[xj] Repairing Broken Cylinder Head Studs. (Lengthy)

G’day to All Those Who’ve Managed to Snap a Head Stud or Two,

I recently had to remove the head from my son’s car, a SIII XJ6, due to
constant coolant loss between the head and the block. The head came off
fairly easily but it was obvious that the car had been run without the
correct coolant for some time. The water galleries were gunked up with scale
and rust flakes and the head gasket was actually installed upside down,
which wouldn’t have helped much. Anyhow I decided to remove the head studs
to check on their condition and managed to snap one off at the base. It
broke right where the thread started, about four turns out of the base of
the block. Examining the fracture plane revealed that the stud was cracked
around 2/3rds through, maybe torqued up too much when installed by the PO.

I removed the core plug to get access but couldn’t move the stud with vice
grips or heat etc so the options were to short stud the block or try and
drill out the stud remains and heli-coil the hole and use a normal long
stud. I spoke to the local supplier about the problem and he said that quite
a lot of local competition drivers use heli-coils for a lot of different
applications. He couldn’t see it being too much of a problem.

So I bought the right sized kit, actually made in Australia by a company
called Recoil, www.recoil.com.au and two extended length drills, one to
drill a pilot hole and the other to drill out the stud remains. The Recoil
kit thread tap is far too short to reach deep into the block as is the coil
inserting tool so I had them both extended to a suitable length, the same as
one of the studs, by an engineering workshop.

Now for the acid test, will it all work? I started by grinding the top of
the stud remains until it was clean and flat, and then used one of the old
studs ground to a point as a centre punch to mark the centre for the pilot
hole. Then I very carefully started to drill the pilot hole, at first
turning the drill chuck by hand until it bit into the metal a little, then
at a slow speed using the electric drill. Used plenty of lubricating oil and
removed the drill several times to clean out the swarf. I had previously
marked the drill with a paint stripe, using an adjacent hole as a depth
gauge, so I didn’t keep drilling into the sump. Once that hole was done I
then used the larger drill to drill out the stud so I could then use the
extended tap to prepare the hole for the coil insertion. Once again slowly
and carefully. The only thing that gave me cause for concern was when the
large drill stopped drilling with about a quarter inch to go. Hmmm, I
retracted the drill and poked around in the hole with a piece of wire and
all it was, was the non threaded end of the old stud lying in the bottom of
the hole. I remove it and finished drilling the hole. Now to tap it ready
for the coil. The stud hole in the top of the block is slightly smaller than
the tap, no problem, I just tapped that hole as well, it only left fine
thread lines in the top hole. The tapping of the bottom hole went smoothly,
once again slowly and carefully cleaning out the swarf regularly. The tap
just unscrewed through the top hole with only finger pressure. Coil
insertion, again required only finger pressure on the insertion tool. The
insertion depth collar can be placed on the insertion tool through the core
plug hole. Followed the instructions and broke off the tang, blew it out
with compressed air and presto job done. Screwed a new stud in the hole and
it went in cleanly with no binding. So now I have nothing to fear when I go
to remove the remaining three studs.

The bits I used;
Recoil Kit 7/16-20 P/N 34070
Small drill 3/16 about one foot long
Large drill 7/16 about one foot long, both made by Vermont American
Tap, from kit, extended to one foot long
Coil insert tool, also from kit, extended to one foot long.

The whole job took about 90 minutes max, and was done with the engine in the
car. I will also remove the remaining core plugs and clean out all the sand
and scale. I’ll post the photos when I get them developed

I hope this helps anyone who has the same problem, it ain’t that hard. if
you have any queries e-mail me off list.

Regards,
Jeff Watson.

1976 SII XJ6
1984 SIII XJ6 (with repaired head stud hole)
1985 SIII XJ6 Sovereign,
1985 SIII XJ6 VDP
1980 GSX 750 Suzuki
1970 Norton Commando Fastback.
All in Sydney,
Australia.

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G’day Again,

The remaining three studs broke when I tried to remove them. No big deal I
now know someone who can fix them for me. Guess what I’ll be doing tomorrow?

Regards,
Jeff Watson

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I note that you had to remove the casting sand from the water jacket. When I pulled the
head on the 78 XJ6, I had to flush out about 2-3 cups worth of casting sand out of the
water jacket…This is a pretty gross amount that should not have gotten by QC at
BL…

The Watsons wrote:
8<

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The Watsons wrote:

> Now for the acid test, will it all work? I started by grinding the top > of > the stud remains until it was clean and flat, and then used one of the > old > studs ground to a point as a centre punch to mark the centre for the > pilot > hole. Then I very carefully started to drill the pilot hole, at first > turning the drill chuck by hand until it bit into the metal a little, > then > at a slow speed using the electric drill. Used plenty of lubricating > oil and > removed the drill several times to clean out the swarf. I had > previously > marked the drill with a paint stripe, using an adjacent hole as a > depth > gauge, so I didn't keep drilling into the sump. Once that hole was > done

Did you at that stage consider using an ordinary screw-type extractor,
Jeff? Or would that be impossible due to limited access, or compromizing
heli-coil operation? Or any other difficulty?

Frank
xj6 85 Sov Europe (UK/NZ)

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G’day to you too, Jeff -

Congratulations - and thanks for the great post. I hope I’ll never
have to do it (fingers firmly crossed) but at least I’ll know where
to find all the info I need should that day ever arrive…

Cheers,
Loudon-
85 VdP6, Josephine, 77K miles
86 VdP12, Gypsy, 118k kms

At 18:34 +1000 4/20/02, The Watsons wrote:

G’day to All Those Who’ve Managed to Snap a Head Stud or Two,

I recently had to remove the head from my son’s car, a SIII XJ6, due to
constant coolant loss between the head and the block.

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G’day Frank,
To use a screw extractor I would have had to get it extended to reach the
busted stud. My previous experience with such extractors, with a really
tight stud, is that they aren’t up to the job, they break leaving a very
hard piece of tool steel right in the middle of where you no need to drill.
So I opted to go the way I did, which worked just fine.

G’day Art,
On another engine I had rebored and chemically cleaned, I noticed when I got
it home traces of sand in the galleries. So I stood it on it’s end and dug
aound through all the water jacket holes with long chisel shaped rod and
managed to collect around two cups, maybe more, of casting sand. Amazing, it
certainly goes along way to explaining overheating problems with some
engines. I have friend with a Triumph Stag and he said it was standard with
an overheating problem to take out the engine and clean out all the sand,
problem gone. All thanks to Bloody Leyland lack of QC.

Regards,
Jeff Watson.

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Because it creates such a serious problem, I want to add my experience with
reverse-spiral screw extractors has also been breakage!–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

The Watsons wrote:

G’day Frank,
To use a screw extractor I would have had to get it extended to reach the
busted stud. My previous experience with such extractors, with a really
tight stud, is that they aren’t up to the job, they break leaving a very
hard piece of tool steel right in the middle of where you no need to drill.
So I opted to go the way I did, which worked just fine.

G’day Art,
On another engine I had rebored and chemically cleaned, I noticed when I got
it home traces of sand in the galleries. So I stood it on it’s end and dug
aound through all the water jacket holes with long chisel shaped rod and
managed to collect around two cups, maybe more, of casting sand. Amazing, it
certainly goes along way to explaining overheating problems with some
engines. I have friend with a Triumph Stag and he said it was standard with
an overheating problem to take out the engine and clean out all the sand,
problem gone. All thanks to Bloody Leyland lack of QC.

Regards,
Jeff Watson.

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The Watsons wrote:

G’day Frank,
To use a screw extractor I would have had to get it extended to reach
the
busted stud. My previous experience with such extractors, with a
really
tight stud, is that they aren’t up to the job, they break leaving a
very
hard piece of tool steel right in the middle of where you no need to
drill.

I thought as much, Jeff. We’ve probably all had some experience with
that one. Somebody should perfect an extractor extractor… :slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

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Hello Jeff, Art and all,

Do you think that some of the sand that was found in the block was the
notorious factory-installed stop-leak? 2-3 cups is a HUGE amount of anything
solid, even if in particulate form, to have in the cooling system.

Hank
'84 XJ6 SIII

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I do know that casting sand is used to create the voids that become the cooling
passageways. I do not know if that was a form of stop leak. The sand was very fine pure
silicates, like casting sand…

Jaghpo@aol.com wrote:

8<

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G’day Art,

It sure sounds like a lot of sand, however when I removed the core plug to
access the broken stud on the engine I’m working on at present you couldn’t
see the top of the broken stud for all the sand and rubbish in the bottom of
the water gallery. There was about 1/4" of the stud standing proud of the
base of the block, so you could safely say that there was 1/4" or more of
sludge/sand throughout the whole block. With the engine I had chemically
cleaned I was surprised that there was still so much rubbish in the bottom
of the galleries, it was really solid and I had to dig it out with a chisel
shaped rod. No amount of flushing would have ever removed it. I don’t know
of any solution you could use to dissolve or otherwise free up the
collection of sediment, that I have experienced, that would be effective
without being harmful to other components of the engine. My local radiator
guy tells me that the only real way to remove sediment/scale is to
physically dislodge it, none of the "flushing"compounds are really
effective.

Regards,
Jeff Watson.

1976 SII XJ6
1984 SIII XJ6 (with repaired head stud hole)
1985 SIII XJ6 Sovereign,
1985 SIII XJ6 VDP
1980 GSX 750 Suzuki
1970 Norton Commando Fastback.
All in Sydney,
Australia.

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Did you at that stage consider using an ordinary
screw-type extractor,
Jeff? Or would that be impossible due to limited
access, or compromizing
heli-coil operation? Or any other difficulty?

Frank
xj6 85 Sov Europe (UK/NZ)

I never once been successful with an extractor. In every
case, it just expands the stud which wedges it even more
tightly.

But, Snap -On tools makes a set of reverse-twist drills.
I’ve found that drilling the stud with these will
frequently catch and remove the broken part.

Also, before removing studs, unless the stud is VERY thin
from corrosion, a good whack downward with a hammer
before you begin will usually loosen it and prevent breakage.

Marvin

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and the good whack will let you know which studs to replace without removing the cylinder
head when the narrow part breaks…8-(…

marvinmatch@attbi.com wrote:

Also, before removing studs, unless the stud is VERY thin
from corrosion, a good whack downward with a hammer
before you begin will usually loosen it and prevent breakage.

Marvin

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marvinmatch@attbi.com wrote:

I never once been successful with an extractor. In every
case, it just expands the stud which wedges it even more
tightly.

But, Snap -On tools makes a set of reverse-twist drills.
I’ve found that drilling the stud with these will
frequently catch and remove the broken part.

Also, before removing studs, unless the stud is VERY thin
from corrosion, a good whack downward with a hammer
before you begin will usually loosen it and prevent breakage.

That was a new twist, Marvin, and a very good one, too! Worthy of
archives. Never saw a reverse-twist drill down here, though, but I’m
lookin’. Now for those pesky left-hand threaded screws… :slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

Marvin

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G’day Frank,

Have alook here for left hand threaded stud extractors.

www.recoil.com.au/p_range_DrillOut.asp

They are made by an outfit in Melbourne, Oz. All the contact details are in
the main site.

www.recoil.com.au

There’s quite a lot of info about thread repairs of all sorts as well as
downloadable brochures etc.

Here’s a supplier in En Zed for you.

www.schrodoco.co.nz/new_page_4.html

Regards,
Jeff Watson.

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G’day All,

I’ve finished the last three remaining broken stud repairs and all went
smoothly. The last two only took about an hour to do both. All I have to do
now is finish digging out the rubbish in the coolant galleries, replace the
core plugs and replace the head. sounds easy enough. Ha Ha Ha, we all know
the truth.

My son took the radiator out while I was working on the block and took it to
the local radiator repair workshop to be rodded, the problem is that the
core was so old and corroded it couldn’t be done so I had it re-cored.

Regards,
Jeff Watson.

1976 SII XJ6
1984 SIII XJ6 (dredged ! & recored & stud repaired)
1985 SIII XJ6 Sovereign, (dredged ! & recored when I get around to
putting it together)
1985 SIII XJ6 VDP (rodded)
1980 GSX 750 Suzuki
1970 Norton Commando Fastback.
All in Sydney,
Australia.

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In reply to a message from The Watsons sent Sat 20 Apr 2002:

G’day Jagsters,

The photos I took that go with original post can be found here.

http://www.jag-lovers.org/v.htm?1021296272

Though I’ve just noticed the note to the left of this page which
says ‘No HTML allowed’, so the link wont be active and you’ll
have to cut and paste it to see the pics.

Regards,
Jeff Watson.–
XJ6 SII, XJ6 SIII, XJ6 SIII Sovereign, XJ6 SIII VDP
Sydney, NSW, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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G’day Jagsters,

Looks like I got the wrong idea about the active link.
It works fine.

Regards,
Jeff Watson

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G’day Charlie,

Thanks for the info.

Regards,
Jeff Watson.

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