I had the coolant drained, flushed and the thermostat replaced. STILL SAME PROBLEM!

The car will cool considerably when descending a steep hill. Our outside temp. here is around 50 degrees F ; lower at night.

What could be causing the decrease in temp? The old thermostat was said to be stuck slightly open. the water pump was judged to be good.All hoses are open and clean.

Also, had the car engine stop completely with the readout saying "stability control failure" and engine failure. Wait a couple of minutes , restart it, it runs beautifully.

Any suggestions????

 

Turn off your AC and check the electric fans in front, if your car is cool they should not be running. And get those P codes.

 

If the engine is getting warm and is running well and you have coolant with a recent replacement of the thermostat I would be checking the integrity of the coolant temperature indication. Get a digital temperature probe and check the temperature at the thermostat housing and see what you come up with. The thermostat, water pump radiator and fan system are designed to maintain and reduce the temperature of the engine that is caused by friction. I know you replaced the temperature sensor but check the rest of the temperature indication stuff.

 

I finally drove the car more than 10 miles today. The same condition exists as before. No fans are running. At idle or stopped for traffic light or in town, the temp. goes to the middle. Head out to the highway , within minutes, the coolant temp. drops to the 1/4 mark. Something is causing the coolant to cool without the need of a thermostat????

What is the purpose of the coolant temp. sensor? Is it to maintain constant temp? If so, Mine is bad as the code originally read. How do I test it or is it reasonably priced to just replace it?

 

Sorry ...I also checked the codes again since the "stability control failure" light came up. No codes at all or any to read. Did it before and after the ride this AM

 

I agree with Gus that you should verify the temperature.

The themostat on your car is installed with a rubber gasket around the rim. If this is missing on the original and the replacement, it could be a cause of overcooling.

 

Wed. I have appt. to go in and have the thermostat retested. It is anew Jaguar product. I also ordered a new coolant sensor and will install that at the same time.

Jag dealer thinks it is a bad thermostat staying open from particles that may be in the coolant. Guess a well as mine.

 

I am having a similar issue. The amber engine light came on and will not go off. Went to advance auto and they checked the codes and p0128 came up. Does this also call for a thermostat replacement? I looked at some of the other threads and the placement of the thermostat looks pretty easy to get to even for a novice mech such as myself. What kind of tools will I need to replace the thermostat if I need to? Any recommendation on best replacement? Thanks as always for any and all help!!

 

Before you replace anything see if you can get the operating temperature of the engine. You can do this by using a Laser Temp gun like this Non-Contact Infrared Laser Thermometer Not knowing the symptoms you are experiencing you need to check first. As for changing the probe it is a simple process.

 

On your 2005, code P0128 is also a coolant thermostat range / performance fault. It could be either Thermostat or ECT sensor but is more likely to be Thermostat.

A simple job for the novice mech. Here's the procedure from JTIS:

JTIS - 2005 XKR Thermostat.pdf

Can be done without draining the cooling system and then topping up afterwards.

One thing that must be avoided is spilling coolant on the Serpentine Belt. It will start to squeak and the only solution becomes a replacement belt.

I'll leave it to US based members to advise on the best source for a Thermostat.

Graham

 

I had the third thermostat installed today. The one that was in was open about 1/8 inch! New Jaguar thermostat that costs $90.00 was defective. They replaced the thermostat with yet another Jag one; credited the labor and "We are sorry". Drove about 10 miles or so, seems to work perfectly.

BTW, we tried to compare A&A, National auto and Auto zone.....they were $22-34 dollars , but none fit for various reasons. Had to buy the Jag unit.

 

Wow, glad you got it sorted. It still acted like the thermostat was stuck open, but it was a brand-new replacement. Figured it had to be something else... wrong, lesson learned I guess!

 

What is most remarkable is that all of the aftermarket suppliers delivered the WRONG thermostat! They looked alike but did not function properly. The major difference is the "bleed" pin and the location (at least visually). The other differences , if any , are internal but beware....much labor and time w/inferior parts.

BTW, I dislike dealing w/Jag dealers for service or parts.

 

This forum has several parts sponsors and I frequent Motorcarsltd.com for my parts. If for any reason I need to go to the dealership I tell them the price I can get the part for elsewhere and they work with me on that.