Ok I've been on this forum for years and I have yet another xk8 problem...if that's possible.
9 months ago I replaced my thermostat and the entire tower (housing) it sits in. Reason being cuz originally it's plastic. So I replaced it with a shiny aluminum one. Worked fine for the last 9 months. Then one day I found the large radiator hose was off and obviously as a result the coolant was low. So I put the hose back on and tightened it very well this time. Replaced coolant and was on my way. About 10 miles down the road my red coolant light comes back on but car is not hot. I see that just about a cup of coolant is gone. I fill it again and go. 10 miles later same thing happens like 2 more times. I don't know where this 1 cup is disappearing to. There's no leaks. I'm thinking pressure is building up cuz it's not circulating or thermostat is not opening up? Anyways, I drove one day and it got hot all the way to "h" & it shut off on freeway. I had it towed home and it hasn't started since.

 

Yikes.. You may be in for some tough repair bills, or a crap-load of work. Have you taken out the plugs yet? Do a compression check? coolant in the oil or vice versa?
Sorry for your trouble.. best of luck

 

The AJ27 engine does not have a 'fail-safe' shut down. If the engine stopped, it is because it has internal damage.

I have 2 abandoned XJ8s in my parking area at the shop because the radiator hose blew off and the driver was 'almost there' "I think I can make it!!!!!" Kept driving until the engine quit. The knock sensors look like little plastic melted puddles.

Looks like a replacement engine is in your future.

bob

 

Wish you the best of luck but knowing how the gauges work in these cars led me to install whitexkr's realgauge kit. I have worked off and on for 9 months to get my car to reliable driving conditions and don't want to lose it now.

 

Once refilled, the cooling system MUST be purged of air trapped in the engine or radiator. It's called "burping" the system. With trapped air no temp gauge will be accurate. The gauge relies on coolant at the sensor to read the temp. Does it crank over? Does the engine spin as normal? Does the oil smell burnt? Look under the oil fill cap. is there moisture residue on it?

 

Plenty of overheating events, both here and elsewhere, where temp gauge movement towards "hot" was not quick enough to warn driver in time. In your case, it ventured right to "H" and stopped. Major hose disconnection suggests massive coolant dump.

Sad to say it's hit the piggy bank time . . . yet another dead engine . . . yet another reminder for all, but especially new arrivals, to become fully informed of specific MY weaknesses, to check appropriately and regularly, and that ignoring repeated warnings of coolant loss, will lead to inevitable "blow off" that results in immediate overheating.

I don't intend this to sound callous but this is a well known weakness with well known consequences . . . and I come off last month's episode of having warned a new owner of a similar 4.0L who ignored repeated warnings of very brown, plastic t/c components that needed to be replaced . . . but when they let go only days later at high rpm, reducing his engine to a V4, could not restrain his anger at everything Jaguar.

Not suggesting this fits your case Debbie . . . I really do sympathize . . . but ultimately, a massive coolant dump followed by serious overheating is a sure formula for sad news.

Best wishes,

Ken

 

It turns over like normal, but doesn't start. It's been sitting for about 3 weeks and I've left it alone. Haven't done any checking of anything just yet. I'll do that this weekend and update. Thanks for all the responses. I had a feeling they wouldn't be good news. I'll find out for sure hopefully this weekend. Thanks again.....

 

Debbie, do the compression test. If you have any cylinders with low or zero compression the motor is done.

 

Thanks bobroy...you're the best. Clearly I'm not a mechanic, I'm just a girl that should never have had a jaguar. You've been very helpful, but doing a compression check is something we can do when I drop off the stereo. Lol.
I'll be getting that stereo to u soon. Wanna buy a car?

 

I might have a little free time today to look at it.

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