Roger Parker on the K Series and HGF

In a posting on the MGOC BBS in January 2006, Roger discusses the issues of HGF on the K Series that affected the Freelander, MG F/TF and occasionally the ZR/ZS, and Rover 200/25 and 400/45, and 75 where fitted with the K series.

"HGF in the K series is a very complex issue and there are only some main common issues. The facts are related to the numbers of conversations I have had made by owners and personal experience of many K series engined cars during the whole life of the K series. My experience started with driving experience with one of the long term test Montegos fitted with development K series in 1988.

Firstly the design is unusual even today and of course it was originally an engine designed to be a 3 cylinder 1 litre through 1.1 to 1.4 litre 4 cylinder.

The other point of interest is that the use of nylon dowels to locate the head to block is chosen following repeating problems of corroding between steel dowels and alloy heads of other Austin Rover/Rover engines of the period. This led to many instances of damaged heads in extracting them needing new heads. It is also interesting to note that the O series family of engine also had a head gasket issue in the leakage of oil around the corner of heads near number 4 cylinder. Here though it was a combination of oil drilling location (feeding the head) and the material in the in-built oil seal in the head gasket.

The K series design creates a sandwich where the head is bolted to a ladder rail under the bottom of the block and the bolts are stretch bolts that provides the clamping load. However, the maximum clamping load is not achieved until after a new engine goes through a complete thermal cycle, i.e. up to normal operating temp and then back to cold.

Now no one has ever confirmed this but I suspect that this final 'maturing' process of the engine does on some engines see some uneven clamping loads created then over a period of use contributes to a weakening of the gaskets sealing abilities aided by additional thermally induced engine movement during many warm up cycles.

I have noted that 25 to 30,000 miles is often the point of a failure irrespective of age or type of use.

The pre 1999 built MGF is a country mile ahead of any other K series engined car in respect of failures, and witnessed by me recording over 900 instances of failures in MGFs between 1998 and 2002.

That comment on the thermal issues affecting the engine when you view the layout of the MGF cooling system and the over twice the volume of coolant than a fwd car. The longer travel of coolant pipes between engine and rad also contributes to the fact it takes much longer to reach normal operating temps for all the coolant and indeed there is always a greater degree of temp reduction in returning coolant on MGF than a FWD car.

Next is the design and location of the thermostat, on the inlet back into the engine, rather than the outlet from the head. This is controlled by a coolant bypass which sees coolant loop from the head outlet around to the side of the thermostat housing where the hot coolant is directed onto the thermostat bulb. As coolant warms quickly this soon causes the thermostat to start to open and a surge of cold coolant is introduced to the bottom of the engine block. The head and block now have different temps and so this sees some thermal movement.

As the cold coolant flows at a much higher volume than the flow from the bypass the thermostat then closes and then there is a rise in coolant temp entering the bottom of the engine. This cycle continues and the wide temp band continues for much longer on an MGF than any FWD application, but it is common on all cars to some degree.

The stress factors and other issues are I believe contributing potential failures, but whether this will occur depends on a number of other factors such as the stress factors from the first initial use of the engine. This is akin to saying that some people will get certain illnesses and others not because it is in their genes. Some engines are destined to suffer.

In the event of a failure then the strip down removes any clamping loads and sees all parts reset so without the maturing seen with new engines the stress build up doesn't now occur, hence repeat failures are much rarer.

Whilst much criticism is made of Rover and MG Rover in the way they handled (or didn't) cars suffering head gasket failure, they were sensitive to it and introduced a raft of changes to help reduce the problem.

These had a quite significant effect on cars so from around 1999 failures were much reduced. However, it was spring 2001 when the nylon dowels were replaced by steel dowels. This is one of the most significant improvements to all engines irrespective of model and is now a standard fit whenever a gasket is replaced. Therefore all MG saloons have the benefit of these.

The failure rate for TF, ZR and ZS are similar, but I have only noted TF failures for comparison to MGF as the cooling systems have the same basic formats. From the introduction of the TF to today I have recorded just 22 TF failures and all of these are pre-Summer 2003 built cars. A striking difference and had the previous high failure rates in older cars with K series not been present then this rate of failure would have been seen as simply par for the course and nothing special, but it isn't.

In practical terms the TF and Z range do not have a failure rate that should demand any extra action other than the correct routine maintenance, regular fluid checks and any coolant issues dealt with very promptly.

Where a failure occurs then the use of a genuine MG Rover gasket is preferable and the recent (I noted this early 2005)changes have not seen a change in part number, but there are additional sealing strip sections around known vulnerable areas where the gasket is known to fail.

Summer 2003 saw the TF gain the Pressure Relief Thermostat (PRT) where the thermostat is moved into the coolant line from the head rather than in the return line. This has a significant effect on smoothing temp variations.

A hint here for older engines not using a PRT is to drill a 3mm hole in the thermostat flange and then the stat refitted with the hole placed at 12 o'clock. This wouldn't allow a production engine to meet the emission and other requirements, but on an engine in a registered car doesn't have any such problems.

The controlled bleed helps to reduce thermal variation and thermal movement in the engine. It increases warm up time and has a slight impact on fuel consumption. However, this is not going to add up to the cost of HGF replacement. It can also be included during a scheduled coolant change or if desired at another time for relatively little extra cost.

Overall this long entry still only scratches the surface of the issues involved. This long running issue is something that I am quite familiar with, having spoken to around 1000 MGF owners whose cars have suffered HGF. Interestingly, and fortunately, by comparison more recent MGs don't reach 3.5% of that depressing number."

Roger again discusses further issues specific to the MG F/TF again in January 2006 and refers to the latest upgrades on the gasket and bearing ladder.

"Many things have changed since the peak of MGF failures, in the 1998 to 2001 period, which is essentially with pre 1999 cars. Spring 2001 saw the significant step in introduction of the steel dowels which was the biggest single retro suitable change, and why all gaskets now have replacement steel dowels in the package as standard. Most significant that is until now perhaps!

The TF arrival in 2002 saw yet another significant step in a different radiator and airflow changes that sees engine bay temps running at around 20% lower then an MGF. Interestingly of the small number of TFs suffering HGF I have yet to find one that is newer than 53 Reg.

The reason is the next really significant change with the PRT, Pressure Relief Thermostat, which saw the thermostat moved to the outlet coolant flow from the head rather then and inlet next to pump. Retro fitting a PRT to earlier TFs and MGF is possible but needs many items changed, so is not a simple one, nor cheap.

TF like MGF before it has over twice the coolant volume compared to a FWD application, due to the engine position, and this sees much more thermal cycling during engine operation, but especially during warm up.

Head shuffle (movement between head and block) is a common cause of damage to the silicone track of the head gasket leading to sealing failure. The steel dowels reduce this but there are other issues. A consequence of coolant loss, even minor in terms of overall volume, is often enough to create airlocks, another sensitive are for K series, and this then restricts coolant flow and leads to overheating, more thermally induced movement.

Overheating then often causes damage to the head, be that warping or more damaging softening of the head material specifically around the fire ring area where the gasket contacts the head face.

For a while now rumours have circulated from former MGR people to the effect that Powertrain have been aware of both the reasons for K series HGF and a cure for it. It may be coincidental, but I doubt it, that Land Rover have recently released a new style head gasket assembly, together with other parts to replace all previous gaskets used on all 1.8 litre K series Freelanders. As up till now the same gasket was used as on all other K4 engines the inference is clear.

The new gasket is a 5 piece coated multi metal shim type with an additional separate coated shim that is fitted between the gasket and head with a specially coated side facing the head face. There is no silicone tracks in sight and it is interesting to note a similarity with the Klinger gasket with a very similar construction that was adopted for the T series engine around 10 years ago, after over 10 years of oil leaks from O, M and T series head gaskets and a multitude of standard configuration gasket updates.

Additional Land Rover K series changes include, of all things, a new lower engine rail, the one into which the long through bolts (not head bolts as many call them) screw into to clamp the whole engine sandwich.

Visible changes are obvious and the clear purpose is to add strength witnessed by additional bracing webs, thicker webs and 20% increase in the weight of the rail.

Again word of mouth only says that the same through bolts and the same torque and tightening setting apply as before.

It is further said that the new rail and the new gasket assembly have to be used together for the full effect to be achieved.

Land Rover have a 'multi metal shim gasket bulletin' issued to dealer which I have not seen, but would obviously like too!

Additional rumour says that this development was connected to Euro IV development and may have seen production life when these engines appeared, which of course they have not, but who would bet against a Chinese K series featuring this?

Best part is that the new gasket assembly of the 5 layer gasket, additional coated shim and the mandatory steel dowels come in a single box priced at £23 plus vat retail. The new rail comes at £29 plus vat retail from your local Land Rover dealer. A leaflet in the gasket box confirms that the gasket is suitable for all 1.8 Freelanders and the existence of the Land Rover bulletin.

Part number for gasket assembly is LVB500190 and the number for the lower rail is LCN000140L. Note that the gasket on its own has and LVB prefixed number stamped into the top face, but don't ask for it.

As the gasket has no silicone tracks to be dislodged, the head shuffle, even though it is greatly reduced in the newer engines, will not see the leakage of coolant either to outside the engine or inside to the sump. The multiple metal shims will allow that movement without damage and whilst maintaining the seal.

The additional coated shim will be able to help spread spot clamping loads applied to the head face but also provide an additional fire ring seal to reduce risk of material softening in the head.

I am assuming that the new stiffer rail will help the clamping load and further reduce the ability of the engine to see shuffle between head and block.

All in all this is promising development and had it been introduced by anyone other than Land Rover (who have been stung with heavy HGF with Freelander) there would be a great deal of scepticism. However, being as it is Land Rover, you can bet that they would make no move that would expose them to more problems and only change things with a guaranteed results.

XPart, being next door to the Land Rover spares operation, know about these developments but currently maintain that the gasket they currently supply (uprated on the last 12 months anyway) if used in accordance with instructions, provides more than adequate service. I have to say I haven't had problems with many that I have fitted, but feel that belt and braces is better than just belt.

Uprated gaskets are all essentially the same, but I personally wouldn't use one on any of my jobs. The standard gasket, assuming this is the latest variant from XPart will, when everything else is correct, work perfectly well. I have some pretty powerful and highly stressed engine experience with standard gaskets and have only had one problem with a head that went soft and the gasket sank into the head material and so didn't seal for long. Payen do a 'Head Saver Shim' to help recover head that have suffered this or warped too much to be skimmed and reused under normal circumstances."

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