I have an odd situation and I'm looking for some insight.

I drove my '04 XJR to work on Friday and everything was fine. I got out of work Friday night (midnight) and it wouldn't turn over. Tried jumping it and that didn't help. Gave up and got a ride home. Went back the next day when it was warmer and it still wouldn't crank. Plenty of power going to the battery through the jump leads, but it won't turn. After that I figured it was neither the batter nor the cold and had it towed to the shop. Figured that the starter motor had died.

I just got off the phone with them and yes, the starter motor had died. However, the reason it had died is that the cylinders were full of water. Not coolant, just water. They're smart guys and have been working on European performance cars for a long time but no one can figure out how the water got in there. The air filter was completely dry and the weather that day had been cold and clear. The only thing I can think of is that with the cold, dropping 20 degrees that night, water vapor condensed in the cylinders, but I can't imagine there being enough water in the air for that to happen.

They drained the oil (and water), changed the starter, put new oil in, and it started right up and runs well.
So, how did the water get in there? Any thoughts?

 

See this thread: https://www.jaguarforums.com/forum/x...engine-110573/

 

It's not condensation in the cylinders, it's moisture in the air condensing and freezing on the cooled bits in the intercoolers. It happens a lot in the US & Canada in winter months on morning commuter runs. The air has a high relative humidity having cooled over night, and the car is running with small throttle openings and so is pulling a fair vacuum (the S/C is effectively short circuited by the by-pass which is wide open when the thottle is at small openings); it's the same process by which clouds are formed when moist air rises in the atmosphere and the pressure falls.

The moisture condenses out (if it isn't already in the form of a fog) and freezes on the coldest place it finds which is the cooled bits of the intercooler, which will be at ambient.

When the engine stops and the intercooler slowly warms up the ice melts and the water falls into the intake manifold(s) and into any cylinders where the inlet valves are open. If you notice the intercoolers are virtually vertically above the inlet manifolds.

One solution might (might) be to switch off (would need a switch fitting) the S/C cooling pump on short journeys on cold mornings when the car's 'performance' isn't being used.

 

And this one https://www.jaguarforums.com/forum/s...2/#post1588710

 

I think if Jag had been aware of the problem at the outset they would have put some sort of thermostat in the intercooler loop and brought some warm water from the engine coolant into the intercooler coolant loop to raise the inlet temperature to around 0C/32F.

It would be interesting to know whether the latest S/C engines are differently designed.

 

I doubt that the SC was modified in the X358's and XK's 150 or in the latest 4.2 SC's in the first XF's.
Maybe in the 5.0 SC's, to be checked.

Isn't this "faulted" design of the intercooler for use at very low temps an unwanted consequence of the fact that, in order to improve performance of the engine, you generally look for injecting air cooled as much as possible through the SC?

 

Wow, seems to be an epidemic of hydrolocked supercharged engines and it's only the second day of winter!

 

I doubt there would be a problem if the intercoolers weren't directly above the inlet manifold. If they were to one side with the take off at or near the top then any melting water would go to the bottom where it would be more likely just lie and slowly evaporate.

Either way, yea, dumb design, in retrospect.