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2004 Discovery II SE-7
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Discussion Starter · #1 ·
I'll start off with the question, has anyone ever heard of a bolt breaking like this? In an aluminum Rover block no less!

After replacing 3 sets of threads on my RH cylinder bank (cause of my HG failure) I wasn't exactly in the mood to pull the presumably fine LH head. Of course I decided since I was in there I should... Here's what I'm looking at now
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I'm missing about 1-1/2 threads off the bolt on the right. I have never seen a bolt shear like this before. I pulled the head right before work so I didn't notice this until I went to run it through the parts washer since the heads were excessively sludgy.

The car is @home in the garage so I can't 100% confirm the tip is in the block, but when I was hitting the holes with compressed air I remember thinking the bottom of one looked like it was plugged with something not aluminum.
 

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2001 & 2004 Discovery Series II SE7, with AND without SAI
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Yeah - you shouldn't use those bolts (not saying YOU did). They suck. They stretch. They break. Just go with ARP studs.

To answer your question, I'd bet money that broken piece is in there. ;)
 

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2004 Discovery II SE-7
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Discussion Starter · #3 ·
Well I had already opted to go with the stretch bolts again. I heard both sides of the argument but without any firsthand experience stuck with the OEM. If I get a chance tonight I'll update.
 

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2004 Discovery II SE-7
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Discussion Starter · #4 ·
With my luck I wasn't really expecting a different result. I taped the depth of a standard bolt hole on this 1/4 extension. The tip is certainly stuck in the block.

Problem hole:
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Standard hole:
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Of course getting light down that hole for a good picture is impossible but you can tell it's not aluminum down there.
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Guess I'll try my best to drill+Easy out the tip, break the easy out in there and hate myself... I have a 100% success rate with easy outs @ work, but a 0% rate at home.
Debating if I should drill it and throw a Timesert in there like I did to repair the other side.
 

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2002 Land Rover Discovery 2
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227 Posts
Damn, bummer man. I definitely sympathize, it sucks to do a little extra work because you know you should, only to find out it’s a much bigger job than you thought.

Easy out is the route I would go, if that fails you can try a long drill bit and drill a small hole in what’s left of the bolt so that the east out has something to grab on to. Base on your pictures of the bolts, it doesn’t look like there’s a whole lot of bolt left to get out which will make things harder.
 

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2004 Discovery II SE-7
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Discussion Starter · #7 ·
I work in a small engine shop and was brought up as a car enthusiast. I trust my odds and experience on most things.
That said the current game plan is:

1- Filled the hole with Free penetrating oil (stuff is amazing

2- Borrow the boss's Snap-on reverse threaded drill bits and easy out set since he offered. They're hopefully stronger than my Craftsman set

3- Succeed with that approach or atleast stop before I break a tip off down there.

4- Pending the easy out failing drill out the threads and bolt tip all together and install a Timesert. I had to install 3 on my RH cylinders and that worked well.


I'm hoping that it was a manufacturing flaw in the bolt because there's no logical way a 7/16 bolt should snap on 1.5 threads in soft aluminum. Also since it snapped in the threaded section the threads may not have stretched so it might not destroy the threads coming out.

Fingers crossed
 

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2004 Discovery II SE-7
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Discussion Starter · #8 ·
I guess I should clarify a bit of history on the D2 and why it's in this state. This is a rescue with about 145,***mi. I bought it with the blown HG knowing the gremlins of this engine. I've also got experience working on my father's 89 RRC that he's had since 1997.

A man bought this for his 16y.o. daughter. It already had the lift but he threw a typical tune-up at it + new hoses, headliner, running boards, steering shaft, and a few other oddities. I have no concrete knowledge of the history beforehand. 500 miles go by and the truck pops the RH head gasket. He has a shop diagnose it but decides to list it locally before it goes to the graveyard.

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I decide this is in much better shape than a D2 I picked up for $500 and step in. I was fully expecting a rebuild, having to pin liners, or swap out of the other D2 but when I pulled the head someone had already had the engine machined with Top hats installed and Victor Reinz composite gaskets, what failed where the threads I'm the block. (Pic from my other post)
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At that point I had the failed HG replaced. I know the engine has been seriously worked on, but the heads had 1/8" and over of sludge buildup and the valley pan wasn't much better. I have to assume with that kind of buildup it's been atleast 50,000mi since the engine was pulled (no history on that)
Still really sludgy after a light scrub
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I figured the safe thing to do since these HG seem to have a 60k lifespan was clean both heads and do the HG.
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That brings everything up to speed to where I'm at now. I don't regret pulling the LH head, I just have never in all my projects ever seen any bolt shear in the manner that this one did. This was always going to be a pita project but I signed up for that because I think it's fun for some reason.

I'll post an update on how it goes once my little guy is with his mom for the weekend and I get some time to throw at it. 👍🏼
 

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2001 & 2004 Discovery Series II SE7, with AND without SAI
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That brings everything up to speed to where I'm at now. I don't regret pulling the LH head, I just have never in all my projects ever seen any bolt shear in the manner that this one did. This was always going to be a pita project but I signed up for that because I think it's fun for some reason.
First time I did a HG job the exact thing happened to me. I sprayed PB Blaster down in there and used an extractor. Took a bit of time but wasn't so bad I was throwing tools - just cursing some.

I've used studs and I've used the bolts. I used to swear by bolts and the Rave but as of late have leaned towards studs. ARP updated their procedure and I've never had one snap on me. As stated initially though, I can't say the same for bolts.
 

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Here's a maybe out-of-the box idea about the piece of the old head bolt still in the block. Why not leave it there?

It seems like a lot of work to remove the fragment. How about cutting off just enough of one of the new stretch bolts before installing for it to stop short of the fragment when tightened to spec? Would that little length of just one bolt on make enough difference to result in a failure?

I'm certainly no engineer, but if I were in your position this is what I'd do.
 

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2004 Discovery II SE-7
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Discussion Starter · #12 ·
Here's a maybe out-of-the box idea about the piece of the old head bolt still in the block. Why not leave it there?

It seems like a lot of work to remove the fragment. How about cutting off just enough of one of the new stretch bolts before installing for it to stop short of the fragment when tightened to spec? Would that little length of just one bolt on make enough difference to result in a failure?

I'm certainly no engineer, but if I were in your position this is what I'd do.
It's a tempting idea. I have access to a nice belt sander that would do the trick too. I would just feel better getting it out.
 

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Discussion Starter · #14 ·
It was The most anti-climatic moment of my life... miracle's really do happen. The hole is cleared and the threads intact.
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Soaked in the pictured penetrating oil for just over 48 hrs (stuff is amazing) and it came out like butter. Playing with camera settings unsuccessfully for 10 minutes to get a pic down the hole was the longest part of the whole ordeal.

Back to re-assembly and sludge removal (y)
 

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Discussion Starter · #15 ·
Got the valley cleaned out as much as my sanity will permit.
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Also found stampings and the overheat plug from the company that did the rebuild the first time.
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I'd love to find out who did the machine work the first time. Maybe That SC, NY could be a shop in New York since I bought the car in New Jersey... Or it might be factory. Anyway not much progress today, the neighbor stopped by for a 3 hour chat shortly after I started working.
 

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Discussion Starter · #18 ·
And here we go again. I guess that bolt has failed because the threads were pulling out on the driver's side too :confused:
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This one also didn't make it much past 50 ft lb. I made sure the rest could hold at least 75 before calling it a night.
Guess I'm ordering a stud kit tomorrow, should I also order another head gasket? These don't look like they get crushed when the head is torqued down but I'm not sure.

Sorry if the earlier pic was misleading, you can see the head bolts are sticking up if you zoom in. I didn't want to splash the gunk from the valley into the cylinders.
 

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2003 Discovery 2 SE7
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And here we go again. I guess that bolt has failed because the threads were pulling out on the driver's side too :confused:
View attachment 95013

This one also didn't make it much past 50 ft lb. I made sure the rest could hold at least 75 before calling it a night.
Guess I'm ordering a stud kit tomorrow, should I also order another head gasket? These don't look like they get crushed when the head is torqued down but I'm not sure.

Sorry if the earlier pic was misleading, you can see the head bolts are sticking up if you zoom in. I didn't want to splash the gunk from the valley into the cylinders.
I'd get a new gasket just to be safe. Would hate to do all that work and have it not seal right. The question if you go for studs, will you do studs in the other side, and will the rest of the holes take it? Food for thought
 

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Discussion Starter · #20 · (Edited)
I'd get a new gasket just to be safe. Would hate to do all that work and have it not seal right. The question if you go for studs, will you do studs in the other side, and will the rest of the holes take it? Food for thought
I did think about that. I'm pretty sure they could handle it, I wasn't sure about pulling the bolts out and replacing them though since everything seems ok.

Edit: as much as I want to get this back together and hear her run I probably will end up doing the studs on both sides. In the meantime I'll try to drop the pan/ timing covers today and get that cleaned out.
 
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