Inspected the hoses from above as best one can & the hoses all seemed "like new"; no signs of being brittle or cracked, etc. So, unless further tests indicate otherwise, I will bleed the system & fill with coolant & button her up and hope for the best.

I cranked her and she sounds just like she always has & there were no signs of leaking after running for 15 minutes. I am doing something else for an hour; then, I will check water level & run her for 30 minutes.

Assuming she is fixed, at this point, my theory:

The water level sensor came out. I say this because I had received no messages re water level etc. & it all seemed to happen, based on the large volume of water as I parked her, all of a sudden. After I installed the new water sensor & tank & before I added water, I turned on the ignition & got a "low water level" message.

I hope that my next & last post on this subject will say that all is fixed. We'll see.

Thanks for all the help.

 

OK, after running for 20 minutes with Climate off, noticed the heat gauge on the dash was at about 3/4; raced the engine & it went back to the 1/2 mark. When I switched engine off, the cooling fan continued to run for awhile. Without opening the coolant reservoir, can see that the fluid color inside the tank is now pink which, I think, indicates that the thermostat opened.

I suspect that there is very little coolant vs. water in the system. Would water in the system vs. coolant cause the engine to run at a higher temp; hence, the need for the fans to run after the engine is switched off? If so, I am inclined bleed & refill with coolant since the system shows no indication of a leak.

Since, when the problem first occurred, there was obviously a major leak, I decided not to do a pressure test. Instead, I will check level daily until I am comfortable with the fix.

Any observations or suggestions will be greatly appreciated.

 

Hello.. I'm no expert but when the temp gauge reaches the 3/4 mark you better shut the engine off. The temp gauge will basically stay at the half way mark for a wide temp range and will only reach the 3/4 mark when the temp hits a very high mark, Sorry I'm just speaking off the top of my head.

I'd make sure your system is bled correctly and don't disregard the pressure test.

Good Luck!

 

Thanks, Mpasiuk. Nothing wrong with off the top of your head!

Plan to run again tomorrow only with the heat on high to get the heater coolant circulated. Then I plan to follow factory manual instructions for bleeding & refilling kindly provided above by the ineffable Super Mod.

I do plan to pressure test. However, doing so is complicated by a small water pump leak. This was detected some 6 years ago & the dealer was afraid a bolt would break & he didn't want to risk it. So, I took it to my favorite Jag mechanic & when he called to say he was concerned that a bolt would break, I said try to get it off & of course, it broke. His man with little hands who could fix it went to Europe with a local hooker & never returned. He said: "If it were me, I'd leave it alone & check the level ocassionally.". I have checked the level every month for over 6 yrs. & it loses 1/4 cup per month. Subsequently, I have the cleanest coolant in town.

If I had smaller hands, I would try to extract the broken bolt & replace the pump.

 

From my experience, the fan running after the engine is off is normal. I've had other cars do this too. Any reason you didn't use pre-mixed coolant to eliminate the guessing game?

 

Thanks, Kinarsh. Now that I have fixed the leak, I will bleed & fill with the pre-mixed coolant later today.

 

It just dawned on me that I have not changed the thermostat! Before I refill with coolant, will do that since at 19 years of age, it is a miracle that it hasn't malfunctioned.

If not in stock, may take a while to get. Will give me time to study & remove old one.

When I finish with this, will endeavor to summarize.

 

Go to your local parts store and borrow a pressure tester. Think cap 22 is correct fitting. Put 15 pounds on coolant system and let sit for an hour. Your small water pump leak will skew the results. But should hold well if not running.
Beg, borrow, or steal a scanner. When running the leak free engine monitor coolant temperature. If you see over 95C turn off and let it cool down. The gauge s really only is here to tell you the engine has overheated. Too late.
The temperature gauge operation is a European thing. Many cars have a gauge the only tells you cold, normal, and cooked engine.

 

Thanks, Panelhead. I have a scanner & will use for temp reading. I'm reasonably sure that the leak was from the Coolant Reservoir which I have replaced. Ran her for 20 minutes this morning & everything seems fine.

Plan is to drain the system; replace the thermostat; refill & test again by running, mainly to check the thermostat housing for leaks. Then, after she cools, will do the pressure test as per your instructions. Assuming all good, will drain & fill with coolant. I will check every day for a while before putting the plastic covers back on.

While I'm at it, I'm tempted to dink with the radar under the front bumper to see if I can fix the Adaptive Cruise Control. But, maybe not.

 

Thank you all very much. With your help, mission accomplished! Drove her around for about 30 minutes. Temp gauge stayed right in the middle...

The only 2 things that I did that I ordinarily wouldn't have is that I bought the thermostat from O'Reilly & I bought the O'Reilly Coolant for all cars. I was using the same coolant as Kiznarsh, but they've changed the label a bit & now Zerex Valvoline is recommending something purple for my car. So, I said, what the hey, we live in a moderate climate... I did mix it with the coolant I had been using to see if it would coagulate before I put it in the car. We'll see how it works out.

While I will monitor the coolant scenario carefully, I'm ready to ****** that radar from under the front bumper to see if I can divine anything to fix the ACC. Of course, I will review the many good threads...