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300tdi - Why the different head gasket requirements?

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OK so I understand 1, 2, 3 & no hole gaskets relate to accommodating piston protrusion from the block but can anyone enlighten me as to WHY Land Rover felt it necessary to make engines of differing dimensions?  When I look back to my 1970’s basic apprentice training hand filing chunks of steel into true cubes I find it hard to believe that 90s technology couldn’t precisely engineer a standard block or piston.  Am I missing something here?  :wacko:

 

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I think it is more to accommodate when people skim the block.

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That could make sense if the “standard” gasket was 1 hole - then you’d have the opportunity to skim the block 3 times (not sure why you would though) however; my block definitely hasn’t ever been skimmed yet it has a 2 hole gasket . . . .

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Mine has a 3 hole and has never been skimmed. My impression is it's to allow for bad tolerance control in the factory.

Mike

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I have always wondered that, I’ve had maybe twenty 300tdis over the years, only one or two of them have not been 3 hole, and most of them I have known since new and have never had the head removed.

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my 200tdi had a 2 hole gasket when new & after the recent full rebuild inc head skim has needed a 3 hole gasket to accommodate the piston protrusion above the block face, must be down to tolerances when piston/conrods are made & matched up into sets. doubt any production machine could produce hundreds of matching length rods/pistons.

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From the workshop manual, you measure front and back of each piston (8 readings) and take the highest protrusion. Each gasket only covers a 0.1mm range. They may have just fitted 3 hole gaskets in the factory due to laziness or to be on the safe side.

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As said in a couple of posts above, I think it will be to cope with the tollerances when matching a set of pistons/conrods to a given block. It the block is on the lower side of the tollerance permitted and the piston/conrod set on the upper, then a thicker gasket will be required than if it is the other way round.

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20 hours ago, dailysleaze said:

From the workshop manual, you measure front and back of each piston (8 readings) and take the highest protrusion. Each gasket only covers a 0.1mm range. They may have just fitted 3 hole gaskets in the factory due to laziness or to be on the safe side.

That is my feeling.  3 hole is safe and Land Rover is lazy.  0.1 mm is a gigantic difference in tolerance for these parts.  Pistons and conrods should be made 100 times more accurately than that. 

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I guess I was just surprised at the manufacturing tolerances.  The difference between a 1 & zero hole appears to be .39mm which in old money is about 15thou - seems pretty relaxed & I wonder what BMW, Merc, Toyota etc work to and whether the same applies to modern J/LR engines

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6 hours ago, Red90 said:

That is my feeling.  3 hole is safe and Land Rover is lazy.  0.1 mm is a gigantic difference in tolerance for these parts.  Pistons and conrods should be made 100 times more accurately than that. 

My thoughts exactly. I can’t imagine Yamaha for example having 0.1mm variation.

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in 2017 deutz engines still have the choice of 1-3 hole multi layer head gaskets its not just lr doing it 

 

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Most push rod diesels are built just like the TDI and they normally come in one standard gasket size.  They usually only offer thicker gasket for when the block is decked.  You seriously need to try to do a bad job to need different gasket for a new engine.

Edited by Red90

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