Freelander 1 TD4 Engine, injector studs replacements / alternatives - requirements?

Long story short I have had to helicoil some of the threaded holes for the injector studs, and the studs threads weren't brilliant, so I've dressed them with a thread file and or chased them with a die as required, but I'm not 100% happy with them. I really dislike the idea of less than perfect studs going into helicoiled holes.

Yes, I know I can get replacements, but they are ~£37 a set 10 years ago, and dealer only, and we are locked down. And as these studs need removed to remove the rocker cover, and they've got the nut half way down, these could be in and out a few times, and personally I think of a helicoil as a set it and forget it, not something I want to be running revisiting...

So; I'm toying with the idea of thread-locking generic / home made m6 studs into the head, cutting the original studs to salvage the captive sleeves, which are held captive by the rolled threads head side of the studs. Then once I've retrieved those little sleeves I'd set about enlarging the holes to go over the threads on the new permanently attached studs.

Then for reassembly I'd fit the rocker cover by sliding down the studs, then put on the sleeves, and securing them with large flanged nuts over these new permanent studs. Then fit the injectors & collars, which would also go over the new permanent studs and be secured with more large flanged nuts.

I've got some cute little M6 stainless machine screws which with an angle grinder could be decapitated to make studs, and with my lovely little chamfering tool like this one:

...they'd be quite nice when permanently affixed.

But, with the original studs being rolled threads, I'm having second thoughts... The rolled threads suggest to me that these are high tensile? So; I don't know what grade of bolt I'd need for this to work? Would the A2 marine stainless fasteners be sufficient? If not, what about grade 8.8? Or would I need to go for 10.9?

Wouldn't just be easier to get a replacement cam cover? They don't get much money on Ebay?

You could make up something, but I can't see it'll be worth your time.

Morning John, it's not the cam cover the (damaged) threaded holes are in, the threaded holes are in the cylinder head. I've painted the locations of the holes with yellow dots in this diagram...


The studs are these ones:

*stock picture from island 4x4 - part number LR009825 normally sold as a kit of 8, they sell them individually

These studs go through the rocker cover, the threads on the bottom left go into the holes located at the yellow dots, the black rubber sits inside the cam cover, then the injectors collars go over the thread on the top right and are screwed down by nuts to pull the injectors into place.

I've discovered these last night, stainless steel solid threaded inserts (m10 male outside thread & m6 female inside thread)


I'll probably give it a go with its own studs and the helicoils this afternoon, and if that doesn't work I'll order these and some 10.9 grade m6 x 70 studs.

Jayridium said:

Morning John, it's not the cam cover the (damaged) threaded holes are in, the threaded holes are in the cylinder head. I've painted the locations of the holes with yellow dots in this diagram..

Click to expand...

Got ya.

Jayridium said:

I've discovered these last night, stainless steel solid threaded inserts (m10 male outside thread & m6 female inside thread)

Click to expand...

I'd probably go with those, as it'll be stronger than the helicoil.

I don't know what grade the standard bolts are, but 10.9 grade bolts should be more than up to the job.

Hi John, thanks for the reply, I should have updated the thread earlier...

One of the original studs broke yesterday afternoon, GRRRRR!

So after a bit of a temper tantrum, all the threaded holes for the injector studs are now drilled out to 8.5mm for the m10 inserts. I've also ordered a nice set of m10 taps (I've only got taper taps in my tap and die set), 10x of those inserts, and some m6x80 grade 10.9 all threaded countersunk cap screws, and the screws will be "surgically altered" into studs.