I'd suggest that you remove the remaing part of the studs with one of these small Dremel disc grinders first.

Buy yourself a 5mm drill guide and some new 5mm drills. Use your old manifold as a jig plate.

If the drill guide is 10mm on the outside then drill your manifold with 9.8mm and press the drill guide into the 9.8mm hole.

Screw the manifold back on start drilling.

Hope this helps.

 

Sorry to be so late with my suggestion but I am surprised to see nobody talk about "mouse milk" penetrating oil. The best penetrating oil I've ever saw. We are using it in the aviation since a long time and when I first used it was surprise of the result.... I've had very good result to remove seized bolts on a turbine case....

http://www.mousemilk.com/

 

I've run a tap inside the heads and a die over the turbo studs (is that the right way round )

I've got some stainless fasteners to fit once I've got the old studs out and cleaned up the area

 

Thank you Stef, I've never seen/heard of those guides before

One question for you,

One of the holes in my manifold is elongated
Am I still ok to drill and fit the guide you mentioned into that hole too?

 

You should drill the elongated hole on a milling machine.

The elongated hole on a new manifold is 8.5mm x 10.5mm

 

Those bolts will have corroded more either because they are nearer the salty spray from the rear wheels or the others formed a better seal between the bolt head, manifold,gasket and head which didn't allow as much water in.

The longest looks a prime candidates for the "weld a nut on" method, once cleaned up the others maybe too. They need to be clean and shiny to get a good weld if you go this route

Those drill guides look good, are they readily available?, I presume they are hardened to stop the drill cutting sideways into them.

One thing to note, on my manifolds the hole in the manifold didn't line up exactly with the hole in the head.

 

I've only got around 2mm protrusion on the shorter studs, so I'm not going to try welding those ones

I'm going to try and find the drill guides, I really like the sounds of those

Question - Should I completely drill the old stud out, or should I drill a pilot into it and then try using an extractor on it?

This looks like the place to get them in the UK
http://www.boneham.co.uk/ShowProduct...?CategoryID=25

 

Just a thought,

If I refit the manifold to use as a jig, the manifold pipe work will block access to the bolt holes...... The drill will come into contact with the headers, meaning I won't be able to drill into it at the correct angle

Any tips?

 

Most drills come in standard size and in long size.
Something like ø5mm x 100mm and ø5mm x 150mm. Do some more googling. The UK is the #1 for these old style tools.

The drill guides are hardened indeed. It's a tight fit between the drill and the drill guide so you can't go sideways with your drill, that's the point.

 

Ant,
For the welding method you dont need enough stud to weld a nut on, all you have to do is weld a washer or a thin plate with a hole in it . Offer it over whatever amount of stud is showing and plug weld the stud and washer/plate together.
Then weld tack weld a nut of your choice onto the washer /plate.
Frank

 

Nice one Frank

We'll see how that goes

 

I would very, very highly recommend using any method of removing the studs other than drilling a pilot hole and an extractor. Extractors generally only work if the bolt/stud is not in very tight. If it is seized and tight the extractor can break off in the hole. Then you are F***ed!!! If you opt to drill, the hole must be perfectly straight and centered and you should drill it nearly as large at the stud to be extracted, so that there is a very thin wall between the ID of the threads. This way you are just removing mainly the threads. Also if you drill, drill all the way thru the bolt and use Freeze-off in the hole that will work its way up from the bottom.

Much better is to tig what ever you can, nut, bolt, etc to the existing stud and try to twist out while hot. I've used parifin wax like a candle that will wick in and lube while hot between an impacted stud and parent metal with success.

When you're done be sure to use plenty of anti-seize lube on the new bolts, perferably marine grade. GL!

 

That was going to be my next post

Just to add that the stud needs to be clean and shiny to get a good weld, and I degrease before welding too.

And

 

Ok, I've just gone for the welded-nut method

Waste of time, It did absolutely nothing

So, It looks like Stef's solution is next


Stef - I'm looking at the various bushes available, trying to decide which size to purchase

I can only get a 5mm bush with an 8mm outer diameter, which is too small for the 10mm hole in the manifold

If I get a bush with an outer diameter of 10mm (to match the manifold) I can choose from a variety of inner diameters ranging from 5.10mm to 6mm (in increments of 0.1mm)

I'm thinking if I go for the 5.1mm diameter bush the 5mm drill might wander around inside it too much

If I go for the 6mm diameter bush, will that leave too big of a hole to then tap a M8 thread?

Thanks again Stef

 

Sorry that hasn't worked for you,

going back to the drill jig have you thought about making your own bracket from some 1/4 plate so you could drill the hole for the bush what ever size you want?

another suggestion is to hand it over to a local indy who deals with this stuff all the time, and let them get the studs out, it would be a lot less stressfull

And