head studs -- what have I done...?

[jeremybarnes]

So I thought I was being clever when I decided to add the front lifting strap to my engine, because it was bugging me that it wasn't there. I removed the acorn nut, but found it to be welded firmly to the stud, which unscrewed all the way out the block. Yup, cue the scary music...

At this point, i decided to just put the stud back in and pretend it was all a bad idea, but managed to cross-thread the stud. Cue the even scarier music.

I purchased a new stud, which I now can't get to go more than a couple of turns into the block. Pulled it back out, and I found the end is wet, which I understand isn't quite as terrifying as it seems, when I do a forum search. So here's where I am now, and I think I need some advice (and possibly a quaalude or two to calm my nerves...):

- the stud is the second one back on the intake side, where the front lifting strap should attach
- called XKS Unlimited to order a replacement, the nice man said i need the one with the shoulder on one end, which I find can only go in in only one direction, because the large shoulder won't fit into the head
(separate point: If I was building the engine from scratch, wouldn't i have installed this stud into the block before I dropped the head on? And if so, how would I have made the head slide over the wide shoulder?)
- the new stud's large shoulder is so big that the lifting strap doesn't slide over it, so how could I get it far enough into the block in order to get the strap and the acorn nut on top?
- do I need to drain coolant to some level in order to get rid of the water in the stud hole, or do I just need to do the double-nut trick and try harder to get the stud in (although this still doesn't address the wide shoulder issue...)?

So...
- do I, in fact, have the wrong stud?
- Is this situation fixable, or have I resigned myself into pulling the head because I've, in some way, broken the seal on the head gasket?
- I also purchased the plug-wire channel piece that runs inside the valley of the head, because my engine was missing that too and i needed plug wires anyway, but I'm now justifiably terrified to remove any more of the acorn nuts to install it, for fear of pulling more studs out. Not doing that is a good plan, right?

Thanks in advance for the advice of those smarter than I on this subject. I'm very scared that I've done something horrid here...

Oh, in case it's of value, the chassis number is 1E33679, the engine number is 7E10780-9, production date is 25 October, 1966.

Jeremy

[Mich7920]

Hi,
Photos could help...
Mich

[MarekH]

If you have water in the threaded hole then you will be able to screw nothing into it until the water has been removed. You can't compress the water out of the gap when there is no gap for the water to get out of the hole.

kind regards
Marek

[abowie]

OK I'm assuming you have a short stud block.

Coolant can access the stud holes and as Marek says this will interfere with inserting another stud. So drain the coolant.

The stud you're talking about has a thicker (dowelled) section that acts to accurately locate the head on the block. I have never tried to put a stud in with the head on but I doubt you'll be able to get it in as I suspect the dowel is wider than the hole in the head. I don't think this matters however as your head will be well and truly solid with all the other studs. So I would just use a standard stud of the correct length, like the one opposite it.

You will need to run a tap down the thread in the block. Personally I think the safest way to do this would be to take the head off and get the thread repaired or helicoiled professionally. However..read on..

You an also tap the thread in situ. You will need to make up a long tap by welding the correct tap to a piece of rod. To do it properly, I would actually make 2 long taps. One a standard thread starter one with a tapered end. The second needs to be a straight edged tap so that you cut the bottom of the thread flat. You might be able to get away without the second tap if the only damage you've done is to the first few threads though.

So this is how it would go. Blow out the water etc with compressed air. Run the tapered tap down first and then clean out the crap. Try to insert your new standard (non dowelled) stud. If it bottoms out and tightens up well you are probably ok to leave it there. Put your lifter bracket back on tighten down the nut.

Now if the stud won't go down all the way, use the strait edged square faced tap and get the thread good and clean right to the bottom. Make sure it is all scrupulously clean. See if this fixes it. The stud MUST go all the way in or the nut may just jam down on the top of the stud and not apply torque to the head.

If this doesn't work the thread is probably too damaged and will require a helicoil. It might be possible to do this with the head in situ, but I've never attempted that. At that point you curse, feel unlucky and take the head off.

Best of luck.

[PeterCrespin]

Sounds a mess, best of luck indeed. but if it's a short stud block it hardly matters that the threads are wet because the hole goes through the deck.

The only ones that are blind IIRC (and could therefore even theoretically suffer from the incompressible coolant effect) are front and rearmost ones, which don't get wet on any XK, or the lower block threads on long-stud engines, not short stud.

Pete

[jeremybarnes]

Thanks everyone, appreciate the input. Honestly, not the words I was hoping to hear, but the truth hurts sometimes!

First off, I'm not sure how to identify a short- or long-stud engine. Any tips, and what it means if I have one or the other?

Either way, here's my plan forwards:
- bought a non-shoulder stud, as suggested, and will use that in place of the shoulder one when it arrives in a couple of days
- will drain the coolant this weekend
- will clean and dry the hole the stud screws into (compressed air and a q-tip should dry it out)
- will try to (gently) screw the new stud in, but be ready to try a tap if i have to
- and if it all fails, I suppose the head comes off...

Ugh, live and learn, and I will NOT be removing the other acorn nuts to install the spark plug conduit!

Thanks everyone, and I'm open to any other suggestions...

Jeremy.

[288gto]

Hi Jeremy, ref long or short stud, how long is the stud you have taken out? How many core plugs do you have in the sides of your block. In theory if it is the original engine it should be a short stud block where the head studs screw into the top of the block. The long stud block was introduced around 1969 and the studs pass through the top of the block, through the water passage and screw into the bottom of the block just behind each core plug. Now these really are a pain to sort! Hope you manage to fix it. As others have said the hole must be spotlessly clean and now having damaged the top of the thread I really would invest in a tap rather than try to use a stud to clear it.

Simon

[politeperson]

So- in summary, you have a short block engine ( 7E10780-9) ,and you have unscrewd the 2nd row head stud.

This threaded hole will be full of water, because the hole opens out into the water jacket.

The solution therefore, is to re-tap the hole as recommended above, and screw it back in again.

Good luck.

[PeterCrespin]

- bought a non-shoulder stud, as suggested, and will use that in place of the shoulder one when it arrives in a couple of days....and I will NOT be removing the other acorn nuts to install the spark plug conduit!

Thanks everyone, and I'm open to any other suggestions....

My suggestion is to do it properly and not trust to luck and half measures:

1) The stud came out because the acorn was jammed and therefore not clamping correctly despite (presumably) full torque. Somebody has 'screwed up' royally to do that. It is probably not the only thing they did with their eyes shut.

2) You should assume at least the corresponding lifting bracketless stud/nut assembly is also messed up. The only correct thing is to not trust ANY stud to be in the right place and correctly clamped, even if checking with a torque wrench indicates full torque.

3) If you somehow substitute a plain stud for a dowel stud you are degrading the integrity of the alloy head/iron block joint. Not good.

Do it once, do it right and take the head off, before assembling everything to a known correct standard. Your call. This all assumes you don't have the original head on a late replacement block (i.e. the head and block numbers are the same). In practice, the technique in the matter of clamping clearance is the same for any acorn nut fastener.

[Alty Ian]

I agree with Peter.

Taking the head off isnt a huge job, you can also then check out ALL the studs and/or replace them, easily helicoil any damaged threads, decarbonise the engine and head, clean out all the waterways and generally improve performance.

Do it right, do it once.

[jeremybarnes]

Okay, thanks everyone for the replies. Not what i wanted to hear, but there you go...

Any particular tips for pulling the head, then? Any do's and don'ts? Any tricks that the workshop manual won't tell me, to avoid issues? Am I likely to fight this thing to get it up over the studs, or do I remove the studs before trying to pull the head? And when I put it back on, anti-seize on the studs to help it slide down, or dry?

And lastly, a question about the head while it's off: What's involved in decoking? Am I best advised to send it to a machine shop to replace the valves, or just a proper cleaning is sufficient? This is the original head and block.

Jeremy.

[Alty Ian]

Jeremy
I had to remove my head due to an annoying oil leak not very long after it was restored, if you look at this link there are some pictures. viewtopic.php?f=3&t=9020

The tips I would give you are as follows;
1. Get a timing key and timing tensioner tool, both cheap.
2. Follow the workshop manual steps except it IS possible to remove the timing bolts from the end of the camshafts without rotating the engine if your timing is already good and the timing chains are correctly tensioned. As long as the engine doesnt turn, you can slacken off the timing chains a bit and re-tighten later, just make sure the timing key is always fitted when doing that.
3. Remove the lock wire and the outer bolt can easily be removed, then slacken off the inner bolt using a thin ring/open end spanner to a point where is halfway out then run a piece of lockwire through the hole in it and holding both ends you can rotate the loose bolt out and the wire stops it falling into the sump. Replacement is a reversal of this process. The manual tells you to rotate the engine to get each bolt out but if you do that then you have to redo the timing completely.
4. It is possible to remove the exhaust and intake manifolds sideways without disconnecting them from anything as shown in the pictures of the thread above. Just use pleny of blankets to protect what they rest on.
5. Decarbonising is easy just use a blunt chisel or similar tool to get the crusty stuff off, take great care with the pistons and head which are aluminium and easily scratched, use fine emery paper after that. Make sure you blow out the cylinders with compressed air well.
6. On the head, before you start taking the head off, measure all the valve clearances (carefully note the sizes of the existing tappet shims to see what adjustments are needed) and get a spring compressor and take each valve out and check valve guides for wear, if OK just gently lap each valve into its seat to make sure they are airtight. When head is back on with revised shims to get correct gaps,... remeasure the tappet gaps again just to be sure. Lapping the valves will affect the gaps if you find they really needed doing, if so you may need to take the cams off again to revise tappet shims again.

Once done, you should find the engine performs miles better, and quieter if you tappet gaps were out.

Good luck, lets us know how it goes.

Ian
7. Wash out the water chambers in the head with a power hose while its off.

[Gfhug]

Jeremy

Just to add to Ian's very clear and comprehensive instructions, be careful to use an old cloth to catch any bits (cut locking wire, washers, etc.) from falling inside the engine.
Having followed the instruction book and advice from on the forum I've taken the head off my engine and it is not a difficult task.

Geoff

[64etype]

Yesterday I was prepping for first engine start after lengthy engine rebuild. Pulled all the spark plugs to spin the engine on the starter. Just happened to notice a piece of debris sitting on the edge of an open spark plug depression...looked like a thin piece of wire. I got a magnet to pick it up. The wire lifted on one end...and then dropped directly down the spark plug hole into the combustion chamber. It was a wire from a stainless steel wire brush. Panic city! I could see it sitting on top of the piston (not far from an open valve), but my magnet wand would not lift it. Ended up sticking a blob of supper sticky black mastic on the end of my magnet wand and gingerly pressed it down on the top of the piston. Got it! My lucky (or unlucky) day. No idea how a wire brush bristle ended up on the freshly painted/installed head, but there it was. Hence forth I will vacuum those depressions before removing spark plugs. (Should have reinstalled the plug before messing with it in the first place).

[PeterCrespin]

Decarbonising is easy just use a blunt chisel or similar tool to get the crusty stuff off, take great care with the pistons and head which are aluminium and easily scratched, use fine emery paper after that. Make sure you blow out the cylinders with compressed air well.

I would never use mineral abrasives on engine internals, especially soft metals. There are safer alternatives available. The only exception is valve paste (which is used on hard ferrous parts, not alloy). Even there, clean up after each valve with a succession of one-wipe disposable tissues.

[jeremybarnes]

Hello all, quick update: I confess that I took the easy way out...

I reasoned that it was worth trying to put the stud back in the block and torque it all down properly, and see what happened. I figured that, worst case, if I had a gasket leak, I'd have to pull the head off anyway, but if I didn't, I'd be in the money. So I drained all the coolant out the rad and the block, dried out the hole and ran the new stud in with the double-nut trick (it went in nearly three turns by hand, so no worries about the block being stripped -- all the damage was on the old stud -- and then another two or so with the double-nut tighten). It went in deep enough to put the lifting strap on the top and the acorn nut above that.

No issues at all, torqued it all down, held breath and started it up.

Perfect, no issues -- no smoke out the back, no water contamination in the oil on the dipstick or in the oil cap. Idled for 30 mins in the garage with the fan coming on and off, and never an issue of overheating. Think I dodged a bullet, so am going to buy a lottery ticket today...

Thanks to all of you for your advice, on to the next project!

Jeremy.

[politeperson]

Jeremy, this is excellent news.

Fortune favours the brave. Sometimes.

James

[abowie]

Good outcome.

[PeterCrespin]

Well done. I saw pictures once of giant cotton buds about a foot long, which would have beed ideal for drying out the blind stud hole. I've never seen them for sale though.