Hi All.

Although this may get Doug, Greg and Grant rubbing there temples (I promise I'm not trying ta make ya crazzzzy), I have an exhaust and down pipe question/dilemma...

First,,, I need/want matching downpipes. It looks like I have two different downpipe/CAT systems on the L and R side.

I want to eliminate the CATS - all together if possible. I would prefer downpipes without CATS (not for HP or anything but due to exhaust restriction and the heat involved in how close the CATS come to everything in the super tight space in the tunnel area)... I will gut CATS if need be.

I think I DO need to maintain the 02 sensors - I think...??? I would like to.

This is happening not for nothing. Not exactly. Quick story:

Besides nonuniform downpiping,,, my welder guy, who welded in my LH floor, has a super steap ramp to get cars into and out of the garage. What he did to get from street level, up to garage level, is place a 1+ inch thick slab of solid steel as a ramp. Great! What happened was, when he was done welding in the the floor (I was standing there) he reversed out of the garage, the LH CAT bottomed and caught the lip of the 12x15ft steel slab, and stopped the car dead! Bending the LH downpipe forward, maybe 1, 1 1/2, to near 2 inches. Pulled the LH over axle pipe right off the hanger... That's my story and I'm sticking to it.

I have looked closely and although close,,, the bottom and first major kick/bend in the down pipe going rearward doesn't TOUCH anything (like the steering rack, gas return, subframe, mount or anything) in the area. But it DOES get close. Then, it hangs low as a result of the bending. So far, it's never hit ground but,,, it needs to go!

What v12 XJS year downpipes will FIT the 1990 XJS Convertible? So far I have kinda figured out (and I could be wrong) it could be the 88 to 91 downpipes...?

Guys,,, buying USED parts (for now),,, what would you do?

She's worth the trouble!

 

JJJ
Catless downpipes are easily available, but you do have to buy new ones or you are just wasting your money and time fitting them. O2 sensor bungs can be welded into them no bother. You do have to keep the sensors as I think (no actual experience) your ECU requires them to adjust the fueling. So you can kill two birds with one stone by doing the thing properly. Does your jurisdiction require cats though?
I am sure ebay will turn soemthing up:
https://www.ebay.co.uk/itm/Jaguar-v1...YAAOSwjLVdLDvp

 

Hi. Yes, law is that cars have CATS! But,,, it's super easy to get around... Sad but true.

But DAMN!!! Are you REALLY saying this downpipe would fit my car? If so, I'll buy it right now! And, like you said, have the bung welded in, and such...

Damn, thank you. Because I thought the whole problem so twisted, I've been reluctant to even post about it, lol

 

Not sure what side it is, you will have to check the part number, but it will fit, that is for sure. Keep looking on ebay.co.uk for the other side, you will find something for sure.

 

I'm blown away Greg, really! I had been looking - and struggling!

Hmm, I hate to ask, I'm here, you there (and seem to do this quite easily) would ya link the other, if you can find it? I am also looking for the RH resonator just before the over axle...

I, of course, will also be looking. But would appreciate the help.

Either way, thank you!

 

JJJ
CAC1974 is the RHS according to Jaguar Classic parts, CAC1975 the LHS
https://parts.jaguarlandroverclassic.../brand/jaguar/
The link i posted was the LHS, I think, so you need the RHS
try this:
https://www.ebay.co.uk/p/Jaguar-XJS-...974/1113764689

 

Thank you Greg...

So I'm bidding on that first one you sent (fingers crossed to win it!) and,,, the other two links you'd sent come up as items being "no longer available"...

But I have the parts numbers now and will keep on truckn... Part O the fun of it, I guess, lol

 

https://www.sngbarratt.com/us/#!/Eng...e-effa5692914d

Or the Luxury model:

https://simplyperformance.com/jaguar...steel-exhaust/

 

Can't afford it, Van ^^^^^^ that's what all of this is about,

Hi folks...

I WON the downpipe - $20bucks! Thank you SO MUCH, Greg!

So this is what I've learned...

My passenger side down pipe is a straight shot, no CATs and PO added a CAT after the olive connection... For me, this is good! The old welded in CAT will be removed on the RHside and a new intermediate pipe will go in its place. My RHside needs a new resonator,,, I have my eye on a stainless steel OEM Jag resonator on eBay. I'll get it. This is good, too!

Intermediate pipes are less than $30 bucks!

The new downpipe has no 02 sensor bung. Thanks to Greg, I now know that that is solve-able, easy! The resonator on the LH side is near new SSteel OEM Jag, and perfect over the axle all the way back. I will replace the intermediate pipe on the LH side side as well, and be done with it.

****QUESTION**** Is there anything I need to know when removing the bolts for my LH downpipe? Two bolts each!!! Days and days dousing it with WD40? MAPP torch?? I AM HORRIFIED at breaking bolts in the manifold... Real advise needed here!!!

Thanks all. Thanks Greg!

 

Sorry, saw your car and got lost in it's beauty didn't read the whole post about used parts.

WD40 is..meh, if you want to be sure then mix up 50/50 brake fluid and acetone and begin saturating the desired bolts. Be ware it will strip skin, paint, etc. Maybe wrap a cotton towel on and soak it.

 

Brake fluid/acetone, ATF/acetone, Aero Kroil, PB Blaster....they'll all work or at least help. Aero Kroil is my favorite, personally. Begin the soaking process days in advance and hope that whatever you use migrates into the threads.

However......

V12 owners get a built-in Mulligan when it comes to the exhaust manifold studs. Each manifold is drilled for four studs but only two are used. SO.....if you break a stud or studs you can just install two new studs in the unused holes and rotate the clamping flange 90º and, voilá, end of problem! Been there, done that. If you're on a timetable it might not be a bad idea to order a couple new studs ahead of time, just in case.

Cheers
DD

 

While that is certainly an advantage now Doug, it was a real pain way back when they actually used all four of those studs on each manifold. I have long memory of long hours spent getting at and unscrewing those nuts.

 

I hear ya.

I've had a set of non-cat downpipes for some time now. I'm working up the gumption to install them. The LH side in particular looks tricky-ish.

The cat converters hang low, and my car sits lower than standard....so the ground clearance is pretty tight. A few more big scrapes and the resulting damage may force my hand. I should probably bite the bullet and install the pipes more sooner than later

Cheers
DD

 

At home - I use sewing machine oil for the difficult studs - easy to apply (small spout - so it keeps the area clean) and is cheap.

At work (non vehicle related) - I use a product called Yield. Which is not cheap, a lot messier to use, but is very good

Cheers
Steve

 

JJJ
You may have to get under the car and use long extensions to get to them from below. Maybe your mate can let you use his lift (providing he does not bend the new one like the old!).
The nuts are imperial sizes (1/2, 9/16ths etc a/f sizes) or might even be Whitworth not metric and the exactly correct socket is a must, you do not want to round off a nut. As Doug said, I fully endorse a 50/50 mixture of ATF and acetone pint it on over about a week and the nuts will fall off!
The nuts are brass by the way, and longer than normal, and if you have to use new ones, use brass again. Good luck.

 

I wanted to change my subframe bushes: 6-shots in front and V-blocks in rear as they were seriously detoriated and I had a noise, that could be caused by to much subframe/engine movement.
It turned out I could not get proper access to loosen the LH V-block front bolt under the chassis rail, so I decided to drop the downpipes.
It now turned out I couldnt get access to one of the manifold nuts, so I decided to loosen/move the steering rack.
It then turned out I couldn't do that without dropping the sub frame, so I did that, and from there it was piece of cake to work on...
I then changed all bushes, stub axles and wheel bearings as well as cleaning and painting everything. Took a bit more effort and cost than I had expected, but it felt good afterwards...

 

JJJ
Further to my last note, you need four of these:
https://www.ebay.co.uk/itm/JAGUAR-DA...kAAOxyxU1Q5u8J
They go between the downpipe and the manifold, and crush into place as the nuts are tightened to seal the manfold/downpipe joint. If you can find genuine Jaguar ones (these claim to be) they are worth the money. Aftermarket ones need continuous tightening which is a royal pain.

 

Thank you Greg! Thank you all...

So, I did some dousing and waited some hours... I put a 14 or 15mm wrench (I just read the post about brass NUTS (LOL) and there being SAE sizes) and low and behold,,, at least the two outermost bolts turned quite easily... A really good thing!

I got the largest and outermost heat shield off and can see down in there. I believe I will be able to get under and get a tool on the inner two bolts. If they are as loving as the outer two, well, small miracles! Gotta hope for em.

For the rings, Greg,,, I'm only planning on doing one side. The down pipe on the other side has no CATs - I'm leaving it... I am intending on opening the olive connection below and I, or a shop, can fit a nice long stretch of intermediate pipe to the next section resonator... Is it 4,,, or two crush gaskets per side...???

Do exhaust shops stretch/flare pipe for olive connection type fittings?

Embarrassed by the mess,,, but I'll get there. Those outer visible bolts do turn!!!

 

Also, what do folks suggest if I open the downpipe on the driver's side and see that crazy honeycomb filled downpipe? Should I assume that the passengers side is the same design AND,,, will the comprehension difference throw off engine performance???

 

If the honeycomb is there, pull it out. Leave the other side alone - no need to go looking for trouble!. Two crushable per side, so you only need two.