Hello all! just encountering my 2nd issue with my x-type, just some background info on my jag, its a 03 with 113k miles, just bought the jag from Chicago and drove it 3.5 hrs north back to my home in Wisconsin, car ran great while on the way back and didn't encounter any issues until now, i was driving about 45mph and noticed the temp started to go up past half mark, so i quickly turned the heat to full blast and highest temp and it went back to a little under half the rest of the way home, however the other night when i was on the Highway, i got up to about 70 and it crept up past 3/4 and i pulled off and shut the car down just as the light came on, sat for like a second, turned the car back to on but didnt start it, temp was going down and back to normal, turned the car back on and was all great again, started driving and had no more issues the last 2 miles of my journey, what would be the issue? Thermostat possibly? it has not over heated while in idle at all just while id be moving. Thanks In advance!

 

Sounds like a thermostat to me. It's an easy and cheap fix to try.

 

That's what I was guessing as well. Thanks. Another question, why would my aux fan be running about 10 mins after the car was shut off? I haven't driven it hard or anythig and it always shuts off just a bit after the car is off and its been like 10 degrees or less outside lately, does temp play a factor in its excessive running ?

 

afstud, like AVT said, odds are it is your thermostat is stuck closed. But, if you also have the coolant system drained, you may want to spend a few extra bucks and replace the water pump too. It is a super easy thing to replace. You will find replacing the thermostat more difficult than replacing the water pump. If that doesn't fix your issue, then you have a problem internal to the radiator (channels are blocked and you are not getting sufficient cooling surface area).

 

yea i will probably do both at the same time, i normally try to do it like that but moneys tight at the moment, but well get it replaced, but what do you think about my cooling fan issues? It runs for a bit when the car is shut off, and its been 10 degrees or less outside the past couple days so idk why it would even be running at all....

 

If you don't have flow through the radiator, regardless of the temp outside, the motor will overheat. It may take longer, but it will still overheat. if you are getting plenty of heat inside the cab of the car, then you can probably pass on the water pump and just go with the thermostat.

Not to ask a silly question, but, how is the level inside the overflow bottle? If that is low, you can have an overheating issue too. I have seen this numerous times here too. If your level is low, the water pump will cavitate and not flow through the block/radiator, leading to an overheat condition. Normally this is caused by either a bad water pump bearing (leaking out through the seal) or more commonly with a cracked fitting on the overflow bottle (look at the fitting near the firewall for a solid white line running around it).

 

There are no coolant leaks that I can see and the bottle is full, have not checked it at operating temp yet, and I looked at the water pump and it looks new compared to everything else so ill still replace the thermostat, when it comes in and report any changes. Where's instruction on bleeding the system?

 

afstud, I do not follow any of the special bleeding instructions that have been talked about. There is a tube that runs off of the back of the engine that is at the high point in the block and it flows directly to the overflow bottle. Fill the system up with the engine off, start the engine and let it idle (with the cap removed). Add coolant as it gets low in the overflow bottle. Once level stabilizes, put the cap on and go for a short drive. If you feel it necessary, you can use the J-gate to force the tranny into a specific gear. That way you can force the motor to rev up to a higher RPM (say 4-5,000 RPM). This will help force the air bubbles that may still be trapped around to the overflow bottle. Park the car, let cool, then top off the overflow bottle to the "cool" line. You are good.

 

thanks Thermo! really appreciate all your help, maybe you can help me clarify one of my other issues, the humming noise at 30mph and up, and the odd whistle noise when i decelerate under 30 ? i added fluid to the TC it was dry and gross but the noise is still there.

 

HUmming noise is probably the prop shaft bearing. A grease gun with a needle attachment will fix that. As for the whistle noise when you are decellerating, can't help you with that.

 

and to answer your question about the cooling fans....i think that's normal...right Thermo?

 

afstud/iownme, yes, the fans will run for a short period after the car is turned off if the coolant temperature is high enough. The trick is that they should only run for say 30 seconds or so. If they are running for a long time, then that is indicating that you have other issues going on.

 

Thermo, is it possible/probable that his fan module is the culprit?

 

iownme, it is not the fans. The amount of air flowing through the grill openings at 70 mph is a few times that what the fans pull. So, unless there is a blockage between the grille and the radiator, at speed, you have plenty of air flow whether the fans are running or not.

 

even coming from the highway the fans were running but that was last week when it was below 10 degrees, now that the temps have been 20-30+ its all normal and the fans have not ran after the car was turned off and i drive a lot everyday, city and highway and has not even tried to over heat so i think the extreme temps had something to do with it and causing the thermostat to mess up or something.. idk but its been great since.