v12 downpipe

[kelsham]

My xjs was due an MOT. While checking over the car I found a small blow on the LH downpipe where the bottom flange was welded on. the application of exhaust sealant round the flange temporarily sealed it off for the test.

Having passed the MOT I scraped off sealant and realised the pipe was very thin all round the flange.
Time for a new downpipe. Several hours of barked knuckles and much profanity later, I had dropped the steering rack and managed to undo 1 nut, remove one nut and stud which came out together. Sadly the other two nuts sheared off leaving the stud protruding. They both sheared after I had applied heat to the nut. I had hoped the heat would expand the nut allowing removal.

Jaguar must have anticipated such difficulty because there are two spare holes ready tapped to take replacement studs.

This would need the old studs to be cut off flush with the manifold and new studs and nuts to be fitted.

SNG Barrat supplied the parts last time I carried out this job on the RH downpipe, the replacement nuts were brass which seems very sensible to me, instead of the metal nuts Jaguar fitted originally.

Two problems remain, first in spite of the flanges being undone the pipe has welded itself into the manifold and reasonable force has failed to dislodge it so far.
The second problem is that once I alter the position of the studs the fixings for the heat shield will be in the wrong place.

OK so unreasonable force may succeed and is being contemplated.

The second problem, I have been contemplating wrapping the pipe with heat proof tape, but will probably make new fixing brackets. Shipwrights disease is looming and I am eyeing up the rear subframe mounts and considering replacement.
Regards Kels.

[PaulGover]

Kels,
You have my sympathy - I had to cure a leaking flange last year, and it cost about a week and the skin off several knuckles.

My guess as to the first problem is that the joint was coated with "Firegum" or similar before it was assembled. It cooks up hard, but is brittle, so it should crack if you heave the pipe around enough. I vaguely recall it might be water soluble, so there may be mileage in spraying the joint with water. Then it's a matter of getting the socket cleaned up to fit the new sealing olive.

[kelsham]

I have now removed the airbox to help access, nice to know I am not suffering alone Paul.
Having introduced a lump hammer and piece of bar into the equation without any hint of succes I am presently applying plasters to my hands.
The piece of bar was to hit the downpipe, not to drink in. Though who knows where I will be driven by frustration.

I had considered water, for the pipe. But, not easy to reach the firegum. I am beginning to think more violence on my part might crack the manifold.

I am pondering cutting the downpipe in two before it joins into a single pipe. Hopefully it will be easier to move it one piece at a time.

A further problem is the repacement downpipe I sourced off Ebay, sadly the quality is very poor. Where the pipes join into the single pipe they have been tortured into shape with no regard to correct shaping. The pipe looks restricted to me. Any one else fitted one off Ebay? I have asked the supplier to take it back but it has gone very quiet his end.

If i can get a refund I will pay the extra for a genuine Jaguar pipe.
That is the problem with Ebay you cannot inspect the parts before buying.

Regards Kels.

[Brakebuster]

if your after a near side exhaust down pipe for a V12 , the part that splits from two to one from the manifold then i have a genuine Jaguar one going spare,

i bought a pair but only ever required the drivers side

pm me if interested

either way , good luck with the task in hand.......

BB

[kelsham]

Update, I have sent the exhaust down pipe back, and received a refund.

I have collected the pipe offered by brake buster. Thanks Vince, sorry we could not talk longer. Wife gets impatient left in the car.

I have ordered new studs from SNG Barratt and just received new compression gaskets from Ebay.

Once the studs arrive I will be forced to return to the fray.

I am eyeing up the rear front subframe mounts for replacement.

I bought some a couple of years ago and after looking underneath failed to proceed.

Regards Kels.

[kelsham]

Been carrying the downpipe round in the daily driver since I collected it.

Replacement bolts arrived from SNG Barratt yesterday, running out of excuses.

I decided to try and drill out the broken stud, by a miracle I found I could get the drill up inside the engine bay and just reach the broken stud. Jaguar designers slipped up this time.

I used Dormer drills and gradually went up in size. Failed to move the remains.

I need one size drill larger than I have, so effort stalled.

I could just rotate the flanges and reposition the studs but this would stop me using the heat shield in its present form.

The heat shield is there to spare the steering hoses, so not wise to discard it.

I have also removed the small rubber hoses that connect to the oil filter housing, I won't ever be able to reach them so easily again.

Just need to source them from the hose shop in Newtown.

Kels.

[CliveRothwell]

If it's still road worthy, I'd take it to Kwikfit. Jobs like these are not fun to do and as you are finding out, other things crop up like to studs being extra hard now that they have been heat treated for the past 15 years or so. £50 quid and the cost of a phone call will have you smiling. (I know it's not the done thing in this forum but for some of us, the whole point of owning a Jag is to drive it! )
Good luck anyway
Cheers

Clive

[kelsham]

Clive, I doubt Kwik fit would touch replacing a front pipe. If they did it would cost much more than fifty pounds. Moving the steering rack and heat shields just to access two nuts is intimidating to the average fitter.

In any case I like the suffering, particularly when it stops.

My car already has damage from an exhaust specialist, not Kwik fit.

They found it difficult to replace the pipe that threads through the rear subframe. Their answer was to cut the subframe with a hacksaw and prise the ends apart. They should have removed the drive joint shield when the pipe would have slid in. The subframe was pushed together and left after this assault.

Doing it myself has allowed me to send back the first downpipe because of quality concerns.

At the moment I have drilled out and tapped the hole where the stud broke.

The new downpipe is in place, I just need to refit the steering rack and check the tracking.

Shipwrights disease is in the air and I have started to clean off the airbox prior to respraying it.

One snag arose, I have noticed a pinhole in the straight pipe the other side of the flange, I now need a straight pipe.

Kels.

[dhdove]

Cut the subframe with a hacksaw and prised the ends apart......
Surely not....

Anyway I would never entrust any of my cars to Quik- fit.... Bunch of cowboys.

Just my opinion.....

TonyS

[kelsham]

Yes they cut the subframe and left the ends touching. I have the Dana diff and there is not sufficient clearance with the shield fitted to allow the pipe to thread through the subframe. It was not Kwik Fit, but a self styled exhaust specialist who did the deed.

I prefer to do my own repairs to ensure the quality of the work. It also allows me to spot other problems that the average mechanic would not even think needed attention.

For instance whilst doing this exhaust, I have replaced the small pipes that are attached to the oil filter assembly as they were easy to reach and looked in poor condition.

I also noticed a couple of areas where the underseal has been breached and have repaired the damage.

The airbox is about to be derusted and sprayed while I have it on the bench.

Regards Kels.

[Brakebuster]

Kels

great news your getting on with the jobs that need doing,

sorry for the delay in responding, have been away to the IOW for my holls ,

got any pictures ?

BB

[kelsham]

Job practically completed, just got sidetracked into dealing with rusty airboxes. Will be going to the Beaulieu Autojumble, I may be able to get the straight pipe I need there. at the moment I have bodged it with a repair kit.

Next job is to look again at the leaking targa roof. I have already changed the seals without success.

Regards Kels.