How likely/common is it that a "blown" headgasget is caused by a faulty or partly clogged injector? (causing a to lean burn in a cylinder)

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I would say little to none. Age with millions of cylinder detonations would be the more likely cause. But a burnt valve or piston would be more a concern to me initially.

 

I'l agree with highhorse here. If an injector is clogged or not injecting correctly, then it is more likely to be something more severe. You'd have at least one burnt valve or a hole in your piston.

Dead head gaskets come mostly due to the engine overheating badly or faulty installation (like reusing it!).

Afaik these engines are only common to have a dead head gasket if: you up the boost too much on the XJR, drive it too long with no water or if it overheats in a jam and you don't take measures to cool it down (like tuning the AC off but the heating on full power etc.).

 

So, its kind of safe to say that a blown head gasget is quite likely to primarily happen due to the fact that the aluminium in a cylinder head somewhat "settle" itself a little bit over time?


Is it then more likely, that a burnt valve or a hole in the piston would happen before the headgasget "blows", if an faulty injector causing a to lean burn is the root cause?


Here in sweden i have my doubts regarding the quality of the fuel.. the 95 Octane we have here contains more alcohol than the 98 Octane. Someone mentioned to me that the Octane number itself might be correct as such, but the explosion burns with a much higher temperature with the 95 Octane due to the somwhat higher alcohol content.. casuing older engines to helplessly detonate at load, especially older carb engines, leading to severe overheat conditions witch in turn is "caused" by the cooling system not beeing dimensioned to be big enough to cool away the heat buildup..


I beleive that a modern computorised engine can tweak the fuel and ignitioncurve, and in that way can "camouflage" poor fuel quality.. and having the engines running with no margins to detonation what so ever..

A car manufacturer that make a carengine that wants to commit suicide if you end up in a trafficjam a hot day, wouldnt last to see the next summer..


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I run my 3.2l on E10 and E50 blends... Depending on my choice. Also the slower burning LPG is burned. My engine is totally healthy... If the engine is running lean, the lambda sonds would notice and put some codes in.

Question: why are you asking? Does your engine not run right? Do you have the 'reduced performance' message? Any check engine lights on? Any weird noises?

 

Btw., rüthe combustion temperature isn't the problem. The problem is the duration. Alcohol and petrol burn about the same speed. The temperature is actually within a few degrees the same. LPG burns colder but slower. Resulting in possible heat exposure to the exhaust valves. But even that is no problem for the AJ26.

 

Greatful for the awnsers! The reason i ponder over this is that i have the chance to buy an cheap 00 XKR with an blown headgasget.. trying to put togeather an partslist-cost-estimation... ... i need to get a feeling for what might have causeed it..

My brothers 98 Daimler had started to push cold water from coolingsystem, but in that case, since we caught it early, managed to postpone the inevetible with two cans of "Barleaks"

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If the head gasket is dead, then it isn't really a hard job... The heads can be done with the engine in the car (other cars need the engine out).

 

On my 2000 XJR the cost to replace head gaskets including related work and other parts was more or less about 4500,- euros.

 

I assume that was a gasket failure that led to additional machining and parts replacing?

 

On mine? Yes, cylinder heads need to be milled in any case. Guide seals were replaced and valves lapped. Valley hoses and water pump and thermostat replaced etc. My engine was replaced already earlier and had latest versions of timing components.

Shop was very clear on that they would only use later type metal type head gaskets and nothing else.

 

I believe there is some material degredation in the gasket material by the water coolant that causes a type of rot that let's water to the fire ring.
if you change them, use the MLS gaskets from the 4.2. The ones for a Landover are the same, but often cheaper. New head bolts too. Again, the Landrover bolts are much cheaper, but use RIBE drive and not 13mm head. Bolts are torque to yield. Should do chains and tensioner.
i did gaskets, bolts, chains, seals, intake and exhaust gaskets, valley hoses for USD 500. Was very obvious where the gasket had failed. Did not machine heads, and all has been good last 5000 miles. Did not even need timing tools, left the timing grears bolted to the cam shafts. Only caution is that the crank gears have to be in correct alignment as they can be placed 1/2 tooth off, and the crank bolt is very tight, very. ..