Friday, February 28, 2014

Jaguar XK-8 Road Report

I have now had my latest indulgence, a ’99 Jaguar XK-8 for two months now so here’s what I’ve learned.

1. The Jaguar XK-8 is a luxury car. Prior to 2004 it isn’t really a sports car. Sure it has 2 seats and a convertible top, but a sports car shouldn’t weigh 2 tons, or if it does, it should have enough horsepower to move itself at a respectable rate.. The ’96-99 series has all the quirks a brand new vehicle is prone to, plus low horsepower and high weight. For ’00 to ’03 the aluminum engine got iron sleeves and a big boost in reliability. ’04 and up the car got a slightly larger engine with 100 extra horsepower, and an all aluminum body which shaved 500 pounds off the weight. Now we’re talking.

2. Everything in the car works with a small electric motor to drive it. This includes the door locks. There’s something under the hood that hums into position when I put the key in, and hums back to a rest position when I take the key out. I haven’t found out what it is yet.

3. The heater is fairly conventional except that it has its own motor to circulate the hot water. The pump on the motor evidently can’t handle this.

4. The convertible top is hydraulically actuated, including the latch above the windscreen. The hoses are plastic and move slightly when the pump is running. This causes some wear between the hoses which, over time, can rub a hole in the lines. The cure is a separator to hold the tubes apart. The lines are connected to the cylinders with QD connectors and O-rings. The O-rings are good for 50-70K miles before they begin to weep. Mine are due.

5. The electronics in the car are sensitive to fluctuations in battery voltage. The clever module that runs the windows down about ½” when you open a door, and runs them back up when you close it begins to fail when the battery voltage gets down to 11.5 volts. The windows go down, but don’t go back up. This is a nuisance when parking the car. The window needs to go down because it normally seats into a recess in the convertible top. This makes for a nice quiet ride, but in winter, ice can form on the drivers side window which prevents the window from going down. This makes getting the door open very difficult, so remember to scrape the ice from the side window before trying to get in.

6. The headlights can be set to come on when the car judges it necessary. Likewise dimming on the rear view mirror.

7. Owing to what was described as a “software glitch”, if you start the car from cold, and run it for less than about 2 minutes, say to move it up the drive after washing it, then shut it off, the “cold start” mode remains engaged and the fuel injectors remain open, draining the contents of the upper fuel line into the engine, effectively flooding it. For the first couple of days after you’ve committed this sin, the engine will not start. Period. When it does start, if there is any excess fuel in the engine, the engine will knock a bit, causing the knock sensor to send an error code to the engine. To correct this, all the spark plugs must be removed and the engine cranked with the gas pedal to the floor (which shuts off the fuel flow while you’re cranking!) until the engine is dried out. Alternatively you can let the car sit for 5 days and the excess fuel will drain/dry on its own. Mostly.

8. When you get certain error codes, like the knock sensor one mentioned above, you also get a “performance restricted” notification. What this means is that the ECU has limited the engine to 3000 rpm and floorboarding the throttle will not speed the car up past about 30 mph no matter how fast the traffic is bearing down on you from behind since at full throttle the tranny won’t shift until you get to 4000 rpm. OTOH, if you let off the gas, the tranny will complete the up shifts and allow you to reach freeway speeds. Just not right away.

9. The 17” low profile tires need to be inflated to 45 psi to get them to fully seat on the rims. It says so on the tires. What it does not say is that they should be run at 32 psi and unless you tell the tire monkeys this, you’ll drive off with your tires at 45. Great gas mileage, lousy traction. The folks I bought the car from were unaware of this.

10. The big items on this one are the rocker cover gaskets and timing chain tensioners. The gaskets are O-rings carefully selected to shrink slightly with age allowing a very small bit of oil to seep down onto the exhaust manifold. When you stop, the odor of burning oil permeates the car. The replacements, I’m told, are slightly larger and don’t have this problem. The chain tensioners turned out to be made of a plastic that degrades in the presence of hot oil such as you might fine inside an engine. Jaguar (Ford) has known about this for a while, but still sells the original plastic tensioners as replacements at the dealerships. Independent shops have metal replacements which they assure me will last indefinitely.

11. The car does fine on snow and ice, even better if the tires are at 32 PSI. The Automatic Stability Control kicks in if you begin to lose traction, reducing the engine output significantly. This usually happens when the steering wheel is turned slightly which blocks your view of the warning display, which helps keep you calm.

12. The car gets 20-22 mpg in town and 25-27 on the highway. That’s enough better than the pickup to make it slightly cheaper to drive, even with premium gas.

13. Parts and repair work are expensive. I presume that most Jaguar owners die of ulcers or heart failure from wondering WHAT WAS THAT NOI$E!

All cars come with quirks, some more significant than others. So far I’m liking the car even while not looking forward to doing the mechanical maintenance this summer. This is not my first British sports car by a long stretch, and while it is an order of magnitude better than any I've had before, my position that they are the most fun you can have driving when they work is unchanged.  


Anonymous said...

"even with premium gas."

I thought that at Colorado's elevations, you could get away with using a lower-octane fuel.

Billll said...

The government thinks you can, so "premium" around here is 91 octane. What we used to call "regular" back in the day.

Anonymous said...

Regarding #3, most European cars have heater control valves or pumps that only let heated coolant into the heater core when heat is demanded. BMWs since the early '80s have a thermostatic valve in front of the firewall that controls coolant flow to the heater. When you're starting a cold engine you want it to come up to temperature quickly for emissions reasons so modern BMWs have an electric pump that does not circulate coolant to the radiator until the engine temp reaches a set point, the pump supplying the heater core is programmed similarly.

In the summer you don't want to pump hot coolant into the air mixing box, that would just make the air conditioner work harder reducing available power and fuel efficiency.

More and more cars are using electric motors to move coolant, pressurize the brake fluid or steer the car. Compared to constantly turning a pump using an electric pump only when needed saves fuel, particularly in highway driving.