Hi,


I am restoring a 1982 Daimler Sovereign XJ6. Have dismantled head and put on new gasket and all is well when one of the head bolts stripped the threads in the engine block.


I am looking for any suggestions on a fix and where I can get the parts to do the fix.


Obvious one is re-drill and tap - does anyone know where to get the extra long drill and tap and oversize cylinder head bolt to match.


Thanks in advance


Skelly

 

These work.
http://www.timesert.com/html/universalheadbolt.html

You will not need an oversize studd once you repair the threads with the timesert.

Use a sleeve to pull the studd out byb tighting the upper threads....use with wood on the deck to protect it.

 

Go Amazon or Ebay search, or merely Google.


Simplified by using a thread insert process as mentioned here. No tap needed. but, still might need a long drill, to clean up.


I have a selection of longies. One is merely a bar with a means of chucking a common drill in one end. Where are you? Perhaps a loan via USPS is feasible.


Which hole. A blind one or visible via a "core plug" or heater plug?


Bad, or might they be cleaned with a blind tap ?


How did you manage this? I am good at it, I admit.


Are your studs clean and have sharp threads or battered?


Are the holes in the block absolutely clean, all the way down ? An essential.


Remove the head to do the work. Much simpler and less likely to mess up, again.


Apologies for the criticism Been there and done that, but in other critters.


Carl

 

Many thanks icsamerica and JagCad.


The Timesert is a very interesting item but the good old Jag is problematic for this solution. Believe it or not the great British design decided they would pass the bolt all the way through the engine block, through the water jacket and put screw holes at the bottom (almost inline with the crank).


JagCad, thank you for your very kind offer but probably not practical as I live in Auckland New Zealand. The hole is number 3 (one up from the centre bolts) and I think the cause was the bolt hole not being fully cleaned and the stud then only gripping on 1/4 of the threads (novice error on my part).


I think my first attempt at salvaging this will be cleaning the hole out (somehow) and getting the original thread sized tap in there to clean up.


Because the hole is very limited in diameter and the depth is about 10'' I need to get inventive with welding a 'T' bar on the tap. I will also look at access via the core plugs.


Still open for suggestion.


Thanks


Skellly

 

Most (if not all) of the head bolt anchor areas have a casting plug at the location.
I would suggest removing the casting plug and examining the threaded area.

I have removed broken head stud 'remains' from the block by pulling the casting plug and welding a nut on the top of the broken bit. I placed a socket on the nut and dropped an extension on the socket to remove the threaded section from the block allowing me to install a NEW stud.

This is with the head REMOVED but more access is gained with the head removed anyway.

I would imagine this technique would work with a TIMESERT also.

bob gauff

 

What is the symptom that tells you the block threads for the long studs are stripped ? Stripping of these threads is almost unheard of, but what is common is for the studs themselves to corrode so much that they break when any torque is put on to them. As you are aware the studs are continually bathed in coolant, and if the stuff is replaced regularly, corrosion is not too bad, but over the years owners get rather neglectful and the studs corrode badly with no inhibitors in the coolant. Some owners just put plain water in !!

So you might think the threads have failed because the head nut turns round and round, but try pulling the long stud out. It is sure to be snapped off leaving a short stub in the tapped hole.

Getting these stubs out can be very difficult and is next to impossible without removing the core plug next to the stud housing.

Of course if it is the block threads you have a big problem, and maybe another block is the answer.

 

Thanks motorcarman,


That's a brilliant idea.


I removed a core plug and there was lots of dirt which I removed. It looks like some of the casting fell in the hole and stopped the bolt going all the way in.


I will try and drill this out tonight and hopefully there will be enough threads left for the bolt to screw into.


If not it will look to plan B with Timesert.


Thanks for all your helpful suggestions. Its rally does help.


Skelly

 

Hi Fraser Mitchell,


My initial thought of the engine block threads being stripped was because the stud threads were a little damaged but not stripped and I could not get the stud to engage in the hole in the block.


I have now removed the core plug which has helped determine what the issue is. The threads in the engine block has got some metal stuck half way down the hole. This caused the bolt to not fully engage the threads (the stud has about 1/2" at the end with no thread as part of the design).


I am hoping that clearing this by drilling out the stuck piece of metal (but not drilling the threads) will give me enough thread left for the stud to engage and have enough depth to secure the head to the right torque.


A voyage if discovery as I go


Cheers


Layne

 

OK, from your last post the thread has stripped. Before you rush to drill things, get the correct size tap and bronze-weld a t-bar onto the end so you can insert from the block deck hole and clear out the threads. First-off though, get a length of plastic tube with a V-notch in the end connected to a vacuum line and vac out the tapped hole, then clean out with the tap. These long studs are machined with a small projection at the end of the tapped length that is supposed to bottom on the hole and tell you the stud has been inserted fully. The tapped length is quite long, longer than the head nuts, so you should be able to get sufficient thread to secure the studs.

Of course if it all fails, go down the TIMESERT route.

Really sorry to hear you're having such trouble ! I rebuilt a Series 3 engine in the early 90s but had to buy an uncracked block as my engine was pre the slotted blocks. Car went well afterwards and was on the road in 1995 and finally sold in 2003. I toured Ireland in it in 2001 !!

 

i have had good luck with the Timesert method.

but it really boils down to the magic of the mechanic doing the work, i have repaired 100s of engines , and i have come to believe in my hands sometimes are smarter than my head! lol,lol.

 

A big thanks to all of you who took time to help me with your great ideas.

Had a good break through. I got the stuck bit of metal out, cleaned up the threads on the block and stud, screwed the stud in and torqued it up.

I am feeling happy and relieved.

Once again - thanks

Skelly

 

Well done, congrats ! Long studs bathed continually in coolant are not a good design feature, but the V12 has them as well as the 4.2 sixes. All is normally OK if the anti-freeze is replaced regularly to keep the inhibitor strength up, but lots of people just don't bother and in hot climates just put plain old water in.