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Discussion Starter #1
Land Rover Discovery II overheating engine failure is getting more and more common around here. The "traditional explanation" is that the liners shift within the block and somehow combustion gases get into the coolant. In the early days I know that was true because I saw 1990s engines where the liners dropped slightly into the block. However, LR supposedly fixed that issue, yet the failures continued. In fact, the engines in the last Discovery II models seem to fail at a higher rate than the 1990s models.

I have also seen liner movement blamed for engine noises. Is that accurate?

We recently cut a 2003 Land Rover Discovery engine in half to determine why it failed from overheating. Are the "slipped liners" real or not? I have the writeup and pictures on my car blog at http://robisonservice.blogspot.com
 

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2002-2005 Range Rover MkIII / L322
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Re: Liner failures in Land Rover V8 engines - what's happening?

A thought provoking article, John. Can you cut that block through the bolt hole for a further check?

Also, may I publish that article in the LROC Sydney (Australia) newsletter, please? I am the LROC News editoir.

Regards

Ron Beckett (with a top-hatted V8 block)
 

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Discussion Starter #3
Re: Liner failures in Land Rover V8 engines - what's happening?

We don't have to cut the block through the bolt hole. We have a dedicated pressure test fixture for these blocks, and we can blow air through the crack you see. We can gauge the crack line as the end point of the head bolt. What more is there to ask?

The question of why they crack there remains. What we are seeing lately is more and more of the mid-cylinder failures. Would longer bolts help prevent it? I don't know. Top hat liners are a repair but is there a preventative measure? That is the big question.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

Re feeling the leakage, fair enough. However, I was thinking that perhaps you could see how and from exactly where the failure is occurring.

I wonder if it is related to thermal stress fatiguing the metal where the thread ends then the metal failing upwards. (Of course, one could wonder about the cylinder block thickness in the 3.9/4.0/4.2/4.6 engines.)

Is there a relationship with the change from conventional bolts torqued to a specified tension in earlier engines to the use of bolts tiightened with torque plus angle.

Except for the difficulty in removing cylinder heads, would the use of studs with thread sealant work in the short term?

Just ideas being tossed around.
 

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Discussion Starter #5
Re: Liner failures in Land Rover V8 engines - what's happening?

Ron, you can see it cracked through from the bolt hole right now. I do wonder about the change to torque to yield bolts, and whether they overstress the blocks.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

If you want the truth about what is going on, maybe call Richard Turner at Turner Engineering. :think:
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

Hi John,

do you think ARP head studs would help or worsen the situation ?

very nice article, btw.

regards,

N.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

Hey, I'm just suggesting a call to Turner Engineering. That's all. You need to talk to someone who has years of experience with the RV8, not the 99.9% of us on the forum who have never cut their engine block in half.

I'd pay for the call. I'd like an answer on this.
 

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Discussion Starter #10
Re: Liner failures in Land Rover V8 engines - what's happening?

Rich, the tone of your first post suggested that the Turner folks had an answer that I was missing out on over here. I apologize if I misread you. Here at Robison Service we've been overhauling these V8 motors for 20+ years; as long as they've been selling them in this country. Given that background, I'd like to think our insights are more than idle speculation but we certainly don't have all the answeres here - just more questions. I have read Turner's material and we've talked to them and the RPI and other folks on your side of the pond on several occasions. The idea that the blocks crack behind the liners is indeed something they have talked about before. However, I've not heard any new revelations about the underlying cause or preventative fix.

I know they fit flanged liners on their motors over there and this is one reason why. My own machinist says that's how these engines should have been built in the first place. The problem is, the liner fix costs almost as much as a replacement short block (near $4,000 US when including other short block rebuild costs) So is there something we can do to prevent failure?

As I said, I have never heard any talk about the cause. And I certainly have not heard any talk about why the newer engines seem more vulnerable as the bore and dimensions have not changed.

Best wishes
John
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

A chap I was talking with has wondered if the holes are fully threaded with a botttoming tap. If not, are the head bolts too long for the fully threaded section?

He's a member here but hasn't been on for a long time so I've asked him to join in.
 

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Discussion Starter #12
Re: Liner failures in Land Rover V8 engines - what's happening?

Ron, we talked about that but they do not appear bottomed in this particular engine. Bottoming would cause stress in the threaded hole, which would strip out. It would not cause a "pulling apart" crack like in the photo. I think these cracks come from excess torque combined with weakening of the casting after repeated thermal cycling.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

I don't have a lot of experience with the rover v8, but I would like to add that the later models used the Bosch management system and Dexcool. I wonder if one of those factors could be weakening the later engines? It might not have anything to do with it, but its just my 2 cents worth `) . Those are absolutely gorgeous Bentleys by the way.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

very nice article

just wondered though, what (in your oponion), would be the long term effect, if top hat liners were machined in, would the engine suffer again, due to the problem being the block, not the liner, or would it be ok, due to the headgasket making the seal on the top hat, therefore the combustion gases not being able to pass?
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

Great article! So does this mean the 'slipped' liner term is used incorrectly for a 4.0 or 4.6 in a p38?
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

Hi all very interesting thread and here is some information given to me over the years by some good mechanics and engineers and it is that you should never use oil to lubricate a closed thread eg:cylinder head bolts.
The reason was that if you apply to much oil and it runs down through the threads and gathers in the bottom (which it will) and then insert the bolt and tighten you are in effect in the world of Hydraulics and the pressures would greatly increase.
So could it be possible that during the machining process some cutting compounds/very light machining oil has gathered in the areas where the cylinder head bolts would go,thus creating a weak point in the block and over time it eventually cracks.

It is just a theory and i would certainly appreciate your comments.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

PAULBROM said:
It is just a theory and i would certainly appreciate your comments.
This makes sense, but I think you'd have to use an excessive amount of oil to cause this type of problem.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

Tends to confirm Mark Adams theory that the use of stretch bolts accentuated the cracking problem. He too has noted that cracking generally occurs near to a bolt hole.

The problem wasn't fixed with the latest Coscast blocks either.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

It seems my question got lost in the debate...

Since now we're pointing at the stretching bolts as the culprit, I repeat my question: would the use of head studs (like the ones ARP sells) alleviate or worsen the problem ?

thanks,

N.
 

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Re: Liner failures in Land Rover V8 engines - what's happening?

Here is an interesting article, didn't even realize it related to rovers until the end: http://www.gomog.com/allmorgan/stretchbolts.html

Wonder if the old buick v8 design rover used was designed for non-stretch bolts and the design carried over. Now that's a pretty far stretch :dance:

Here is a good link that describes the stretch and load distribution on studs vs bolts: http://www.thomasnet.com/articles/hardw ... stud-bolts


I think studs would be better suited, from the example above head bolts react to 2 forces while studs only react to 1 force. If you could eliminate all forces in that area, I'd imagine the blocks would not crack.
 
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