Hello. I'm attempting to take off the air intake manifold from the engine and for some reason two of the bolts just seem to rotate and not undo. The manifold is fixed fast and I've undone all bolts show apart for the two that rotate and the two brackets at the side. Is this usual or am I being lucky. Any ideas on how to remove the bolts?

 

I bet No. 2 is one of the free rotating bolts.
And the other one I can only guess: No. 1?
I can tell you why that is: Crappy design: Those bolts screw into insert-moulded nuts in the opposing plastic part.
1. Plastic should not have been used for these parts in the hot engine compartment.
2. Insert nuts should have not been used there.
3. And most of all: The design of insert nuts, because you will find that the outer shape of the insert nuts is not a hexagonal or similar, but it is round, just with a bit of a rough surface. So basically it is intentionally designed to fail - I can't put it any differently: I round bit of metal will turn in a round hole - obviously.

I had the same issue, but I knew what it is and I was able to just open those bolts.
Do I remember correctly, that those "bolts" were actually insert-bolts with nuts?

 

Hello Peter
You are right with No 1 but the other one is No 3. Nuts inserted into plastic does answer my problem and you're right plastic in a hot environment is down right stupid. Now I have a better idea I'll figure a way of removing the bolts. Thank you

 

I found the pictures I took when I had the same problem:


As you can see: On my 2.5L X-Type the right 2 bolts were actually not normal bolts like the rest, but insert-bolts with nuts on top.


This is how I removed the nuts. There is not too much you can do to fix that failure-design, I guess - I think I used liquid nails to "fix" those failed insert-bolts in their plastic-base again before re-assembly.

PS: That what looks like oil-stains on the air-intake around those 2 stubborn "bolts" ARE oil-stains, namely WD40 stains (or better use special penetration spray)...

 

Hello Peter. What an interesting problem, thanks for the photos and I've just tried to hold the washer and undo the bolt. I need either heat to break the washer off or WD40. Thing is I don't see how breaking the joint of the washer helps undo the bolt. The washer is on top of a plastic top hat and which is just a locater for the bolt. The mating thread is down the hole and I'm sure that's seized up causing the whole rotation problem

 

I was just hammering my brain about that as well - I took those pictures a while ago... and I would have taken the pictures, while I was trying to find a solution for the problem - maybe holding on to the washer did not bring me the solution back then... So try something else: Of course WD40 or better penetration spray (see the PS note I added to my previous post later).
Try this: use a spanner instead of a socket and hold the threaded part with the pliers (but very carefully, as you don't want to damage the thread...).

On the other hand - maybe I also succeeded with the "washer method" - I guess I would have - if there was already some play in the movement of the washer - tried to wedge the washer against the threaded part to stop it from turning....

 

I found 3 more pictures, which might help you:

Also note that the front cam cover is already shiny - the back one not yet... I also "shined up" the air-intake (using wire brushes on various power tools).

 

Hello Peter. Nice work, looks good. I'm leaving the fluid to do it's thing over night, fingers crossed. Cheers for the help

 

The other option you have is to pry up on the intake as you undo the bolts. This will pull the brass threads out with the bolt. Once you have the intake out of the car, you can then remove the brass inserts. From there, you can epoxy them back in. Just make sure to put in a bolt as a pushing device and something to ensure the epoxy does not fill the threads. You may also want to put some grease on the end of the bolt to ensure any epoxy is not going to stick to the bolt to make removing it later, easier.

 

That is the method I used a few years ago when i had the same problem. I haven't had to remove the manifold again, but hope the nuts inserts stay where they should be if I ever have to remove it again.

 

Or another idea I had meanwhile (if everything else fails and before cutting off the bold somehow): On those bolts with a nut on top:
Maybe try a metal saw to cut a slot into the bolt, so that you can hold the bolt with a flathead screwdriver, while working on the nut with a spanner. But I admit, this is difficult.
It may actually be better to use a metal file to flatten two sides of the top of the bolt, so that you can properly grab it with pliers, when working the nut with a spanner.
And yet again, even better than that might be to accept that you damage the top of the thread with strong pliers and hold the bolt tight with a lot of force, while working the nut with a spanner.
These are all last resorts before considering cutting off the bolts.
And once the nut is loose, you would have to think of something to get the nut over the damaged bit of the bolts - maybe cut the top section of the bold off somehow.
They just did not make it easy, when they designed engine parts from materials, which are not very much different from "paper mache"...

 

In some of your photos your rocker covers seem tp be polished alloy. My R/C are some sort of black plastic or have you painted yours?

 

Hi Domain58,
my best guess is that the material of my R/C is some kind of aluminium alloy - or aluminium.
My engine is a 2.5L. The 2.5L has those R/C. (my other 2.5L as well, and also my 2.1L).
My front R/C is shiny in the picture as I "restored: that one already: wire brush on angle grinder then wire brush on drill, then Clear coat - better than new.

You have a 3L X-Type. For all I know, this one should have the same engine as a 3L S-Type. The material of the R/C of my S-Type is another Jaguar design failure: It is magnesium or magnesium alloy. Magnesium loses the fight against aluminium and iron every day - what that I want to say: It dissolved over time due to electro-corrosion with aluminium and iron nearby.
I got myself new R/Cs for the S-Types.
My X308 V8 has plastic R/Cs, which is equally ridiculous as magnesium.
So I do not know, if you have magnesium or plastic R/Cs, as a 3L X-Type is not yet in my collection...
If you choose one little spot on your R/c and try to scrape away the black colour, then: If it works = probably magnesium, if not - plastic.

PS: Alternatively, I think you should be able to determine the material (metal or plastic) by tapping on it with e.g. a screwdriver - metal should sound different to plastic...

 

@ Domain58,
I found the picture, which tells the story of my 3l cam covers of the S-Type, which are probably the same as on your 3L X-Type:

In the front you see the old cam cover - note how the material dissolved itself - it just "melted away - that is electro-corrosion: Magnesium loosing the fight against aluminium and steel. Behind it the new cam cover, which I sourced myself in China directly - while they did not know exactly the material, they thought it may also be part magnesium, but it is supposed to be an alloy with only a small percentage of magnesium...

 

As per Thermo's instruction....I had to do the same on my 2.1 engine.
I used a flat bladed screwdriver to put some uplifting pressure on the shoulder of the bolt or washer while unwinding.
This effectively lets the knurled brass threaded insert gradually "chew" its way out of the glass reinforced plastic manifold spacer.
Once out, you have to get the brass insert to release from the bolt shaft, then clean up the knurling pattern of the brass with a Dremmell, ensuring there is some good bite reinstated on its surface.
Clean out the plastic receiving hole in the manifold, I chose to use the Dremmell's engraving tool (small ball) to add some indentations in the plastic for the epoxy to key into, then epoxied both the receiving socket and the brass insert and pushed in with one of the bolts until the right height was attained.
Left for 24 hours to cure fully and refitted.

 

Yes, I had the same problem not only on my 2.5L, but also on my 2.1L X-Type. This confirms, what I wrote before: Design failure.
I think it was mentioned here above before, but now that you repeated it, it sank in: Yes, good idea to fix this mess with epoxy, once the parts are apart.
So next time I come across such an issue myself, I will do it that way.
And again: cutting off any bolts should really be the very last resort - prying with a screwdriver (or as I did it (prying my tilting the washer with pliers)) or something like that should help in combination with penetration oil to get those stubborn nuts off...

 

Hello Peter. Well after a taking everyone's advise and trying each one in turn, only one method worked mine. I got the Dremel out with a EZ cutting disc and cut the heads off. I have to say after all the effort cutting them off was really satisfying. The annoying bit was when I removed the inlet manifold the bolts sitting there just came undone with ease
Thanks for all the help and suggestions from everyone, I'm off to buy two new bolts

 

Well, I had hoped that you would not have needed to go to this very last resort. So buy yourself some nice quality bolts now and replace the old remnants.
I just had to re-visit my own bolts. as I had to briefly remove the cam-covers. Picture below: While epoxy resin is a good idea, I did not have that idea back then and I had used liquid nails.
It apparently did it's job, as I had no problems this time to remove the nuts. Liquid nuts takes a very long time to really solidify, but it is solid now:

 

Hi Peter, thanks for the reply. On closer inspection of my car the front rocker cover is black but the rear one is dull alloy. A P/O must have painted the front one.
David B

 

I'll look in to that, the epoxy will need to be able to withstand 260c. I've found out the green and blue gaskets are made from Viton and the max temp for those is 260c. I did have another idea to fix the inserts securely by drilling and tapping an M3 hole to the side of the brass insert and tighten in a grub screw and use a temp resistant Loctite. Looking at the plastic manifold, it does look like it could take an M3 or M4 thread and I've many Loctite's at work that could suit the job. Thankfully the threaded bushes are at the sides and not inwards