XJ6 & XJ12 Series I, II & III 1968-1992

engine head will not come off

 
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Old 10-28-2014, 03:05 PM
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Default engine head will not come off

ok i have a 1984 xj6. i've disconnected all but 1 or 2 hoses, unscrewed all 6 of the front head bolts, both cam sprokets and all 14 of the top bolts. the head has been hooked to a lift since early september and hasnt budged at all. i know i read of a few people having to wait a week, but i don't think this thing is coming off. any ideas? i'll post a couple of pics when i can get my phone connected to my computer.
 

Last edited by rs200evo; 10-28-2014 at 03:07 PM.
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Old 10-28-2014, 03:37 PM
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Alloy heads on iron blocks have plaqued mechanics since the beginning.


I have a vague recollection of reading of a pair or more "hidden" bolts up front. From the underside?


And, reading of using one or more bottle jacks to push upwards under the manifolds


Perahps a combo of the two, pulling from above and pushing from below.


On flat head Fords,a t times, some removed all the nuts and fiored up the engine!!! Because of the OHCV, here not feasible.


And, with a bit of imagination. mebbe a manifold allowing air pressure, lots of it to be applied vis the spark plug holes. Cam removal needed to assure that allvalves are closed.




Carl
 
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Old 10-28-2014, 03:42 PM
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Originally Posted by JagCad View Post
Alloy heads on iron blocks have plaqued mechanics since the beginning.


I have a vague recollection of reading of a pair or more "hidden" bolts up front. From the underside?


And, reading of using one or more bottle jacks to push upwards under the manifolds


Perahps a combo of the two, pulling from above and pushing from below.


On flat head Fords,a t times, some removed all the nuts and fiored up the engine!!! Because of the OHCV, here not feasible.


And, with a bit of imagination. mebbe a manifold allowing air pressure, lots of it to be applied vis the spark plug holes. Cam removal needed to assure that allvalves are closed.




Carl


thanks for the reply carl. i did get the 6 hidden ones up front, unless there are more hidden ones lol. it's a half ton lift and the front wheels are almost off of the ground. i get in there with a rubber mallet and hammer away where i can. i also shake and pry where i can but nothing. thinking i'll have to take it to my local mechanic and just have him pull it off.
 
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Old 10-28-2014, 04:23 PM
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The attached pictures are how not to remove a Jag head. Mayhem and destruction. I believe there are pictures on jag-lovers.com of a jig someone made. The jig is a press/puller that forces the head off. The corrosion around the head bolts is massive. The swelling locks the head on.
 
Attached Thumbnails engine head will not come off-img_0478.jpg   engine head will not come off-img_0484.jpg  
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Old 10-28-2014, 04:27 PM
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An Image from the Jag-lovers Photo Album


Found the link to the removal jig, posted above.
 
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Old 10-28-2014, 05:34 PM
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Sorry, but have I understood correctly ?

You say you have unscrewed all of the 14 head studs, and the smaller studs at the front. Does this mean just removing the nuts, or are all the studs removed ? Reason I ask is because it is corrosion between the studs and the head that seizes the head on. The large diameter studs are mostly about 12" long, and can be removed with a stud extractor, but are then scrap. The two rears are short and one is a dowel stud to locate the head on the block.

When I took mine out way back in 1992, I bought a new set. I had no trouble shifting the head. Failure to keep the anti-freeze in the coolant causes loads of trouble because it also contains corrosion inhibitors.

I assume the camshafts are now totally disconnected from the drive sprockets, which are now fixed onto the temporary carriers.
 
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Old 10-28-2014, 06:10 PM
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Originally Posted by Fraser Mitchell View Post
Sorry, but have I understood correctly ?

You say you have unscrewed all of the 14 head studs, and the smaller studs at the front. Does this mean just removing the nuts, or are all the studs removed ? Reason I ask is because it is corrosion between the studs and the head that seizes the head on. The large diameter studs are mostly about 12" long, and can be removed with a stud extractor, but are then scrap. The two rears are short and one is a dowel stud to locate the head on the block.

When I took mine out way back in 1992, I bought a new set. I had no trouble shifting the head. Failure to keep the anti-freeze in the coolant causes loads of trouble because it also contains corrosion inhibitors.

I assume the camshafts are now totally disconnected from the drive sprockets, which are now fixed onto the temporary carriers.

I removed the nuts, but the studs are still in place. i was hoping to keep them intact because removing them would ruin them and i also risk snapping them. from working on it today i believe it is the studs that are holding it on to the block. yes the cams are disconnected, that was also a journey. so would you recommend i go with the stud extractor? i don't see any other way i can go from here.
 
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Old 10-28-2014, 07:25 PM
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some images. don't know if they are of any use
 
Attached Thumbnails engine head will not come off-1028141423-00.jpg   engine head will not come off-1028141427-00.jpg  
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Old 10-28-2014, 08:06 PM
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Pop on over to the XJS forum and check out Kirby Palm's XJS Book in the "how to" quick links and check out the ideas on head removal....this is for the V12 motors but a lot of this is probably pertinent to the 4.2 I6.

Here is a quote on one method, from the book, (I've used a similar method on 19th century antique telescope refurbishments back in the 70's), this is what I will try first when the time comes:-

Loren Lingren sends this tip: “With all the nuts removed, try to wiggle the end of each stud by hand. The stuck ones
will not move. Begin soaking each stud with a good penetrating oil. Get several 7/16 SAE nuts (Don’t use the head
nuts unless you have extras) and an air hammer with a tie rod tool attachment. The idea is to vibrate the studs with the
air hammer, protecting the threads with the disposable nuts. Caution must be used not to bend the studs or gouge the
head surface. Continue to apply penetrant as work is done. As the studs loosen, the penetrant will disappear down
between the head and stud. I have used this procedure successfully for several years in removing even the most stubborn
heads, 6 or 12 cyl, without any expensive side effects.”

You should only try removing the long studs as a last resort... I think,even without any snapping, you will have crud in the blind holes in the block....a long reach tap will be needed to clean out the threaded blind holes.

Hope this helps,

Rob.
2006 X Type Sport Wagon.
1987 XJ6 Daily driver.
1994 XJS 6.0 V12 Convertible.
 

Last edited by 1100me; 10-28-2014 at 08:08 PM.
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Old 10-28-2014, 08:40 PM
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If you don't wanna remove the studs.......


The head is wider then the block so, at the mating surface, you can see a ledge where the head overlaps the edge of the block. Get a small bottle jack or two ($8.99 cheapies will do) and, placing it/them under the cylinder head at the overlap ledge, push the head off the studs.

Positioning the jacks will take a little imagination and you'll have to move them a few times so the head lifts moves upward evenly.

It works

Cheers
DD
 
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Old 10-29-2014, 12:50 AM
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ok, i will try both of these methods. thanks for all of the help guys
 
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Old 10-29-2014, 08:04 AM
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I got a good (but sympathetic) cackle when I saw this thread title last night. The head of the XJ series almost indeed 'won't come off' 9/10 times. It took my father and I about 3 weekends to get mine pulled free, and after that the machinist had to bake it back into true.

Our first attempt was the tried-true 'leave it hang overnight with a crapton of wd40 in it' method. No joy. Then I contacted Dave at everyday XJ to see what his thoughts were. Bottle jacks were the recommendation, and they did work.

The bottle Jack method does work best with 2 people (one on either side) keeping the jacks 'even'. Then apply pressure and liberally spray the studs with WD.

You do have to remove a pile of stuff (including the manifold - which itself tends to stick) from the engine.
 
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Old 10-29-2014, 08:22 AM
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Originally Posted by Calhale View Post
You do have to remove a pile of stuff (including the manifold - which itself tends to stick) from the engine.

Glad you mentioned this.

They do stick, yes! If you take the head off with the inlet manifold attached you will have a doubly difficult time separating the two.

No matter method is used to remove the head, remove the inlet manifold first while the head is still firmly in place!

Cheers
DD
 

Last edited by Doug; 10-29-2014 at 08:40 AM.
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Old 10-29-2014, 08:32 AM
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I totally agree. I pulled head with manifolds attached. Not only was.it even heavier. But intake was well and truly stuck too! I ended up pulling the attaching studs (no easy task) and then whacking the crap out of it with a deadblow hammer! It finally came off but it would have been much easier while head was still attached!!
 
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Old 10-29-2014, 11:28 AM
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There are better corrosion dissolvers than old standby WD 40. It is primarily a dessicant rather than a penetrant. although, I've noted that the makers of WD 40 nmow offer a penetrant under the same label..


And, from way back, some older mechanics swore by molten candle wax dripped around the stud!!


Carl
 
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Old 11-03-2014, 06:36 AM
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Is it off????
 
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Old 11-04-2014, 10:05 PM
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Originally Posted by Darrenmb View Post
Is it off????
I just got back from working on it. I ended up pulling the studs and it fought me every step. While i was pulling one of the front studs the head popped up and now it won't go back down in the rear. So i don't have enough thread to clamp onto and the head won't slide off when i hook the lift to it lol. So i would recommend keeping a couple of head nuts on during the process to keep it level until you're ready to pull it off. The two at each end are not a problem and really don't need to be pulled but the middle ten are a different story. I'm going back again sunday so i'm sure i'll finish it off then.
 
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Old 11-05-2014, 09:24 AM
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I heard before that these cilinder heads can stick pretty bad. to the point where you lift your car by the cilinder head.

good luck though!
 
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Old 11-06-2014, 04:17 PM
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Hi rs200evo

If the head was stuck that bad then it is almost guaranteed the head studs will be shot and need replacing. When I rebuilt my engine in 1992/3 I got a friend of mine to make up a tap with a very long shank so I could clear out the tapped holes. However to do this properly, you really do need to remove all the core plugs and flush out the block. When this has been done, you should vacuum out, (using a small diameter tube) each stud hole before final clearance with your special tap tool. Use some grease to ensure the crud sticks onto it and is removed. Making sure the coolant passages are clear, and the stud holes clear is not a job to be rushed. Tear-**** mechanics have no role in a Jaguar workshop !! Memoery fades, but I think the two studs at the rear of the block are short and will need no special attention as they are dry, unlike the long studs that are constantly bathed in coolant, like the V12's.
 
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Old 11-06-2014, 08:41 PM
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Originally Posted by Wilfred88 View Post
I heard before that these cilinder heads can stick pretty bad. to the point where you lift your car by the cilinder head.

good luck though!
Yep, my XJ6 hung with the front wheels off the ground for about 3 days. Didn't budge but 3/4th of an inch. After that: bottle jacks.
 

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