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Rover - K-series head gasket failure prevention?  
K-series head gasket failure prevention? - John F
Forgive me if this has been suggested before, but would it be worth retightening the cylinder head bolts routinely every 40,000 miles or so?
Many years ago I had a Passat GL5. When it got to 120,000 miles and wasn't worth very much I heard that head gaskets sometimes failed from then on. So with nothing much to lose I uncracked the head bolts in turn and retorqued them. It was still going strong at nearly 200,000 when I eventually sold it although it did barely 1000m per litre of oil by then.

I suppose head gaskets fail because the cylinder head is no longer squeezed firmly against the block. Repeated expansion and contraction presumably stretches the bolts very slightly, and if the distance between the threads and the heads of the bolts is great, the stretching will be more pronounced.
Might it be as important to do this at 100,000m on any engine as changing the cam belt?

Tags: technical issues maintenance and servicing cam belts cam belt oil

K-series head gasket failure prevention? - Altea Ego
Forgive me if this has been suggested before but would it be worth retightening the
cylinder head bolts routinely every 40 000 miles or so?

the block. Repeated expansion and contraction presumably stretches the bolts very slightly and if the
distance between the threads and the heads of the bolts is great the stretching will
be more pronounced.


No, you should NOT tighten the bolts on a K series. They are in fact already "stretched bolts" that go all the way through the block of the engine. They are torqued down to its elastic point when manufactured.
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< Ex RF, Ex TVM >
K-series head gasket failure prevention? - Number_Cruncher
As mentioned by Deed Poll above, you shouldn't re-tighten these bolts.

Many cylinder head bolts of cars of the last 20 years have been torqued to yield, or in some cases beyond yield, there's nothing to gain (and much to lose) by re-torquing.

There's lots of theories about why these head gaskets don't last too long. I don't know how much work has gone in to validating or proving any of these ideas.

On the K series cylinder head gaskets I've seen, which have failed, there's usually some local material loss in the head in the area around the firing ring. For this reason, I think it is best to skim the head when the head gasket fails.

Number_Cruncher
K-series head gasket failure prevention? - John F
'you shouldn't re-tighten these bolts.
> Many cylinder head bolts of cars of the last 20 years have been torqued to
yield or in some cases beyond yield.........'


What is 'yield'? Surely 'beyond yield' means they either break mid-shaft or strip the threads. [as I have just done on one of my 40yr old Webb mower Villiers aluminium block holes - it still works, though - even better minus the spoonfuls of carbon...!]

Presumably the average torque required to break them is measured experimentally and then the actual torque at manufacture is well below this figure, otherwise there would be a sizeable percentage of dysfunctional headbolts leaving the factory. So I need a better reason why they should not be retorqued [purely out of interest as I would not dream of owning such a poorly designed engine].
K-series head gasket failure prevention? - Altea Ego
What is 'yield'? Surely 'beyond yield' means they either break mid-shaft or strip the threads.
Presumably the average torque required to break them is measured experimentally and then the actual
torque at manufacture is well below this figure otherwise there would be a sizeable percentage
of dysfunctional headbolts leaving the factory.


No you completely missed the point about these bolts. The are manfactured with an elastic portion in the centre of the bolt that is designed to stretch and provide extra "active" tension.
(rather like an elastic band)

To get to this point they are torqued to a precise level. Once torqued to this level they can no longer be safely retorqued again as they have already been stretched once. If you try they suddenly become completely over elastic and have no grip at all.

I saw a programe on the tele once about the design and construction of the K series engine. To be fair the design and engineering of the basic block and head were revolutionary, providing at that time excelent power to weight ratios. Somewhere along the line after the basic design work it all went to rat poo. Probably in an effort to save cost or make it do what it was never meant to do
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< Ex RF, Ex TVM >
K-series head gasket failure prevention? - Number_Cruncher
>>What is 'yield'?

Where the bolt's behaviour changes from purely elastic (i.e. returns to original size and shape after the load is removed) to plastic, where there is some permanent deformation.... This is NOT the same as breaking the bolt - that would be at ultimate stress, rather than yield.

There are a couple of good reasons to torque to yield.

First, if in the factory you tighten the bolt with a machine which simultaneously measures the torque applied and the angle turned through, you can accurately set the bolt on the point of yielding (regardless of exactly how much torque you are actually applying). This allows you to make the best use of the bolt's elasticity, and removes a lot of the uncertainty and therefore design margin you must allow if you use only the crude method of tightening to a pre-set torque. Using a torque wrench - or any torque sensing device - to tighten bolts is an awfully imprecise way of doing it - which is why most cylinder head bolts are prescribed a snug torque plus a known angle as a method for tightening in service. Snug torque plus an angle is much more accurate.

Second, if you go a little beyond yield, the gradient of the stress / strain curve for the bolt becomes more shallow. This sounds bad, but is actually extremely helpful. As an analogy, imaginepacking some items onto a roofrack. You have a choice of fastening them down with a stiff chain, or a stretchy rope. If you use the chain, as soon as the load shifts and settles a bit, the chain will lose all its tension, because there was virtually no stretch in there to begin with. If you use the rope, as the load shifts, the rope does relax a bit, but it still retains some tension, because it stretched further to begin with. So, oddly enough, a bolt which *isn't* stiff is really helpful ina situation where you may get some relaxation, like a gasket settling.

In short yield does *not* equal break - unless your cylinder head bolts are made from a brittle material like glass or chalk!!

Number_Cruncher
K-series head gasket failure prevention? - John F
Many thanks to Number_Cruncher and Altea Ego for such interesting info and explanations; the concept of head bolts with both elasticity and plasticity is fascinating. Sounds great in theory.......shame it doesn't seem to work in practice, although perhaps it does in other types of engine.

Perhaps it might be possible to install heat-resistant pressure or bolt tension sensors which indicate how tightly the head is squeezed against the block, so when it looks as though too much plasticity has developed and things are getting a bit loose one could just replace the bolts.....idle thoughts on a cold rainy w/e...I suppose nothing can save an engine if it is prone to get too hot and warp from various design and manufacturing shortcomings as mentioned by 659FBE.
K-series head gasket failure prevention? - Number_Cruncher
>>shame it doesn't seem to work in practice

Oh, it does work in practice. I've done some work on bolt tightening of some rail vehicle parts where the load in the bolt was measured using strain gauges. The theory does work. Among the things I have learnt by doing the measurements is just how carp a method of tightening bolts a torque wrench is!

For another project, I'm currently writing a small software tool that partially automates the process of designing a bolted joint - it is based on the guidance given in VDI 2230. If, in the program, you specify torque to yield, via contemporaneous torque and angle measurement, you can typically drop a bolt size or two when compared with using a purely torque measurement tightening method. (Note, this is applicable at design time, it's not something that you can apply retrospectively to existing designs).

One of the more interesting bits of bolted joint design is how load is shared between the bolt and the joint. If when you assemble joint the two clamped parts are forced together and develop intimate contact, they form a parallel loadpath with the bolt. If you then apply a load pulling the joint apart, as long as the joint doesn't seperate, the bolt and the joint share this extra load. In a well designed joint, the bolt takes about 10% of the load, while the 90% is borne by the joint. Amazing, but true! Without this protective mechanism, bolt failure via fatigue would be much more common. Indeed, in a previous project I have corrected problems with poor bolt fatigue life by imposing assembly precautions that prevented poorly assembled joints being put into service.


For the K Series, the shortcomings as described by 659 are so great thet they overcome an otherwise reasonable bolt design idea.

Number_Cruncher


K-series head gasket failure prevention? - Pugugly {P}
That has to be the acme, nay the epitome of K Series issues replies and deserves to be framed....!
K-series head gasket failure prevention? - dk54
Best way to help make them last longer is to change coolant on time and change thermostat every year,also drill a small hole in stat to help prevent airlocks.

But whatever you do dont disturb the head bolts unless you are changing gasket/head!!!
K-series head gasket failure prevention? - 659FBE
As a diesel specialist, I'm not familiar with the finer points of the K-series but I understand that the thermostat location is fundamentally flawed.

For a thermostat to work properly, the heat sensitive wax capsule has to see water hot enough for the valve to open when required. My understanding is that on the K-series this doesn't happen and the engine can boil with the thermostat closed under some circumstances. Some die hards have produced a kit to relocate the thermostat to avoid this problem - maybe worth a look.

Purists will not approve of re-torqueing stretch head bolts but I've done this sucessfully a number of times when the signs of leakage are very slight - ie early on in the problem "cycle". It has worked on non marginal engines where the gasket firing ring relaxes slightly, reducing the preload on the bolts. I've never done this on a K-series and it probably wouldn't work on such a poorly designed engine.

I'm so glad they never tried making a diesel version.

659.
K-series head gasket failure prevention? - cheddar
>>on such a poorly designed engine>>

To put this into perspective the 1.1 and 1.4 8vs units are fine, early 1.4 16vs did not suffer HGF above the norm, it was the introduction of the 1.8 that brought the HGF reputation, the 1.6 is less prevelent (though my BiL had a 1.6 400 that suffered HGF) and the 1.4 less so again.

The issue seems to be caused by a combination of a couple of points any one of which could easily be addressed.

On a related matter HJ suggests in yesterday's DT that someone could produce a kit to fit a Ford, or similar, engine to 1.8 Freelanders that seem to suffer the HGF probs above the K Series norm, perhaps someone already does this?
K-series head gasket failure prevention? - jc2
Not fitting a Ford engine as such but Ford developed a new head gasket for use on this engine when fitted in the Land Rover.
K-series head gasket failure prevention? - cheddar
Does that mean that K series Freelanders from a certain age are HGF free?

If so is this retro fitable to early K Series?
K-series head gasket failure prevention? - jc2
I don't know-all I do know is that Ford spent a lot of time & money developing a new gasket.
K-series head gasket failure prevention? - Cliff Pope
I have always understood that the main cause of gasket failure on any engine is either initial incorrect torquing, or else overheating. Some engines are more robust in this respect than others, but on a known weak engine it would make sense to take excessive precautions.
Annual coolant flush and renewal, including thermostat testing or replacement, use of proper and adequate anti-corrosion additive, and having a proper temperature gauge and knowing how to interpret it.
K-series head gasket failure prevention? - 659FBE
Cliff, there are two other causes of gasket failure which you left off your list - bad design and poor manufacture.

The K-series has both. The liner preload, gasket compression and liner bottom location are not properly designed or toleranced, leading to firing ring fretting on the underside of the head. Their chosen gasket supplier had no experience of sealing this type of engine - they should have gone to PSA's supplier instead. The cooling system design is bad. The powertrain factory were also incapable of exercising proper quality control on material specs or dimensional tolerancing.

The rest is - as they say - is history. Engineering is a great leveller; cock-ups will always come back to get you.

659.
K-series head gasket failure prevention? - Aprilia
Failure prevention?

Well, replace the radiator every 4-5 years. They are cheap and nasty on Rovers and don't last long - they are very cheap however (£70 or so from my factor).

Go to Land Rover dealer and buy the new multi-layer steel gasket. The liner heights must be correct to use these however - if that's not the case then you have to use the old type gasket.

From what I hear and see, you are borrowed time once one of these engines is over 5 years old...
K-series head gasket failure prevention? - GregSwain
HGF is part and parcel of K-series ownership, just as EGR valve failure is on a Renault DCi. If you want to avoid these alarmingly common faults, don't buy a car with the engine in question. Seems the only realistic way of avoiding K-series HGF: don't buy a K-series! :-)
K-series head gasket failure prevention? - Robin the Technician
Taken from my earlier post re 'K' series head gasket failure. As to your comment re the manufacturer, Federal Mogul are the largest manufacturer in the world for gaskets.

Quote:
For those who need to know why this is common on 'K' series, here is the definitive answer. If you look at the head gasket for this engine, you need to look closely at the pressed in rings that circle the bores. You will see they are pushed through from the underside and then crimped over. This means that this crimping press's directly onto the head face. When the gasket fails, these 'fire rings' as the are called become loose and 'chatter' against the head causing the familiar groove which necessitates the head being skimmed.
How do I know this? I worked for rover for 15 years in Problem analysis dept and later as a Product Specialist for Unipart. I met with the guys at Federal Mogul (Payen to you) who at the time supplied these gaskets OE to Rover. There was considerable discussions about turning these fire rings over to be crimped on the side that sits on the cylinder liners (the theory being that the liner was harder than the fire ring and no damage would occur to the liner or head) but the cost of changing all the tooling was prohibitive.


--
These are the views of Robin the Technician with 35 years in the trade. I fix, therefore I am...
K-series head gasket failure prevention? - dk54
>>but the cost of changing all the tooling was prohibitive.

To put it another way,were making plenty of money so why change it
K-series head gasket failure prevention? - 659FBE
Or to put it another way, they didn't know how to design a wet liner engine in the first place.

Copying the PSA engines seemed like a good idea at the time, but as we all know - in engineering, the devil is in the detail.

659.
K-series head gasket failure prevention? - Xileno {P}
"On a related matter HJ suggests in yesterday's DT that someone could produce a kit to fit a Ford, or similar, engine to 1.8 Freelanders that seem to suffer the HGF probs above the K Series norm, perhaps someone already does this?"

I have no doubt that it could be done with a lot of work modifying supports, brackets, ECU settings etc but it would never be finacially sensible to do compared to getting another K Series inserted with no hassle. Then sell the wretched thing before the HG goes again...

In time the 1.8 engine will just disappear off the face of the Earth. In my opinion that will be a good thing.
K-series head gasket failure prevention? - jc2
Now you know who was responsible,send all your bills to Robin!
K-series head gasket failure prevention? - cheddar
Seems that a later Ford/LR modded Freelander K-Series could be a good upgrade for an Elise etc unless the block and head castings are different so ancilliaries and mountings are different.
K-series head gasket failure prevention? - Chris S
The best way to avoid headgasket failure on a Rover is to do what I did - sell it and by a Nissan!
K-series head gasket failure prevention? - cheddar
sell it and by a Nissan!


No, that is about the 43rd best way ;-)
K-series head gasket failure prevention? - Robin the Technician
Thanks JC2......... Blame a poor, hard up ageing ex Technician.....hahaha!!!!

I was just there for the meetings with Federal Mogul - I was not part of the decision making. You also have to consider that if FM had changed the design, this forum would be a lot lighter and full of people ACTUALLY extolling the virtues of owning a car with such a 'marvellous engine'.
Pigs fully fuelled and ready to fly!!!

Cheers




--
These are the views of Robin the Technician with 35 years in the trade. I fix, therefore I am...
K-series head gasket failure prevention? - GregSwain
You also have to consider that if FM had changed the
design this forum would be a lot lighter....


Call me a cynic, but might they have opted for the cheaper "do nothing" approach, because it'd be Rover's reputation going down the toilet rather than their own?
K-series head gasket failure prevention? - 659FBE
It's not really fair to blame Federal Mogul for Rover's shortcomings. Don't forget, Bentley used to make engines without head gaskets - they fitted.

Rover did not have the necessary expertise to design an engine - let alone a wet liner unit with a high specific output. They chose a gasket supplier with whom they had worked for many years but who had no expertise in this type of application. If they had, they would have warned Rover at the development stage that their design was unlikely to work. Component suplliers have a lot of know how - I've worked for some of them.

This thread really ought to go to bed now.

659.
K-series head gasket failure prevention? - normd2
A colleague who races a Caterham look alike with a K-series told me, when you start from cold wait for the temp guage to come up then wait five minutes more before attempting anything other than sedate driving. Cane it when it's cold and you're asking for trouble when the thermostat opens.
K-series head gasket failure prevention? - DP
Cane it when it's cold and you're
asking for trouble when the thermostat opens.


I think this is the biggest problem with the Freelander. It's quite hard not to work a 1.8 litre engine hard when it's lugging 1500-odd kg of 4x4 around.

Land Rover sell the Pressure Relief Thermostat kit which has been fitted as standard to all K-engined Freelanders since 2002 along with a modified head gasket. Apparently, this has drastically reduced hgf rates to a tiny fraction of what they were. We're going to fit a PRT kit to my dad's as a precaution (the kit is about £50). This 'stat is not only relocated from its current idiotic location, but it works on pressure difference as well as temperature. It apparently starts opening earlier, and quicker in response to high engine speeds as well as coolant temperature.

Although designed to be a "plug and play" installation for a Freelander, there are various websites telling you how to adapt this kit for an MG-F or Elise.

HGF apart, this really is a lovely little engine.

Cheers
DP
--
04 Grand Scenic 1.9 dCi Dynamique
00 Mondeo 1.8TD LX
K-series head gasket failure prevention? - track
The use of a copper head gasket works very well on wet lined engines and should prevent HGF, but then its a false economy as the gasket needs to be at least removed and annealed every 3 years, preferably replaced. But at least for them 3 years you get a bit of peace from the HG worries.
How have lotus dealt with the issue as they are using K series units and dont seem to report such high failure rates?
I also read once in a car mechanics magazine that one of the chief designers at rover did indeed find the cure to the dreaded HG failure's but it was too late in the day to implement and rover wouldnt fund the replacements or make it public there was a cure for fear of a recall demand.
K-series head gasket failure prevention? - Altea Ego
How have lotus dealt with the issue as they are using K series units


They didnt so they now use different engines
dont seem to report such high failure rates?


afraid they did.

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< Ex RF, Ex TVM >
K-series head gasket failure prevention? - dk54
>>afraid they did.

IIRC failure rate of Lotus was higher than in Rover cars,reason being the coolant return pipe to stat from rad is a lot longer than in the Rover car so it got colder,in instances where the stat suddenly opened colder water rushed into block causing thermal shock,much the same on the MGF which was the reason for the stat mod
K-series head gasket failure prevention? - none
Many years ago I used to work on the Pre VW Skoda cars. The engines were wet linered but had a cast iron head and aluminium block.
I can't recall ever having to replace a head gasket.
K-series head gasket failure prevention? - Xileno {P}
No, because the Czechs were (and probably still are) good engineers.
K-series head gasket failure prevention? - 659FBE
What very little true Skoda design there is on my car as opposed to rehashed obsolescent VAG (complete with cock-ups), would confirm this.

659.

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