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Thread: Most Common Causes of "doing" a Head of Range Rover Classic

  1. #11
    Join Date
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    Ahh, Wiebull analysis , really not much good for the mythology of "Head gasket "Failure.
    When you use an MTBF or failure rate to describe the equipment's failure behavior, you are assuming that failures occur at a constant rate regardless of the age of the equipment (i.e. an exponential distribution). Other statistical distributions are more appropriate for situations where the failure behavior varies with time, as in the case of infant morality or wearout.
    In fact if we did a simple FMEA that actually clearly delineated actual failures of the gasket , and not consequential failures then we might be surprised with the results.
    Simply if the head gasket "blows" so to speak, was it a fault of the head gasket per se , or some other factor such as a overheating excursion (a little chicken or the egg thinking)
    Perhaps we could start with a list of failure modes for head gasket itself ?
    A Failure mode best described as Component/symptom/cause
    Component = Head gasket
    Symptom i= the observable condition found
    Cause = What lead to the condition/symptom ("FAILED" is not a symptom)
    Head Gasket-Incorrectly manufactured-lack of QA/QC
    Head gasket-malformed-incorrect storage/distribution
    Head Gasket -Blown-incorrect material used in Construction.
    And a few more failure modes that consider just the the head gasket.
    Now, Head gasket-leaks compression- incorrect fitment(tensioning)
    Head gasket -leaks water into oil - incorrect fitment
    Head gasket leaks oil into coolant system -incorrect fitment
    Head gasket-blown- exceeded design fatique rating
    Head gasket - blown - Excessive Dynamic compression ratio
    Head gasket - corroded - lack of suitable Coolant management strategy
    Head gasket - Blown- mating faces of head and or block not up to spec.
    Head gasket - Blown/leaks - basic machining angles wrong.
    And theres a lot more failure modes !!!
    What are the functions and associated desired standards of performance of the asset in its present operating context (functions)?
    Thats the hard part ! what its supposed to do for what period.
    Although Nomad9 claims to like Predictive maintenace , he is actually suggesting that the preferred strategy is a Preventive one, in that regardless off condition , Change out the Head gasket ! Using a Predictive strategy, would mean doing Water Analysis, Oil analysis, compression Analysis and allowing the "condition" found from these analysis's's's's to dictate changeout (Dont ferget Detective and Corrective strategies as well)
    Its this 120K thats hard to get your head around . Lets say at an average road speed of just 20KPH that would be around 6000Hrs of operating ,
    Spread that 6000 hrs over say 4 years and thats 1500 Hrs operating a year, or as much as 5.6 hrs per day every day . (delivery truck type numbers!)
    Now lets try the standard of 20,000 K per year = 6 years for the magic 120K
    Lets say average joe is around 2Hrs (max per day every day of the year)so say 700 hrs of operating per year , over 6 years ,say 4000hrs per year .
    Better still would be to use heat cycles . A guess would be around , on average 2 a day or 700 a year (simply starts and stops from cold to somewhere near operating temp)Again around the 4000 mark ,intereting !!
    yeah,whatever !!!

  2. #12
    Join Date
    May 2007
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    Hi There,
    I'm impressed, I agree with everything you've said how could I disagree you are right. When I was looking at buying a Land Rover, in this case typically a 300 Tdi which is what I based the 120k on I was looking at the engine as a component, rather than each individual part of the engine.
    I started on the vehicle, when the vehicle didn't perform its function which was to move under its own power in a forward or backward direction. Then analysing what major component failed, other major units had suspensions. The engine came out as one major component then split this down into major components and did the same exercise, the head as a major component came out as a failed item as you mention for various reasons, doing a bit of an RCFA you can come up with a whole raft of reasons the head failed as you point out, one being the gasket, why did the gasket fail, again could be a multitude of reasons, the thing is the head failed to perform its designed function.
    When you get enough samples from all over the place, workshops and phoning people up enquiring about a vehicle, getting some history, assuming that people tell the truth you can put a few samples on the graph. On the results I got when 62.5 % of the population will fail was around the 120k mark. I didn't want to get carried away with to much detail I just wanted to get a number, something to work with, so far to date for me this number seems to still play out.
    Very interesting email, you never know we might meet one day.

  3. #13
    Join Date
    Aug 2011
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    Melb
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    "Hi Vanderz,
    I've found that if you replace the gaskets on a 120K basis this eliminates the majority of problems. This head gasket/s change also includes critical hoses. You will always find the money to do a $2000 engine repair but somehow you can never find the $120 to replace all the hoses when they appear to be fine.


    When you refer to "ALL" the hoses i assume you mean top and bottom radiator hoses? anything else?

  4. #14
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    May 2008
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    Quote Originally Posted by bee utey View Post
    The main reason I have seen for early failure of alloy V8 head gaskets has been on engines with a blocked bypass/heater circuit. The circuit through the heater on a RRC must be full flow to maintain even head temps with the thermostat closed. With the bypass blocked I have seen a gasket self destruct in 30K or less. Rapidly changing head temps due to the thermostat cycling will 'walk" a fire ring out the side to the water jacket.
    is there a way to not use the heater but not have this issue. I've been through 3 heater cores in the last 9 months and I'm sick of pulling the dash apart to get the bloody thing out.

  5. #15
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    Hi 400HPongas,
    Apologies, I checked what I used, it was late and I'd had a beer or two. I also used Crow/AMSAA, the diversity of people who own the LR brand is amazing. Have a nice break, if you want to really improve your reliability have I got an oil for you........ FMEA, lubrication is one of the most if not most important systems on the vehicle.

  6. #16
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    Quote Originally Posted by brend0n View Post
    is there a way to not use the heater but not have this issue. I've been through 3 heater cores in the last 9 months and I'm sick of pulling the dash apart to get the bloody thing out.
    Dead easy, just purchase a suitable shaped heater hose to loop the inlet and outlet together. Some of the early RRC's had 180 degree copper bends in the plumbing for the heater which would be ideal for connecting 2 parallel hoses together.

  7. #17
    Join Date
    May 2007
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    Byford, WA
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    Hi Vanderz,
    Do you know what I've never been caught by the top or bottom hose, I've been caught by the little by pass hose behind the water pump which is in a plick of a place to get to and a corroded pipe behind the plenum between the inlet manifold and the valley gasket, the leak here actually corroded on one of the bends of the the valley gasket, again another plick of a place to get to. Typically I replace the heater hoses and the two small bypass type hoses on a semi regular basis around 120 k or 5 to 6x years which ever comes first. Always keep a spare top and bottom hose in the back, relatively easy to fit if they do show any signs of deterioration.

  8. #18
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    cool i might look into replacing those as a precaution.

  9. #19
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    Quote Originally Posted by bee utey View Post
    Dead easy, just purchase a suitable shaped heater hose to loop the inlet and outlet together. Some of the early RRC's had 180 degree copper bends in the plumbing for the heater which would be ideal for connecting 2 parallel hoses together.
    Sweet that what I have done mine has the 180 bends,
    just saw alarms bells when mentioning heater core and bypassing lol...

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