XJ40 engine… if normally serviced (changhe oil every year and water fluid every 2 years) how many km / miler can last without important issues… my xj 40 has 208.000 km and i would like to pass many years to come with her… i also have a daily Honda car… many people passed 500.000 km with honda engine even if it is a 25 years old model. What about the 3.2 and 4.0 liters 6 cilinder jaguar engines ?
in my opinion definitely more than the ‘moden’ engines.
its a big volume engine with little horsepower and no turbo.
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The rest of the car will fall apart long before the engine, so no problem.
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My xj40 4.0 has 230’000km on it. the biggest issue is mostly rust and electrical issues and water seals.
The engine has good compression on all cylinders, pretty even, however it shakes a bit in idle, but that might be a mixture issue…
Hope a new lambda sensor might help with that
oh and of course oil leaks here and there
I sold my old Sovereign with 186000 miles on the clock and the engine was still running like a Rolex watch. The new owner who was a friend of mine took the mileage to > 250,000 before he scrapped the car due to terminal rust issues around the front and rear windows. It was a real pity because the engine was still faultless and as smooth as silk, same for the transmission and general running gear. If the servicing schedule is followed correctly and the cooling system maintained to pre-empt any overheating issues the engine is almost indestructible.
Nine went to 400.000 kmbefore rust terminally killed it. I guess that makes 250000 miles. Engine was going perfectly, on original head gasket.
My n has 301000 km on LPG and runs like new My oil pressure is over 4 bar at 800 rev s and still has its full power Oil after 6000 km as clean as new and no oil leaks
That 186K miles makes me feel good, I’m at 110K less than that and if all the ancillary and magic electrical things hang in there it should last the rest of my life. No serious rust issues worth worrying about and paint looks like new.
And it was using less than a pint of oil between 7500 mile oil changes at that mileage, still had the original head gasket and never lost a drop of coolant.
Gentleman …
My 1989 has 172,000 miles. I replaced the head gasket at around 150K and while the head was off had it it cleaned and resurfaced by a machine shop. All the original valves were still good so had them reground and lapped. Compression is like new. Still runs smooth as silk 
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