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Land Rover Repair/Discovery head bolt stuck


QUESTION: I have a 1998 Discovery I with 3.9 EFI engine (36D76610C).  I am trying (first timer) to replace the blown head gasket (because of exhaust in coolant, oil and coolant leak on front, low compression in cylinder 5) .  I tear the engine down to the head now, but just cannot get any of the head bolt off despite using extended breaking bar.  The engine had overheated before.  Will the bolts get stuck and seized beyond removal?  Are there any tricks to get them off?  If there is no way to undo the stuck head bolts, does that mean the engine is condemned beyond repair?
Very frustrated.

ANSWER: Hi Kwei Kin,

head bolts are notorious for being difficult to remove.  Make sure you have thoroughly cleaned the area :  use brake cleaner (generously), brushes, even Q-tips, whatever it takes to clean those bolt heads.  Use an impact socket if you have them, 1/2 inch breaker bar and a 4 ft pipe over the breaker bar.  These bolts are nasty to remove and require some considerable effort.

One Disco owner wrote:
"The HG's looked fine, but I was somewhat concerned with how much force I needed to exert in order to remove the head bolts. Im not a slouch when it comes to strength, but breaking both sides off almost made me drop a nut. Holy shit they were on there. I dont remember track parts on my M1A1 being that hard to break loose."  

M1A1 is a military battle TANK!!

Here's a very good 'write up' of the job available for you to read:

Best of luck,

---------- FOLLOW-UP ----------

QUESTION: Thank you so much for your advice.  I did as  you said and managed to loosen some of the bolts.  But the fourth one  (counting from front) on the outer left bank is particularly stubborn, and the top starts rounding off and loosing grip.  What can I do now?

Hi Kwei Kin,

glad you are having success with those bolts.  You can file the bolt head down to the next smaller size.  Take your time, file all sides as evenly as you can. Use the target socket size as your guide and stop when you have a good fit (no slippage).  Apply some penetration oil to the bolt area, tap it a wooden handle and hammer, make sure not to damage the newly filed head. Apply penetration oil and leave it soak overnight (this might help).  The next day, clean the area completely then use brake cleaner as a final cleaning agent.  Then give it a try.

It would be better to replace the bolt that you filed once you've removed it.

For those bolts that are beyond this technique, you'll need a specialized set of socket nut extractors.  I don't think you can buy only one - here, they come in a set of 10 sizes.  The
extractor has a sharp biting socket that digs into the bolt head as it turns.

Irwin makes a nice set:

This is all I can think of for this particular situation.  

I hope this helps,

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John McInnis


Land Rover Discovery. I've had most of the common mechanical failures, altenator, water leaks, wiper failure, door/hinge problems, roof rust, floor rust, loads of electrical problems. Remember, I'm not a dealer or a mechanic, just an owner like most of you.


Owner of a Discovery. I've had many mishaps with our Disco but I still like this vehicle. Talk to a fellow LR owner instead of a dealership rep. I'm not in this for the money. I'm just an owner who wants to help others.

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