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Series III XJ-6 4.2 Liter Cylinder Head removal

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M

Michael J.

Jedi Warrior
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I have the Acorn Nuts removed and the six smaller nuts around the front of the head removed.

Penetrating oil easily sinks around all but two of the head studs, but the head will not budge.

The replacement cylinder head gasket is composite with what appear to be steel rings for the actual seal.

The head protrudes about 1 1/2 inches on each side hanging over the block. I tried a small two ton bottle jack with a small wood block pushing up against the over hang, but it will not budge. I did not have this much trouble pulling V-12 heads. Is it always this hard to remove the six cylinder head?

Is there a secret to this?
 
The problem is that the head studs sit in the engine coolant,and seeps up the stud and rust and corrodes the stud bore and bonds it to the stud can be really difficult to remove the head.Perseverance penetrating oil and a lot of pushing shoving and rocking it should begin to move,try leaving it with pressure on for a day-or more!When it does eventually come off the studs should be replaced,the last thing you want is to hear "PING"when the stud breaks as you do the last torque pull down! Good Luck
 
Be really careful removing the studs.They screw into the block near the crankshaft. Most of them can be accessed by removing "freeze" plugs. I would reccommend knocking out the plugs, and directly soaking the threads in the block, and maybe a little heat before removing them. A little time and patience spent before beats the you-know-what out of removing the block to get it drilled out by a machine shop. If you are clever and handy, make a head pulling plate. Attach the plate by the spark plug holes. (The one I have used has the metal ends of spark plugs welded to the bolts for a perfect fit)Drill and tap holes that correspond to the head studs, and evenly turn the bolts down against the studs. This will pull the head off. I know that British Parts International makes one for V12s, and it might be worth checking if they have one for 4.2s
Good Luck
 
It takes time! Keep your cool and use the penetrating oil, pull, rock, etc. Let sit try again. Use some spacers each time the head moves up to keep it from dropping. A second set of hands helps as then you can work from both ends at once. Since you should replace head bolts, you can remove them which, if they do not stick in head will help.
 
As several have mentioned, it takes time. There are lots of posts about this on Jaglovers.org. I read one post where one member kept pressure on with a couple of jacks for 3 weeks before it finally popped loose. Patience is far better than stud removal at a machine shop. Sorry, but theres just no easy way. Most of these cars are close, or past the twenty year mark, with alot of miles, so a little patience is nothing compaired to what it took to get in that condition in the first place. Good luck. Keith Hodges, 85 XJ-6, 95 SJS 2+2 Conv, 6.0 V-12.
 
It finally came loose after soaking the studs twice per day for a couple of weeks with PB Blaster and using 4 bottle jacks, two on each side, to keep it under pressure. I have it being cleaned and inspected for condition to see what parts are needed at a local shop that has done a number of Jag engines over the years.

It was almost as hard walking it up the studs to get it off.
 
Way to go. I love hearing success stories like this. Patience is the best virture there is. Congrats!. Keith
 
Late as usual... BPI did have a plate for the sixes a decade back. Likely still do. If you do this job more than once a year or intend to keep the car it's worth every penny, too.
 
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