Eventually it gave up the struggle.
As mentioned earlier, even with a bottle jack giving 1 ton between crankshaft and front of head, plus full pressure from a head removal tool on all tappet studs,it did not move.
It took the jack and a lot of persuasion from a very big hammer to shift it 5mm at the front end.
From then on it was tool plus jack to get it up to clear about 80% of the main studs.
There would have been no hope of getting the head off if the engine was in the car.
The tool ran out of puff at the 80% mark. From then on it was jack at front plus a 4 foot length of solid timber levering the back end.
It would move a few mm at a time so I could drive in a wooden wedge to hold it.
That final 20% still took a major effort.
If I was in U.S.A or U.K it probably would not be worth starting with such an engine that has not had much TLC by the look of it.
There are plenty of sources for used HE V12s which would give more choice.
Down this end of the world they are rare as hen’s teeth.
Just have to persevere with this engine.
Hopefully the A head is no worse to lift off.
The head and block look as if not much inhibitor ever used in the coolant.
In spite of this there is barely a ridge in any of the bores, I can just feel maybe 2 or 3 thou at most.
Anybody seen a worse one ?
Richard
Wow… That is REALLY gunked up!! What sort of shape was the head surface in??
What was providing all the resistance to removal…is it corrosion on the studs increasing the diameter a bit so the head has to shear off the corrosion…???
Matt
I guess it was corrosion on the studs giving the nightmare Matt.
Unbelievable how tight the grip.
When I rebuilt the original pre HE V12 from the coupe it was fairly easy (
as V12s go ) to get the heads off.
No special tools, just wooden block against head and a big hammer on the
block.
Those studs were in pretty good shape.
The HE V12 I rebuilt for the coupe had heads off when I bought it.
I actually ran a slightly larger drill down the main stud holes to clean
them out, and make any removal just a bit easier in the future.
That engine was a bit dirty but nowhere as dirty as this one.
It looks like it used tar slurry for oil.
​The head surface is dirty, had no time to clean it up but at first glance
no corrosion anywhere vital.​
Richard Dowling, Melbourne, Australia. 1979 coupe + HE V12 + manual; 1989
convertible; 2003 XJ350.
Congratulations on your perseverance! Using a slightly larger drill bit to clean the stud holes will keep this problem from manifesting itself again, though once rebuilt, you should not have to pull a head again! Keep up the good work!
Yes. Full jacking force on all the tappet studs AND more required.
I wondered if some heat into the head would have worked. I only had a small butane burner and attempted this using Kirby’s small jacking plates but not enough heat by a country mile.
But I do wonder if you could get the head up to 80-90 deg C with one or two burner torches would it come off.
There’s gotta be a way to reliably get these heads off in the engine bay.
Matt
Heating the whole head, either in or out of the car, would not be easy.
If you only heat the head, and not the block, the head will expand and that might trap the studs even more.
I doubt heat in itself will help move the crud around the studs which is the real problem.
I started on the A head today and the tool has just lifted the rear of the head by maybe 2mm, mostly on the outside.
On the B head the outside also lifted much easier than the inside.
In any event, it was the front end of the head which proved most stubborn.
Those studs are fixed into the block really tight.
I tried removing one once with a stud extractor that grips the stud better than a couple of nuts locked together.
That technique did not work out too well.
The extractor bites into the shank of the stud and it looked like the bite mark would be very deep before the stud moved, and possibly ruin the stud.
It would be no surprise if the studs were set with Loctite.
Lots of heat, say 250deg C, will weaken the Loctite considerably.
Two nuts locked on the stud with head in place will not overcome that Loctite plus crud.
Be nice if it could be done of course.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
9
I guess it was corrosion on the studs giving the nightmare Matt.
Unbelievable how tight the grip.
Three suggestions from the distant past:
Use modelling clay to form little dams around each stud hole and then
pour in something. One idea was Coca-Cola, but some argued there were
better substances for the job.
Fab something akin to a hole saw that fits snugly around the stud and can
be used to clean out the hole surrounding the stud. You could arguably
make something out of a tin can. Fiddly, but arguably less fiddly than
methods that don’t work!
Screw some scrap nuts onto the ends of the studs and attack them with
an impact chisel. Whole lotta vibration on the stud. The idea is to crumble
up the crud so it falls out.
I cut up pieces of plastic conduit tube and stuck them around studs with silicon.
Poured in various penetrants.
Some tubes held penetrant, obviously 100% blocked.
Penetrant probably never did penetrate.
Others had at least a pinhole, penetrant leaked down and out.
Result: More or less zero.
Many years ago had an old pre HE donated to gather some accessory parts.
Tried the thin walled cutter idea to go around studs.
If it was funded by NASA no doubt one day it could be done.
Otherwise forget it.
Never tried the air chisel idea.
Looking at the studs on this engine I kind of think it would be a fond hope.
My guess is that at times 2 tons of force was put on the B head and it still needed a lot of hammering to move it.
I wonder if all the suggestions about using various types of penetrating fluid on head studs has ever worked.
With this engine no joy at all.
I don’t have the engine in front of me right now. When you look at it the main studs are something like 5" into the head and have a clearance of, say, 0.1".
First problem is if there is even a small pinhole down the stud length, the penetrating fluid just leaks down there and never gets to work on the real problem.
Second problem: If there is no leak it is a big ask that the fluid acting on a very small area at the top of the stud is going to get down even an inch, never mind 5".
Does fluid work, or is this an urban myth ?
For sure the hours spent on this V12 trying to get any useful result from any type of fluid was a waste of time. In the end lots of grunt was the solution.
I did keep putting oil on the studs as 4 hours was spent jacking up and hammering to get the B head off the block.
Did no harm, but hard to say it did much good either.
The A head is now getting attention. Using a bottle jack against the crankshaft, full tightening on the head removal tool and my burly employee swinging a big hammer we just got the front end up 2 or 3mm.
The inner rear end has not moved. That is unfortunate since there is no crankshaft or anything else to use as a jacking point. Nor is there anything on the head at that end to jack up.
The outer edge of the head has moved all along its length. It seems the really tight studs are at the higher inner end of the head. That inner side of the head collects most of the crud.
Richard, l have had some success removing stubborn heads by see sawing the lift process rather than just a straight out lift.
Best explained as apply lifting force at one end of head, then other working in very small steps. If movement comes to a halt work at alternating lifting and lowering at each end to allow the threads to work away at the compacted crap around the studs.
​Very true,
It is a long head and you have to make sure it comes up square​ to avoid
jamming the studs.
That is the theory. In practice when some studs are free and easy, and
others tight as the
proverbial fish’s … it is a battle.
Richard Dowling, Melbourne, Australia. 1979 coupe + HE V12 + manual; 1989
convertible; 2003 XJ350.
Richard
How about this for a suggestion.
Pull the head back down onto the block
Remove the cams so all the valves are closed.
Put some starter fluid …or even petrol into,the cylinders.
Remove all the head nuts
Get behind something solid.
Fire all the spark plugs
See what happens…
Could be worth a shot as a last resort…big shock loading.???
Matt
Hi Richard
The only thing no one has mentioned is the advantage of knocking the head back DOWN periodically? this will expose some of the crap in the threads at the top of the studs. Clean it off introduced more penetrating fluid i.e. Duck oil, Plus gas or similar.This does help the penetrating fluid to go down the studs. A solid steel plate of about 1" thick steel is the best type of puller.
Mine also has high tensile bolts the go into the tappet block stud holes.ive had tappets studs shear and fly past me ear at a high rattle of knots in the past!studs were never lock tires into the block. Unfortunately they were put in DRY from a desoutter multi stud feed ,massive air driven stud installer on the transfer line at Jag Radford works.
Knocking the head back down at times is a reasonable idea, Nigel.
This morning spent 2 hours and managed to get the rear inner of A head up 5mm.
To do this putting full torque on the tappet studs, and hitting the rear of the head with a very big hammer.
Luckily there is a projection at the rear of the head which allows getting in glancing blows to shock the head without damaging a vital surface.
Twice I knocked the head back down but it does not do much when the head is only up 5mm anyway.
The trouble is that the outside of the head comes up very easily which means the head is not coming up square, thus tending to bind on the studs.
I can see another 6 or 7 hours work to get the head off, pretty much the same as the A head.
I will not be amused if I find after all this work there is a really major issue inside the block making this engine scrap.
Hi Richard
Don’t know if you’ve got the second head off yet? If you can work out which studs are the tight ones, heat the head around the stud holes not too much but I use an oxy acetelene torch on them! The head will have to be skimmed anyway even if it’s reusable.
So no harm done. This is particularly helpful when it’s the inner studs that are tight.
Well Nigel,
Did not take long to find the tight studs.
Either 2 or 3 in the middle of the 7 along the top inside of the head.
This morning started with a 5mm gap all around the top edge of the head,
The lower outer edge appears less jammed and had maybe 8 or 9mm gap.
Using a jack on the front, and hammer and crowbar at the back on projections that can take a bit of grunt, after 1 and 1/2 hours work we have 14mm gap along top edge.
To get the 14mm required alternate work on the front then back of the head, in a see-saw motion, to gradually ease the head up off those 2 or 3 really sticky studs.
There is no way the head lifting plate can give much help, the tappet studs would either break or strip the threads in the head before the head moved a thou.
With 14mm gap I can get a long crowbar into it plus alloy packing pieces to protect critical surfaces. I think another 4 or 5 hours work should get the head off. This A head is even tighter than the B head which was itself a royal PIA to lift off.
I seriously doubt heating anything on the head will do any good. Aluminium is a good heat conductor, you cannot heat a local area around a stud. Even if you could it would not dissolve or move the corrosion products any better than pure force and impact on the head.
Once the heads are cleaned up I will bolt the tappet block and camshaft back in position. If the camshaft spins easily I will know the head is not warped. Then provided there is no damage to sealing surfaces there is no point in skimming the head. I would like to drop the head on a surface plate with engineer’s blue to double check the sealing surfaces are flat. Not sure if I know anybody with a surface plate, and the way manufacturing and engineering industries are shutting up shop it might be hard to find anybody who even knows what a surface plate is.
Of course the other possible nightmare is dropped valve seats. I will know the answer to that when I have the valves out of the heads. Still, on the bright side easy to fix the dropped seats at this stage with the heads off.
