Disco 2 advice please

sierrafery said:

3 x bad advice IMO ...eventually explain why would you do such things but with technical arguments if you can not that somebody said it's OK

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Have to agree with this. the dowels are not to hold the head in place they are to locate the gasket properly while the head is being replaced. So replace plastic with plastic and steel with steel.
You reuse the headbolts at your own risk. For the cost, no, don't do it.
And why fit a thicker gasket? you can lightly skim the head and if it is only a tiny bit out it'll pull stright under the tension of the bolts.
The above from the great James Martin, (except that he does have a tendency to reuse bolts but then he is more of an engineer than a lot of us and knows exactly when you can and when you can't.

Don't change the engine just the oily bits.

Stanleysteamer said:

The above from the great James Martin

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Is he still on here? Aint seen him for ages and I was lurking before I started piping up again

1988smithy said:

Is he still on here? Aint seen him for ages and I was lurking before I started piping up again

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Nope sadly he went off to play with his old cottage and smallholding a long time ago now.

glark1 said:

This is where I get so much different advice - the chap that has looked after my Defender 300tdi and now the TD5 disco reckons the TD5s are a bag of cack and I should get a Disco 3/4 but I get told these are crap too.

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Your so called 'Chap' is talking ?!?!?

Landrover Engines tdi's and Td5's are possible the best engines LR ever done??
High mileage '174k'???? for a Td5??? Thats a 'running in the engine' figure !!
And the only bad point about the engine?? Is the body around the engine??

However, Landrover knew that in 1948

Kev

glark1 said:

This is where I get so much different advice - the chap that has looked after my Defender 300tdi and now the TD5 disco reckons the TD5s are a bag of cack and I should get a Disco 3/4 but I get told these are crap too.

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He's talking rubbish - a TD5 that's been looked after will go forever.

Besides that replacing an engine is way more effort than replacing the oil cooler or even just the gasket, and you'd have no guarantee that a random replacement engine from eBay didn't have its own issues.

sierrafery said:

3 x bad advice IMO ...eventually explain why would you do such things but with technical arguments if you can not that somebody said it's OK

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What! bad advice to change those plastic dowels for steel ones because the plastic ones allow the head to move, which is most definitely the likely cause of a head gasket failure in the first place. bad advice to simply use the thicker head gasket, which avoids any tolerance issues and ensures a better seal. reusing the head bolts is a choice, after considering the elastic fatigue stresses they are subject to under compression and ignition, the variable stress range, which causes fatigue, is all in the positive and small enough to have little effect, the length of the bolts also helps, so I did reuse and all has been well for years now. I later spoke with a garage specialising in Land Rovers and they do the same and have for years.

Stanleysteamer said:

Have to agree with this. the dowels are not to hold the head in place they are to locate the gasket properly while the head is being replaced. So replace plastic with plastic and steel with steel.
You reuse the headbolts at your own risk. For the cost, no, don't do it.
And why fit a thicker gasket? you can lightly skim the head and if it is only a tiny bit out it'll pull stright under the tension of the bolts.
The above from the great James Martin, (except that he does have a tendency to reuse bolts but then he is more of an engineer than a lot of us and knows exactly when you can and when you can't.

Don't change the engine just the oily bits.

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Dowels dont hold the head in place, the bolts do that, but dowels are used to accurately locate the head on the block not just the gasket.
The plastic dowels are not robust enough to ensure location in the longer term and they can and do deform allowing the head to move slightly causing bridging between cylinders and water jacket.

Bantam1 said:

What! bad advice to change those plastic dowels for steel ones because the plastic ones allow the head to move, which is most definitely the likely cause of a head gasket failure in the first place. bad advice to simply use the thicker head gasket, which avoids any tolerance issues and ensures a better seal. reusing the head bolts is a choice, after considering the elastic fatigue stresses they are subject to under compression and ignition, the variable stress range, which causes fatigue, is all in the positive and small enough to have little effect, the length of the bolts also helps, so I did reuse and all has been well for years now. I later spoke with a garage specialising in Land Rovers and they do the same and have for years.

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It was already well explained by @Stanleysteamer. Better believe that rather than "specialists" who are making a living from such jobs and want to be as easy as possible for the money. If you want more evidence that it was bad advice and that you are wrong let me know and i'll deliver official docs.

Bantam1 said:

Dowels dont hold the head in place, the bolts do that, but dowels are used to accurately locate the head on the block not just the gasket.
The plastic dowels are not robust enough to ensure location in the longer term and they can and do deform allowing the head to move slightly causing bridging between cylinders and water jacket.

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Land Rover themselves issued a specific notice to the effect, "Plastic replace with plastic, steel replace with steel" it has been posted on a thread on here somewhere already.

Bantam1 said:

Dowels dont hold the head in place, the bolts do that, but dowels are used to accurately locate the head on the block not just the gasket.
The plastic dowels are not robust enough to ensure location in the longer term and they can and do deform allowing the head to move slightly causing bridging between cylinders and water jacket.

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If you reread my post you will see I said, exactly, "the dowels are not to hold the head in place"
I also said "replace plastic with plastic" not "reuse plastic dowels".

Stanleysteamer said:

Land Rover themselves issued a specific notice to the effect, "Plastic replace with plastic, steel replace with steel" it has been posted on a thread on here somewhere already.

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I guess if Land Rover said they had cocked up with the plastic dowels then they would have had a huge number of claims to deal with. Did they later go steel dowel anyway? My head gasket went at 70k and if you can imagine the dowels had stepped sideways at the head / block interface. Even that small movement was enough to cause the cylinder/water jacket to be breached and I had pressure in the cooling system. Since I've replaced the head gasket and used steel dowels it has run well but I wont know for another 50k if that upgrade lasts as long as the plastic dowels did. I believe all dowels should be steel and Rover made a huge cock up using plastic. All the motorbike engines I've built over the years are steel dowel and vital in maintaining accurate alignment of casings and heads. I guess if the collective judgement of the forum is only to advise what Land Rover officially say then go with that.

sierrafery said:

It was already well explained by @Stanleysteamer. Better believe that rather than "specialists" who are making a living from such jobs and want to be as easy as possible for the money. If you want more evidence that it was bad advice and that you are wrong let me know and i'll deliver official docs.

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Good advice on here would appear to what Land Rover say. Go for it.

Bantam1 said:

I guess if Land Rover said they had cocked up with the plastic dowels then they would have had a huge number of claims to deal with. Did they later go steel dowel anyway? My head gasket went at 70k and if you can imagine the dowels had stepped sideways at the head / block interface. Even that small movement was enough to cause the cylinder/water jacket to be breached and I had pressure in the cooling system. Since I've replaced the head gasket and used steel dowels it has run well but I wont know for another 50k if that upgrade lasts as long as the plastic dowels did. I believe all dowels should be steel and Rover made a huge cock up using plastic. All the motorbike engines I've built over the years are steel dowel and vital in maintaining accurate alignment of casings and heads. I guess if the collective judgement of the forum is only to advise what Land Rover officially say then go with that.

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I personally think the idea of plastic was a cr@p one anyway, in the first place. And as you say a lot of ass covering has gone on.
I cannot remember the reasoning behind not using steel where plastic had previously been used, on the same engine head combo.
And maybe just a minor point, but thicker head gaskets result in marginally lower compression ratios. Prolly not noticeable TBH.

Petrol engine, OK, But Dolomite Sprint engines whose heads warped for a pastime, you could get a range of thicknesses to compensate for the amount of head grinding that had to go on to get 'em flat!
Guess how I know!

Bantam1 said:

Good advice on here would appear to what Land Rover say. Go for it.

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I'll attach you the relevant docs about the dowels an hg bolts from LR later tonight which are the result of many years of research then you can decide(then i'll be on the laptop).... beside that google out "fitting thicker head gasket" for some different point of views

Stanleysteamer said:

I personally think the idea of plastic was a cr@p one anyway, in the first place. And as you say a lot of ass covering has gone on.
I cannot remember the reasoning behind not using steel where plastic had previously been used, on the same engine head combo.
And maybe just a minor point, but thicker head gaskets result in marginally lower compression ratios. Prolly not noticeable TBH.

Petrol engine, OK, But Dolomite Sprint engines whose heads warped for a pastime, you could get a range of thicknesses to compensate for the amount of head grinding that had to go on to get 'em flat!
Guess how I know!

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I think the reasoning over not using the steel dowel was something to do with the damage it may/would cause to the 10p head. There was a difference in the later all steel dowel motors to apparently accomodate this, well there would have to be wouldn't there?
Yes the compression is theoretically less but there are only 3 gaskets to choose from anyway and its no Ferrari.
Always wanted a Dolomite Sprint, back in the day, but never had one. Sounds like I was lucky.

Bantam1 said:

I think the reasoning over not using the steel dowel was something to do with the damage it may/would cause to the 10p head. There was a difference in the later all steel dowel motors to apparently accomodate this, well there would have to be wouldn't there?
Yes the compression is theoretically less but there are only 3 gaskets to choose from anyway and its no Ferrari.
Always wanted a Dolomite Sprint, back in the day, but never had one. Sounds like I was lucky.

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The Dolly Sprint was a fab motor when it was working, although it drank the juice.
Only motor that ever beat me, and that was because manuals at the time didn't tell you to load up the timing chain tensioner with petroleum jelly before reassembly. So I could never get mine to run right, timing advanced, it overheated etc etc.
Sold it to a bloke who sorted it and built a kit car round it. He sold it on.
New owner later joined my kit car club and was a member for years before we both twigged his donor had been my vehicle.
Bizarrely there is a bloke 20 miles away from our place here in France who used to run an Indy LR garage, sadly now only does parts, and his garage is stuffed with Dolly Sprints. He spends all his time working on them. He collects rare ones. He also told me that mine, which had an excellent body, Ziebarted from new, was of a very rare colour, Mimosa yellow or summat, and would have been worth even more.

The only thing wrong with it was that the local Triumph dealer couldn't deal with it, so I had to take it back off them after they fitted a new short engine and messed it up. I'd have it now if it hadn't been for that.

I still have an overdrive box for it, that I never got around to fitting.

sierrafery said:

I'll attach you the relevant docs about the dowels an hg bolts from LR later tonight which are the result of many years of research then you can decide(then i'll be on the laptop).... beside that google out "fitting thicker head gasket" for some different point of views

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I think I found those documents on here many years ago but also a lot of discussion and debate that helped me in making my mind up as to what I should do. The gasket thickness is a choice of 1 hole, 2 hole or 3 hole, all of which are standard LR to manage piston protrusion or valve I suppose and don't, or shouldn't, compromise the seal.
I'd rather not get technical info off Google though.
It may be worth getting the docs for the original post but I suspect they wont be doing any of the work themselves.

Bantam1 said:

I think I found those documents on here many years ago but also a lot of discussion and debate that helped me in making my mind up as to what I should do. The gasket thickness is a choice of 1 hole, 2 hole or 3 hole, all of which are standard LR to manage piston protrusion or valve I suppose and don't, or shouldn't, compromise the seal.
I'd rather not get technical info off Google though.
It may be worth getting the docs for the original post but I suspect they wont be doing any of the work themselves.

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at least 10 years of serious research which was all over the place not only on google m8... i have a friend with a LR scrapyard, 70% of the vehicles are Td5s, i've seen many of them, you might be amazed but 90% which had HG faiure or head cracks were fitted with steel dowels hence my "aggressive" reply, what i saw with my own eyes can't be beaten by any theory but i have the feeling that those who built the engine knew better, and as Stanley said those dowels have effect only untill the head is torqued up after that they can melt like ice without probs : see the "caution:


saying that something is good just thar some owners were lucky after botching things is not an evidence, reusing head bolts on a Td5 or on any vehicle which was fitted with strech bolts is a silly thing IMO, also from the builders :



thicker than necessary head gasket means lower compression and a real downgrade, that's a fact...believe it or not.

sierrafery said:

at least 10 years of serious research which was all over the place not only on google m8... i have a friend with a LR scrapyard, 70% of the vehicles are Td5s, i've seen many of them, you might be amazed but 90% which had HG faiure or head cracks were fitted with steel dowels hence my "aggressive" reply, what i saw with my own eyes can't be beaten by any theory but i have the feeling that those who built the engine knew better, and as Stanley said those dowels have effect only untill the head is torqued up after that they can melt like ice without probs : see the "caution:
View attachment 292067

saying that something is good just thar some owners were lucky after botching things is not an evidence, reusing head bolts on a Td5 or on any vehicle which was fitted with strech bolts is a silly thing IMO, also from the builders :

View attachment 292068

thicker than necessary head gasket means lower compression and a real downgrade, that's a fact...believe it or not.

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All good information and of course LR endorsed. LR are so good at R&D that the next generation V6 apparently breaks cranks, I even know someone this happened to so it is a thing it would seem. Lets not continue this debate, I dont find it to be at all useful. Good advice is to follow LR recommendations so go for it.

Bantam1 said:

All good information and of course LR endorsed. LR are so good at R&D that the next generation V6 apparently breaks cranks, I even know someone this happened to so it is a thing it would seem. Lets not continue this debate, I dont find it to be at all useful. Good advice is to follow LR recommendations so go for it.

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LR are, Ford are not