Land Rover Freelander Head Gasket and Engine Problems

 

The Land Rover Freelander have had serious problems of head gasket malfunction which will lead to engine failure.  First signs of a problem include coolant leak, overheating, and engine performance problems.  This will usually lead to the engine failure which characterizes the 2002- 2005, model years of the Land Rover Freelander manufactured with the KV6 2.5 liter aluminum V6 engine.  Owners may be entitled to compensation.  Here is a more technical overview.  

Design and Components of the Vehicle

 

This engine is referred to as an aluminum V6 engine because it is manufactured using an aluminum cylinder block along with aluminum cylinder heads. Many internal components are however made of steel and iron. Most automotive manufacturers today offer aluminum V6 engines that would fall under this description. The KV6 engine shares several technical features with other manufacturer’s aluminum V6 engines of the 2002-2003 period such as double overhead camshafts, four valves per cylinder design cylinder heads, and variable intake manifold tuning.

 

One distinct design feature of the KV6 engine that makes it different from common aluminum V6 engines is the use of slip fit steel cylinder sleeves (or liners) in it's construction. All of the aluminum V6 engines that I have been exposed to (from Chrysler, Ford, GM, Honda, and others) use a press fit cast iron cylinder sleeve. Typically, engines using the cast iron cylinder sleeve design have demonstrated virtually no issues related to the sleeves or their integrity as assembled in the aluminum cylinder block. This is not the case with the KV6 engine design. I discovered an alarming number of reports describing failures (head gaskets and engine seizures) related to the sleeves of the KV6 engine.

 

Typically when aluminum cylinder block-iron sleeve engines are manufactured, the cylinder bores of the aluminum block are slightly smaller than the outside diameter of the cast iron sleeves before assembly at room temperature. This difference in sizes is referred to as interference and won’t allow assembly while the block and sleeves are both at room temperature. The block is heated to over 600 degrees F to allow it to fully expand before the cool or room temperature sleeves are pressed (forced) into place within the block and then allowed to cool at a controlled rate as an assembly. The amount of force used to press the sleeves into the block varies with designs and can be from a few hundred pounds to a few thousand pounds. This process assures a permanent, unchanging fitment of the sleeves to the cylinder block.

 

With the Freelander engine the sleeves are simply slipped into place as the engine is assembled. The sleeves of the Freelander engine have a shoulder machined into them about midway down the outside of the sleeves which rests on a machined land within the cylinder bores of the engine block as the engine is assembled. The sleeves essentially have two outside diameters with the lower end being smaller than the upper. It would be critical that these machined surfaces be of high quality and precision as once assembled, the contact area of the two surfaces would have to provide a seal between the coolant jacket of the cylinder block and the engine crankcase where the engine oil is collected and stored in the engine oil pan. The Freelander engine design relies on the clamping force of the cylinder head and gasket of the assembled engine to maintain a tension against the sleeves from the top to ensure a seal at the two machined surfaces described. The cylinder head gaskets are manufactured with a metal compression seal ring that is mated to the tops of the sleeves and these compression seal rings have a designed, calculated "crush" that upon assembly, ensure a permanent seal between the high temperature and pressure combustion gases, and the separate coolant and oil circulation passages of the assembled cylinder block and heads. It is important to note that the tops of the sleeves of the Freelander engine are designed to be flush with the head gasket surface of the cylinder block when assembled so that the head gasket will perform it's purpose of sealing effectively.

 

Incidence of Engine Failure

 

Many head gasket failures have been reported on the Freelander engine on the vehicle and it has been determined that this has been commonly caused by a condition where a cylinder sleeve (or sleeves) has "dropped" in the engine block (meaning that the top of the sleeve has moved below flush with the head gasket surface of the block). The condition occurred often enough that Land Rover issued a bulletin (Technical Bulletin #0036, dated June 16, 2004) for it's dealership technicians to provide a process for inspection and evaluation when a vehicle came in for repair. Though this bulletin also addresses an overheat condition diagnosis and repair, engine overheating often accompanies head gasket failure. The head gasket would have failed primarily because the tension of the crushed compression seal ring would be compromised as the sleeve moved lower into the block and away from the cylinder head, ultimately allowing coolant intrusion into the combustion chamber and combustion gases into the cooling system. This loss of tension against a cylinder sleeve would also compromise the sealing effectiveness of the aforementioned machined surfaces of the sleeve and cylinder block and allow coolant intrusion into the crankcase and engine oil, and thus causing catastrophic engine failure as the lubricating qualities of the engine oil are severely diminished when antifreeze coolant is mixed with it. 

 

Mechanism and dangers of engine failure

This would explain another common concern with the Freelander engine where the engines have seized (locked up), often times while driving. The reason that the sleeves drop in the block seems to be apparent and easy to understand. There are two basic principles at work in this issue. First, there is a significant difference in the thermal properties of steel and aluminum, and second, the steel cylinder sleeves are substantially harder than the alloy aluminum cylinder block they are fitted to.  Aluminum expands and contracts at a greater rate and degree than steel when heated and cooled.  In the normal life of an automotive engine there are an incredible number of these heating and cooling cycles- ie: cold start up to normal operating temperature and then cool down when shut off, occasional high work loads from trailer towing, climbing long grades in extreme weather conditions, etc. After enough of these cycles, the precision machined surfaces of the relatively soft aluminum cylinder block that relate to the fitment of the much harder steel sleeve would understandably be compromised as the aluminum is moving quicker and more than the steel in the process of thermal expansion and contraction. Add to this the fact that as the engine is running, pistons are moving up and down within the sleeves at a high rate of speed with some friction (normal-from the way that they are designed to fit within the sleeve), pushing up on the sleeve as the piston rises and then pulling down on the sleeve as the piston descends. This can effectively cause the hard steel sleeve to "hammer" against the machined surfaces within the bores of the softer aluminum cylinder block. Theses actions could be expected to cause the machined surfaces within the block to deteriorate and/or damaged to a point of failure.  This helps to explain why the sleeves drop in the cylinder block, causing head gasket failure and even catastrophic engine failure.  If this occurs in traffic, mechanical features such power braking will not function.  Stopping and maneuvering the vehicle particularly in traffic become a serious problem, and the condition poses dangers to the driver, occupants, and other vehicles. 

                                          

 

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