cat blocked by the debris from the the disintegrating fronts. I've replaced coils, plugs, temp sensor, fuel regulator, injectors, filters, etc. Runs great before the cats disintegrate. Been sitting since the last cat replacement. I'm thinking evaporator system is the culprit. Gonna finish my XJC first as I know that'll run...

75 XJ6C, 95XJR6

 

Is that a rare X300 2 door ?

 

Nooooo Parker!!! The 2 door X300 is a convertible...

1996 Daimler Corsica
My X300 is a sedan...


95 XJR6

 

If I were a billionaire coach builder, a two door coupe X300 would be high on my list of projects. I wish they’d made one, an XJC for the modern age!

Shame about your cats, seems these ones don’t have nine lives.

 

Before I tackle this job, does anyone have any tips on how to get the Jag raised higher on standard jackstands and a floor jack? When I changed the oil, it was a struggle to get under it. I imagine getting access to the manifold studs from below requires quite a lot more height.

 

I jack the front up from the side and put the wheels on short bits of 6x2, which gives enough room to jack from front on the cross member. Then axel stand on the side jack points.

 

Good idea, I might make some brick platforms for the front wheels. I was thinking about putting a thick bit of wood on the jack puck to get some more height out of it too.

 

Avoid bricks, timber gives more warning when it fails.

 

Update! Managed to get the car high enough to get under it comfortably. Comfortably may be a stretch, as my entire body aches and there's quite a lot of blood on the driveway now.

Using a 400mm extension I was able to undo three bolts connecting the downpipe to the manifolds. Two were 15mm, one was a 14mm, strangely. The only one left is the inboard rear, the one that you can't get at from below. This one is tricky to get a good grip on with a spanner. I managed to get good purchase once and it seemed to break loose with a bit of percussive assistance from a hammer, but from then on I couldn't repeat it and get a good grip again, so I've probably rounded the head off.

To circumvent this possibly rounded bolt head, I thought I'd remove the manifolds and try to lift the whole lot out as one unit. All the manifold bolts came undone nicely, to my surpise, and I was able to separate the manifolds from their studs with the downpipe still attached by carefully manoeuvering the steering column out of the way. One thing I've noticed with this car compared to my other car, a '90 MX5, is that the quality of the bolts is much better. Far fewer of them are rusted to buggery. I also managed to get the olive joint clamp undone with two 10mm spanners, not having to slice the thing off as many have suggested. So far so good then.

I wasn't able to lift the manifolds and the downpipes out as a single unit, they're sticking somewhere. Perhaps the O2 sensor wires? Perhaps the sterring column? Perhaps the walls of the engine bay? Will have another look in better light soon.

So my question is; is it possible to take the manifolds and the downpipe out as a single unit, or must they be separated? Also, where are the connectors for the two O2 sensors? I assume it's easier to unplug them from the car rather than unscrew them from the exhaust?

All in all, a pretty productive day of Jag fiddling after a day in the office, I've earned a couple of pints. Only one bolt got the better of me, which is far better than I was expecting. Glad the garage gave in so I don't have to pay them to do it.

 

Toby, I took mine out that way. Although mine is a North American spec car. I'm not sure what difference that would make although I do have 4 oxygen sensors. My project started as simply changing the aforementioned sensors but quickly turned into removing the manifolds and cats for crack and thread repairs. Half of my downpipe bolts broke off. Of course the slip joint was welded at some point. I'll do a post soon with lots of photos of the entire process of repairing the manifolds. Everything is done now and ready to put back on the car. I just need to manufacture some time.

 

Hi all. So I managed to get both O2 sensors out from the pipe luckily, I decided that was easier than finding the wires and unplugging them wherever they end up. With the manifolds pulled off their studs, I was also able to get at the last bolt holding the downpipe on, the rear inboard one. As it was severely rounded, I converted it into a 14mm by thwacking a smaller spanner onto it with a large hammer. With this off, finally, the manifolds separated from the downpipe, which promptly crashed down to the floor below. So we're halfway there.

My new downpipe section arrived from Cats2U, and on inspection it looks like it is the right part and should fit nicely, so that's also good. Cost around £210, so not painfully expensive. Of course, my manifolds are still cracked but they aren't making much noise, so that's a later repair. Hard to find replacements that aren't cracked.

I will try and reassemble everything over the next few days after work, then take her out for a tentative test drive. Hopefully, the stumbling does not reappear and it returns to its smooth running condition. I suspect the stumbling may reoccur, which would suggest a blockage in the rear cats if it ran well while air could escape in front of the cats. As long as it doesn't crack the brand new exhaust, I'll be happy.