HG Failure

Ok, so i was just starting to get all smug about a trouble free P38 when yesterday......misfiring & a really lumpy idle. So off to see Warren @ WGB in sheffield. Spark ok to all plugs. Did a compression test on all cylinders. All getting about 175 apart from 5 & 3 getting around 75! So it sounds most probably like the HG is split between these 2 cylinders.
Looking at approx £700 for new headgasket, proper oem leads etc. Now i'm paranoid about slipped liners & dont want to go spending money fixing HG's if there is an underlying problem that will re-surface. Warren warned me that it's not always possible to detect a slipped liner until the heads are back on & running. Is there any way of detecting this? Ive never had overheating issues but have noticed a tapping / ticking sound coming from somewhere near cylinders 5 & 3. Is it worth biting the bullet & going for a top hat linere'd block?

Sounds like it's gone between the two. Strip it and check it out, if head is flat may just need a gasket. £700.00 is a lot of money for an afternoons work.

It's a tough one. A few years ago I used to have a TVR Chimaera and one day it overheated. Took it to a TVR specialist and they diagnosed that the head gasket had gone. So they took the head off, checked everything, fitted a new head gasket and guess what? Still overheating. It's rare in TVRs but yep, it was a slipped liner. So the block went off to TVR Power and had top hat liners put in it (luckily they didn't charge me for the head gasket work). So in answer to your question, yes, it is difficult to spot a slipped liner with the head off.

There are lots of articles on here on slipped liners I have my engine stripped down and in for a liner replacement to be honest if you have had no over heating or pressurisation issues I would guess and guess being the operative word at it being just a hg failure so if it was me I would spend a sat afternoon and take the heads of and have a little look if it has slipped there may well be witness marks but until you strip it noone will know

No overheating since i've owned it (7 months). First thing i did when i got her was give the cooling system a overhaul - new rad, pump, etc. Never had any pressurisation either. Just the slight tapping sound bothers me. Oh well, see what shows tomorrow.

Difficult to spot a slipped liner ??

I'd say it isn't difficult at all, not if you check your deck height (the measurement taken from the block face (the deck) to the top of the liner), even a '0' deck height will have a variance on the affected cylinder if a liner has slipped. Simply the top of the liner to the top of the block face 'the deck' you can also do this from top of liner and deck to top of piston when at top of stroke, a slipped liner will be obvious and in some cases a bad big end too. (everything needs to be suitably clean of course)

The blocks of 3.9, 4.0, 4.2 and 4.6 (not the 4.6 'Thor') are known to crack and cause leakage around the liner, check around the cylinder head bolt holes. Rover V8 gaskets seal on the deck not the liner.

Thanks BenKenobi,
Will give it a good check over this afternoon when the heads are off. Was also reading about running a pressure test on the block to show up a slipped liner although this is carried out on a cold block, i would of thought the block would need to be at normal operating temp to show anything - which is impossible? Mine is the 4.6 thor (02). I didnt realise these blocks were different from the gems?

BenKenobi said:

Difficult to spot a slipped liner ??

I'd say it isn't difficult at all, not if you check your deck height (the measurement taken from the block face (the deck) to the top of the liner), even a '0' deck height will have a variance on the affected cylinder if a liner has slipped. Simply the top of the liner to the top of the block face 'the deck' you can also do this from top of liner and deck to top of piston when at top of stroke, a slipped liner will be obvious and in some cases a bad big end too. (everything needs to be suitably clean of course)

The blocks of 3.9, 4.0, 4.2 and 4.6 (not the 4.6 'Thor') are known to crack and cause leakage around the liner, check around the cylinder head bolt holes. Rover V8 gaskets seal on the deck not the liner.

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It depends if it's slipped or cracked. This is some interesting reading JE Robison Service — the blog: The last word on Land Rover liner failures - I hope!

The blocks aren't significantly different but I have yet to hear of any such issues with a 'thor' - doesn't mean there aren't any but I have been out of the V8 scene for 15 years.

Interesting article. Also frustrating that Landrover choose to scrimp on the block design on such an expensive car! It seems all liner failures lead to pressuring & overheating which i have not experienced with mine. Would be interesting to see if anyone else on here has had a liner / block failure without these symptoms.
Also, it's strange how no engine management light has come on? You would think a miss fire would play havoc with the 02 sensors etc?

stjohnsmythe said:

It depends if it's slipped or cracked. This is some interesting reading JE Robison Service — the blog: The last word on Land Rover liner failures - I hope!

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not new news at the time however very correct,it was known in mid 90s with the 3.9s ,we chopped a few blocks up to check ,lr at the time said it was a different casting and the 200 thou wider liner fitted in a thicker aliminum bore than the 3.5 that never suffered from cracking,as it turned out none of the bloks we inspected had thicker walls but as 3.5 minus the 200 thou ,so block was weaker to start with all the blocks liners seat on a ledge not just later any that dont are manufactured badly ,and i know of a company that did fit hundreds of liners badly

jamesmartin said:

not new news at the time however very correct,it was known in mid 90s with the 3.9s ,we chopped a few blocks up to check ,lr at the time said it was a different casting and the 200 thou wider liner fitted in a thicker aliminum bore than the 3.5 that never suffered from cracking,as it turned out none of the bloks we inspected had thicker walls but as 3.5 minus the 200 thou ,so block was weaker to start with all the blocks liners seat on a ledge not just later any that dont are manufactured badly ,and i know of a company that did fit hundreds of liners badly

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LR must of known of potential issues when manufacturing. I suppose they thought if it happens outside of warranty then it wouldn't be their problem.

Thought the slipped liner could also be detected by a pressure test with the heads off?

Will try this tomorrow when heads are all off. Apparently it's not 100% reliable though as the liner should be worse when the block is at operating temp.

martynv8 said:

Will try this tomorrow when heads are all off. Apparently it's not 100% reliable though as the liner should be worse when the block is at operating temp.

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I think it will be fine. As the coolant wasn't pressurising before, etc then I don't think a liner slipped.

I'm hoping so. It was running perfectly right up until the sudden misfire. Heads will be off tomorrow so will see if anything abvious shows up. Ive spent so much time sorting out the niggly things i'm in it for the longhaul. My better half is pestering me to get an L322 but theres just something about my P38 that puts a smile on my face every time i see it on the drive....& driving it....well we all feel special in these.

martynv8 said:

I'm hoping so. It was running perfectly right up until the sudden misfire. Heads will be off tomorrow so will see if anything abvious shows up. Ive spent so much time sorting out the niggly things i'm in it for the longhaul. My better half is pestering me to get an L322 but theres just something about my P38 that puts a smile on my face every time i see it on the drive....& driving it....well we all feel special in these.

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Ho Ho Ho all I feel is the feeling I get waiting for the next niggly fault to arise, it's called stress

Cold / damp /dark miserable weather is coming so you won't need to wait long

Datatek is going really dark on us recently lol.....or is it just me still being in the 'honeymoon' period with mine - only 7 months in!

All I know is that I spent more time underneath mine than I did driving it.

Stay on top of maintenance and I mean preventative maintenance and regular inspection of suspension and associated items, and ABS (sensors in particular) etc is a good idea on these cars (don't cheat on spare part or oil quality) and don't offroad it and you may get lucky. I'd probably got rid of most of my cars gremlins when the autobox went loopy (started slipping in all gears) and I gave up.