Sunday, April 18, 2010

The last word on Land Rover liner failures - I hope!

Note:  This story was written a few years ago, but it's even more true today.  Robison Service is building 4.0, 4.6, and oversize Land Rover engines using the latest flanged liner technology.  Call us at 413-785-1665 or write robisosn at robisonservice.com if you'd like to talk about YOUR engine project.

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I have written several articles over the years, describing the liner problems in Land Rover V8 engines. No matter what I write, the damn engines continue to fail. And we’re seeing more and more of a pattern. These engines are, as best I can tell, failing more frequently than before, especially in the last of the Discovery II rigs. Where earlier motors tended to fail on end cylinders, these motors are blowing out the middle cylinders. That led us to wonder . . . is there a new problem in these late engines?

Last week we decided to find out.

We just got a new CO2 laser up here, and our machinist Steve Dutcher was looking for some action on a lazy Friday afternoon. Some people would go fishing, or even weasel hunting, but Steve had other ideas. He cut a Land Rover engine block in half, just because it was there.

When he did, we finally got some hard answers to what’s going wrong in these motors.

Let’s begin by looking at a brand new Land Rover short block. You might call this the “pre-failure” picture:



In this shot you see the aluminum block, with steel liners, and aluminum pistons. As you can see, the steel liners are tapered at the top, sort of like you’d bore a countersink hole if the engine block were a piece of wood. . . .



Now lets jump to the late model block Steve cut in half. He removed the liners before cutting this block right through the middle of the third cylinder bank. Check it out:



This block had a middle cylinder failure. There was no visible problem with the liner but it failed a pressure test on the middle cylinder. When we took the liner out, we found the crack you see circled here. Take note of what a subtle defect this is . . . you can barely even see the crack, but it’s enough to kill the motor. Here’s a closeup of the 1/4 inch crack that cooked this block.



The block cracked from the liner wall into the coolant jacket from the stress of the head bolt. Here’s a shot of the deck that shows that relationship. In fact, if you look close, you can see how the depth of the crack corresponds to the depth the head bolt is threaded into.



Here's a closer view, with my finger for perspective. The blue circled crack is visible to the left of my fingernail



Here’s another interesting shot. In this image you can see the step that prevents the liner from sliding down into the crankcase on these newer motors. In this design, the liner can’t actually move more than a few thousandths of an inch unless they failed to seat it against the step at the factory. What does that mean? It means the stories of "slipped liners" in these newer engines are probably incorrect. The issue is not movement of the liner (which can't happen in this example) but a failure of the block wall behind the liner.



This shot shows that post-2000 model year liners can’t move very much at all but the engines fail anyway. What gives? A little bit of thought gave us some answers.

The liner is tapered at the top where it meets the head and head gasket. For that reason there is no gas or pressure tight seal between the liner and the block. Therefore, when the cylinder fires, some combustion gas gets behind the liner. If there’s a crack back there, out it goes and you know what happens next.

Your coolant gets displaced by superhot combustion gases, the engine temperature skyrockets, and in the blink of an eye, your Rover is assuming the British Position on the back of a tow truck. And you are facing a ten thousand dollar repair bill.

How do these failures happen? It sure looks like the stress from the head bolts is causing the blocks to crack. I don’t know why this is happening now; the aluminum may be more brittle, or the head bolts may be stiffer. Perhaps longer or shorter bolts would help.

Now that we know what’s happening, it’s clear that top hat liners will fix this problem once and for all, even in an engine with cracks in the aluminum. The flanges on top of the liner will seal tight against the head gasket, preventing any combustion gas from getting between the liner and the block and blowing things up.

This picture shows the difference. The left cylinder has the original liner. The right cylinder has a top hat liner, which cannot move in the block. In addition, the head gasket now seals against the liner for a firmer and more positive combustion seal.



Why doesn’t Land Rover use flanged liners? My guess is, they cost a few dollars more and carmakers are notoriously cheap. It’s also possible that there’s an issue with the steel liner expanding at a different rate than the aluminum block and heads.

How about the engines that rap at idle? I’ve had several late model Discos at the shop with noise complaints. In two cases, dealers told the drivers they had noise from liners moving up and down, and they suggested the motor was about to fail as a result. One dealer actually got the motor hot and heard it rap, at which time he sprayed the side of the block with a hose and the rap went away. He told the customer that was evidence of liner movement.

Actually, it wasn’t. These photos make it pretty clear that late model liners have nowhere to move. The hose test simply showed that the noise went away when the engine block was cooled – in other words, the noise was triggered by thermal expansion.

Steve and I sorted that noise question out on another engine a few months back. On that motor – which had exactly the same hot rap – we found the piston skirts had collapsed in about ten thousandths of an inch. That was enough to make them rock when they got hot, and they rapped good and loud.

On that engine we expanded the piston skirts and refitted the pistons. No more rap. But did that repair need to be done? Loose piston skirts would not lead to a failure. I’ll bet that motor would have run 25,000 miles with that rap, maybe a lot longer. In any case, new pistons are the fix. Liners are not involved at all, unless the block were to crack when the head bolts were cinched down one more time . . .

While were talking noises . . we saw a few engines whose secondary air valves had failed, and they also rapped. If you didn't know better you'd swear that secondardy air rap was coming from within the motor. And we still see engines with rocker shaft issues and lifter issues where the raps will fade in and out as the parts rotate while the engine idles hot.

I’m glad we’ve finally got some positive answers about these latest failures. When we rebuild engines here, I’m thinking we need to do flanged liners in the middle cylinders, and maybe all eight cylinders. The only drawback to that is going to be cost – it’s going to make the cost of redoing an old block almost as much as the $5,000 cost of a new one. But if the flanged liners last and the factory ones fail, that’s still smart money.

Like everything else, time will tell . . .

And one more thing before I go. In October I wrote about some later blocks that failed from premature corrosion. Here's a view of the freeze plugs on this motor. As you can see, they are pretty rotted but the aluminum block itself is good. Check your freeze plugs if you do an overhaul. It would suck to lose it all for a two dollar metal disc.

33 comments:

Agatha said...

great post on the 4.6. Do you find these issues primarily in the 03-04 Discos? Do you see it in the 00-02 Range Rovers also? Is it correct that a different factory was making the 03/04 4.6 for the Disco?
Thank you.

jacpsu said...

John, thanks for your analysis and write up. It was a perfect description that even someone with limited knowledge of engines (even that is on a/c jet engines) can grasp what is going on with her car. One question...I have recently decided to bite the bullet and do a full-up (long) engine transplant (perhaps I love my discovery too much but...). The engine is coming from UK complete with top hat...do you concur that I shouldn't have any problems with sleeve slippage with this version? are there any other concerns I should have with that engine?

My Defamation Suit said...

Your comments make interesting reading. I am an Automotive Engineer and your discovery that the crack on the block being as deep as the bolt holes got me wondering - When the aluminum block cast, did the rough cast have the bolt holes already cast in place, only to be drilled and tapped at a later stage. Or were the bolt holes drilled and tapped from scratch. I can almost bet that it is the former method used in order to save on machining and tooling costs. In that case, the thin section between the hole and the surface of the cylinder would have cooled much faster rate compared to the rest of the block resulting in a crystalline structure (also weaker) of the metal. This undoubtedly would lead to premature failure at that point. A microscopic examination of this section may throw some light, but unfortunately I have no such facilities available to me.

Michael said...

I_HAVE_A_QUESTION.MY_2005_TURBODIESEL_TDI6_LR3_Landrover_WENT_THROUGH_TWO_HIGH_TIDES_IN_THE_PACIFIC_OCEAN.iT_WAS_SUBMERGED_UP_TO_MID_ENGINE_LEVEL.MY_SON_WHO_GOT_IT_STUCK_IN_THE_SAND_HAD_IT-TOWED_TO_THE_DEALER.THEY_SAT_ON_IT_FOR_6_WEEKS.WHEN_THEY_FINALLY_OPENED_IT_UP_IT_THE_ENGINE_AND_TRANS_WERE_TOTALLY_CORRODED.THEY_RECO_A_NEW_ENGINE_AND_TRANS_WITH_NO_GUARANTEE_ON_THE_ELECTRICAL_SYSTEM.MY_SENSE_IS_TO_LET_IT_GO-AND_NOT_WASTE_THE_MONEY.DOES_IT_SOUND_LIKE_NEGLIGENCE_ON_THE_DEALERS_PART_FOR_WAITING_SO_LONG_TO_OPEN_IT_UP.ANY_INPUT_WOULD_BE-APPRECIATED

John Elder Robison said...

Michael, I think that vehicle is junk. You will never see an end to electrical trouble once salt water gets into the wire harness

Jacob Lorenz said...

John, thank you for finally finding a conclusive answer to the "slipped liner" syndrome. I am swapping out my DII block with this very issue (combustion gases pushing out coolant). What do you think about using studs instead of head bolts to prevent cracking of the new block?

Ed said...

they are not tapered because they had used steel liners in the past, and as you mention the liners would thermally expand at different ratios under the law of dissimmilar ratios. It also has to do with Rover changing the surface of the liner from rough to smooth so it could be an easy press in fit on the production line.

Tom said...

John,

Ah the beauty of systematic problem solving. I love it.

Quick question on ticks in the 4.6. Are rocker arms/lifters generally an intermittent tick? You mentioned those types of ticks varying with engine temps... I've got a persistent tick that sounds like its under the VC, but then again I also hear noise near the oil pan. Hmp. Not sure.

Brilliant stuff though, keep it coming.

sheepspeeddave said...

I thought you might be interested in a post on discoweb that proves the liners (at least in the 2003 model years - and probably many more) do move - and move easily when the engine is at normal operting temperature.

The engine in the post didn't have any coolant issues - just the loud ticking that plagues soooo many Series 2 discovery's...


http://www.discoweb.org/forums/showthread.php?t=74254

nicdirect said...

I know I am late to this thread - it was passed on to me via a client of ours.
Top hats are the way to go back home in NZ we have done it since I can remember as an apprentice and thus became the standard principal. I have noticed here most people do not understand/want to spend the money and dump the vehicle - which is a shame.

Buffalo said...

Great article

Question on the "hot Rap" - my 04 Disco is quiet until it warms up, then very loudly raps at idle/gas pedal release, but is quiet under load/accelerating

After my last oil change the sound actually went away for a few days, but then slowly came back (oil level is good, using full synth)

The clues here: going away after oil change, no sound when engine is cool, and rapping only during idle/unloaded have me baffled

It has been going on for quite awhile. I expected a thrown rod, but so far I only get the noise

Does this fit the piston skirt issue?

Thanks!

John Elder Robison said...

Yes, Buffalo, that's how they sound

shivabizconn said...

nice blog.
Dev Precision Engineers is the brand that is synonymous with the export and manufacture of Engine spares and parts CYLINDER LINERS AND SLEEVES.

mbrosch said...

Interesting; mostly because i brought home a sick 2001 Disco today and have plans to heal the beast. During the trek of 18 miles I used 4 gallons of water to keep the temp under control and have convinced myself that the engine is likely blasting combustion pressure into the cooling system, but haven't gotten the heads off yet to diagnose the problem.
regarding noise: I have been a mechanic the better part of my life and I was very interested in your views regarding the noise you have experienced and evaluated in these engines. Today, when the engine was hot, I heard the unmistakable sound of lifters which had lost their prime as a result of a loss of oil viscosity. The fix is easy enough: reduce the coolent temp and the oil will be able to do it's job; but I would like to pose the following. Suppose you did, in fact, have sleeves "hammering?" it seems to me that you could drill a few holes around the bottom of the sleeve and pin the thing in place with a few tapered dowel/wedges. Nothing actually happens down there anyway except that the skirt prevent the piston (which is drilled off center) from slapping the cylinder walls.
In the old days we would knurl noisy pistons on the skirts (on the lathe), tap them back into the bores and expect an easy 30k miles life extension. When I was a BMC race mechanic at Laguna Seca, We would knurl new pistons, then reduce them to the bore size, just to give oil a place to live.
Anyway, it was great to read the musing of an actual mechanic/machinist and not just some "bolt on kid."
SO: pin he sleeve, knurl the piston, Use a bit heavier oil for the valve lifters..
Why not?

John Elder Robison said...

Mbrosch, if you refer to the photos in the article you will see the answer to your question "why not pin the sleeves in place".

The answer is that the blocks crack behind the sleeves and combustion gas gets into the coolant passages. Pinning won't help that. The second problem is that nothing seals the liner to the head gasket, and pinning won't help that either. Flanged liners are the only thing anyone has found to address those problems.

Rachel said...

Hi John, Thanks for taking the time to share your expert knowledge on this topic. I have a 2003 Disco and have had a LR V8 specialist here in Australia install a 4.6 with stepped liners in to it due to the original 4.0 having slipped liners and pressurised cooling system due to crack in block. Then 4.6 engine ran fine for 40,000kms and then developed a coolant leak from behind the liner down into the sump. The engine on liquified petroleum gas (LPG) via a Landi Renzo sequential gas injection system. The LR specialist who built the engine claim that the leak is due the block cracking behind the liner, caused by very high combustion temperatures in the cylinders due to the engine running on LPG. I have also since had the ARP head stud nuts come loose and cause a head gasket leak. Again, the mechanic is blaming the high combustion temps of the LPG as the cause of the nuts loosening.
Do you believe the LPG could be the culprit of both failures? Also, would not a properly installed stepped liner create a good enough seal so as to not allow coolant to leak from a crack down into the sump? I am interested to here an indipendant point of view. Many thanks, Russ.

John Elder Robison said...

Rachel, we have recently changed to a liner that is sealed with an o-ring at the bottom for the very reason you cite.

Alice Estman said...

fantastic publish, very informative. I ponder why the otherland rover specialist brisbane of this sector don't realize this. You should continue your writing. I am sure, you have a great readers' base already!

mkelsho said...

Hi John, you mentioned secondary air valve failure caused a rapping noise. Can you explain this in more detail? Also you mentioned rocker and lifter issues causing the rapping to fade in and out. My 2004 Disco with the secondary air system raps when hot, and also under load fading in and out. It also fades in and out at idle, and sometimes i won't hear it at all for days, and sometimes it just won't go away. I also know notice the performance is much more smooth when its not making noise. Some advice wold be great. Thank You

Kenneth said...

Hello Mr. Robison, I may have the issue with the crack behind the liner - do you think one could remove a stud and pressure test thru that hole, then if finding it leaking, pump JB Weld into the crack with the excess going around the liner? Regards, Keith

John Elder Robison said...

These cracks are only a few thousandths wide, if that. They expand under heat and pressure but in any case you are not going to force a substance as thick as JB Weld into a space like that.

So I've never tried what you say but doubt very much it would work.

Ralph Vieux said...

What great Write Up I recently Purchased an 04 Discovery II with 4.6 Engine I have the exact same Noise issue going on. What are my options? New Engine and from Where?, Rebuild the Engine? What is the quickest way to fix this issue without spending an arm and a leg?

Any Suggestions Email me Please...

Unknown said...

Hi john , I have 2000 d2 with external combustion leak out the side of head ( sounds like a cho cho train . I've narrowed down to cyl 6 , could I pull that injector and spark plug to avoid further damage to block or will that fry other components ? Just a thought ... Thanks ...

John Elder Robison said...

Continued operation with a blown head gasket will damage the block deck. Park it till it's fixed

Simon said...

Hi John.

In your spec you mention you repair any cracks found before relining the block. What method do you use for the repair?

Thanks

John Elder Robison said...

Simon, we grind into cracked areas, and fill with weld

Ross said...

Thank you for sharing your knowledge super post. My question is the same as the first poster in April 2010; I didn't see an answer: do you find failure of the block wall in 2000-2002 Range Rovers or just 2003-2004 Discos? Or another way to pose the same question: if I'm looking for a 4.6, what year/model might have most longevity without either post 2000 failure of the block or pre 2000 slipped sleeves? Many thanks!

John Elder Robison said...

Ross, the 2000-2003 Range Rover motors seem almost as problematic as the 2003-4 Discovery engines. They are better as they get older, but I can't quantify that, and as the years pass, age works against us such that a motor that might otherwise be good is now likely simply worn out.

And in the case of a worn out Land Rover V8, I don't think I would rebuild any of these engines without conversion to flanged liners.

If you asked what the most reliable motors would be, I would say the 1999-2000 4.0 engines in the Range Rover or Discovery II. And it's very hard to find good examples of either here in New England.

Unknown said...

Hi John .......great article. I have a TVR CHIMERA4.0 v8 it has a very slight rattle .....example after blipping throttle as revs die then rattle.....is this piston skirt slap or cam rattle or slipped liner?
I did like the reply from the guy who knurled the skirts to retain oil!!
Andy uk.......nealeandrew@outlook.com

notny41 said...

Hi John, I have a 1996 Disco SE and it just started making this ticking noise - my disco runs cool (never gets past halfway on my temp gauge) - are you saying this is likely not a slipped liner? https://www.youtube.com/watch?v=hBhlj3HO1Ns

Stuart Davis said...

Hi notny41 (and all)

Running a '97 3.9 on lpg with a blower - a brave and rare mix for sure - bought it recently for occasional / hobby towing and 4x 4 jaunts. Drives well and pulls hard but slight tapping noise under load - goes away when light cruise, on overrun, or idle. No coolant use or pressurisation. Too light for big end I reckon, sounds like piston slap but usually that's worse when cold and unloaded imo, so might not be this? Not lifter noise either, not a tapetty sound. Could it be this, was thinking manifold leak maybe as apparently one branch leaking can sound like a tapping type noise....

Cheers
Stuart Perth Australia

Land Rover said...

Hi mate. Presumably as motor cools coolant would be drawn into the Crack and up into the pot. So when whipping the heads off a motor with such a Crack would you see traces of coolant between liner and casting? Cheers

Les Blevins said...

Are there other engines made by other auto manufacturing companies that can be used as a replacement for a Bosh engine in a 2000 Discovery II?