Hello all,

as I have said in a previous post, my RH-side (passenger side on LHD cars) exhaust manifold was cracked and produced quite a bit of noise.

So it was time for a replacement.

After removing the air filter case and air ducting, it was easy to remove the heat shield and catalytic converter bolts from above, all bolts came off easily.
Working from below, it was no problem to undo the rest of the cat bolts, undo the oxygen sensor plug and remove the whole cat.

I started to remove the exhaust manifold bolts from the top, working from front to back. The first five bolts can be worked on from above, through the engine compartment. I used a short 3/8" drive ratchet with a 10mm socket.
The bolts came out well, but were hard to turn. Used some forth and back action as well as penetrating oil.

After that I started working from below and removed bolt #6. When starting with #7, I noticed that it won't budge, so I heated the cylinder head around the manifold flange with a propane torch. With the aid of heat I could extract the bolt in one peace with the threads in the head still intact.

On #8, the rearmost bolt, I went out of luck. despite heat, oil and swearing, the bolt broke off flush with the cylinder head.

So it was time to drill out the remains. To gain some more space, I removed the starter as well. I used an angle-type adapter for my drilling machine, and shortened the drill bits to work in the confined space.
I started with a 2 mm drill, and was able to pinpoint the bolt's center quite well. Then I proceeded with 3, 4, 5 and 6.5 mm drills, the last one being a good start for a new 8 mm thread. I produced a new thread in the usual three-stage tapping process.

The whole process took about three hours. I was very lucky that the rearmost of the bolts failed, I can not imagine doing that on one of the other bolt locations.

I had bought new bolts from Jaguar some weeks ago. When I took them out of their box, I found that the new bolts are quite a bit shorter than the original ones (see photo). The part # is AJ8 1316.
Also seen on the picture is one of the sleeves which are mounted on the original bolts.
I assume that these sleeves were intended to produce tension when they elongate as the engine heats up, or what else function could they have?


I would like to alter this arrangement by inserting fixed studs of 10.9 strength into the cylinder head threads. They could be long enough to accept a nut and washer, but not the sleeve. If the protruding end would be that long, I doubt the manifold could be placed on the studs due to space limitations.


What do you think, will the deletion of the sleeves have a negative effect? Most engine designs make do with simple stud / bolt arrangements....


Thanks for your thoughts
Stefan







old / new bolt and sleeve

 

So, I'm going to go out on a limb here, and please, if anyone disagrees, feel free to respond. I'm going on the basis of two things:
1) The torque sequence for exhaust manifolds I have replaced in my lifetime
2) Believe it or not, the spacers on the valve cover gaskets.


I've never replaced a jag exhaust, so if the sleeve fits through the manifold along with the bolt, acting like a spacer, I would go back to the dealership with an original bolt and take the sleeve with you to get the correct set-up. I say that because the spacer could very well be Jaguars method of preventing the bolts from being over torqued and cracking the new manifold, creating a new leak, just like they did on the.....valve cover gasket.


I may be wrong, but with everything you've done so far, why take the chance of having to starting all over again?


You wont look silly going back to the dealership because they handed you something different from your original set-up.


Just a thought...

 

I would first wire wheel the old, longer bolts, and see how they clean up. If the threads look good, why not reuse them? Use the spacers! They're supplied to allow all the same length bolts to be used to equalize torque on the manifold during heat cycles. Make sure all the bolts are torqued the same amount.

 

Marvin, John,

thanks for your replies.
Looking at the parts list, the correct part # exhaust manifold bolt for my car is JZB100087 which is described as 65 mm long, exactly as my old bolt is.
I will check availability with my Jag dealer tomorrow.
The old bolts do not look well, and one has snapped already...I'll go with new bolts to be on the safe side!
The specified torque for these bolts is 20 Nm, not much.

My thought was, using fixed studs in the cylinder head will not stress the aluminium threads any more when undoing the manifold in the future.

Best
Stefan

 

Can you find a stud that is long enough to allow the use of the spacers?

OTOH how much time spent inventing a better way may be influenced by the probability that it will ever be taken apart again.

 

Is there room to assemble everything onto the fixed studs if installed vs inserting the bolts?

 

Hey guys,

you're right, I decided to stay with the original setup. Went to the Jag dealer and bought the correct eight bolts (at a whopping 9 € each).
Today I installed the manifold with the new bolts, they came with thread locker already put on. All went well, tightened the bolts to 18 Nm as stated in my manual. The repaired hole with new thread was good as well, I'm happy.
Now hoping that all is gas tight, I will need some more days to complete the installation of the new stainless exhaust system.

I'll et you know how all that works out!

Cheers
Stefan

 

Hi,
I can only add both my manifold were cracked in more or less exactly the same position.
Could be a design failure?

 

Hallo all,

I finished the installation of the new exhaust system this weekend.
Upon attempting to start the car, I discovered that the battery was completeley dead, so I went and bought a new one.

With the new battery the engine fired right up and ran flawlessly. The manifold and exhaust system are gas tight, I'm a happy camper.

The exhaust system was supplied by David Roche, which was delivered very quickly and has a great fit and finish.
He offered various degrees of sound dampening, depending of silencer layout, I went with the most quiet version since the authorities here in Germany can be quite picky.
It still sounds much better, deeper, more V8-like than with the stock system.

I'd love to go for a test drive, but my car ist only registered March - October, so I'll have to wait.

As a conclusion, to remove the RH exhaust manifold on a LHD car is not that bad a task, as long as the bolts don't snap...

Best
Stefan

PS Lucadelta, I don't know whether these manifolds are prone to cracking. It seems to happen, but not that often as on the AJ6 / AJ16 cars.

 

Wait, wait, wait, wait....are saying you can only register your cars for 8 months in Germany?

 

Hi Marvin,

Hahahaha, no, it's not that bad!
I have the choice whether I want to register my car the whole year or a specified period of time. I could for example register a summer car from April til September and a winter car from October til March. The license plates are then marked accordingly.
Tax and insurance cost is cut proportionally.

Regards
Stefan