So I was able to replace the expansion tank with help from the forum. Now I have another related or non related issue, happened the first time while i was dealing with the clip connector to the tank...that is fixed. car runs perfectly and then all of a sudden....

Now I have another issue, after about 20 min of all types of driving the temp guage slowly climbs into the red, all the way to the light going on at the top, the car goes into limp mode and sticks in 2nd sort of on and off...the fans go on big time...but the car is not over heating, the tank is full up, the coolant is not going anyplace out of the car, no leaks, the top hose is firm and hot. it stays in this mode acting like it is overheating big time...but it's not.

then i let it sit, fans on full, they go off, eventually after cool down i drive it again, and it overheats(guarge climbs)....NO idiot light, no message.

wtf?????

 

It sounds like it is overheating.

But you've not quite seen the signs in the right place(s).

Maybe it's not circulating the hot water properly so isn't cooling it properly.

Be aware these engines do NOT cope well with overheating so fix it ASAP.

 

Have you checked the temperature with an OBDII reader?
That will give you an accurate reading.

 

It what is over heating, STOP driving it. The temp gauge is terrible, the car is over heating by the time it tells you. Get a real time gauge on it. Feel below the water pump, feel any dampness? If so the pump is going or gone which can cause you issues. The water pump is an easy job on this car.

 

Was the system correctly bled to remove pockets of air? Refer to the Workshop Manual for the correct procedure.

The temperature gauge does not register any changes between 86 C and 129 C, which is too late. Do not rely on the instrument cluster temperature gauge to determine if the engine is overheating.
Use a smart phone with Torque app and Bluetooth adapter to monitor coolant temperature.

 

To add on what the others have said: the engine is overheating, in spite of the fact that you are not feeling it to the touch. There is a reason for this, if the coolant is not circulating you will not be feeling it in certain places of the engine. You can tell by touching both radiator hoses and around the engine. If the thermostat is stuck closed, one of the hoses will be hot, and the other one cold. The temperature gauge on these cars is a dummy, meant to keep the original owner unaware of the normal fluctuations of the gauge. Unless you have the Real-Gauge installed, you can't trust what it displays.

• The first thing I would do (when the car is cold) is check the coolant and check the oil. Pray that neither is foamy, chocolate or coffee colored. If either is, you would be lucky if it only damaged the head gasket, if you're unlucky, you could have warped the heads.
• Now, assuming you dodged that bullet and no damage happened, what I would do immediately is change the thermostat which is a $14 dollar part from Pep Boys.
• I would also change the water pump, which can be had for about $50 - $100 depending on the brand. To replace the pump, you are going to have to remove the air intake filter box, and the serpentine belt. It might be a good time to inspect its condition. If it already made a chirp, shriek, or squeak, if the rubber has tears in it, it would be wise to change it and the pulleys as well. They're cheap enough and found damn near everywhere. If coolant ever leaked on them, you must replace this belts. It's an easy job.
• To swap these parts, it is best to drain the coolant out of the system. You will need a large (about 2 or 3 foot long) flat head screw driver to unscrew the radiator drain plug, which is made of rubber.
• Refill with new coolant (or filter the old one if you had it flushed recently; a blanket, a bucket and some cord to tie them together will be a good makeshift filter).
• Properly burp the system and keep an eye on the coolant level for the next week or so of driving.
• You will have to add some more after a few drives.

After an overheat, the thermostat is almost certainly toast. For the t-stat, I like the Stant brand. Maybe someone can chime in on the best water pump to buy. If either of those components failed, you may not have coolant circulating through the engine, which = overheating. The thermostat could fail by staying either open or closed, in your case, it could likely be closed. If the water pump failed, without leaking, then I would bet the plastic vanes have broken off.

I have attached a guide on replacing the thermostat and flushing the coolant system. I hope you didn't incur major engine damage, because if you haven't, this is an easy fix.

 

I agree with all the advice NOT TO IGNORE overheating - it is a Jaguar V8 ENGINE KILLER. Also that the temperature gauge is next to useless.

However, IF you are right that the engine is not actually overheating, then it is likely to be a faulty temperature sensor BUT I certainly would not delay getting Torque or equivalent on the vehicle to determine actual temperature before making any assumptions.

Graham

 

You may have a bad thermostat or a water pump with a damaged impeller.

If you replace the thermostat, I suggest getting one from a dealer. This thermostat has a bypass valve and a wiggler valve on it which it needs. Aftermarket thermostats are all over the place, don't get aftermarket for this car, it is so not worth it. Even if the thermostat has the bypass valve, it is hard to tell if it will seal to the water passage correctly unless it is OEM. If there is no bypass valve, the water flow will go around through the bypass and overheat the engine. The wiggler valve lets air bubbles pass through the thermostat to prevent air lock.

The water pumps had some bad plastic impellers on them that shed blades, you may have this problem.

 

I guess what you all don't know is that I replaced the water pump, belt, thermostat, coolant about 5,000 miles ago, no issues after that. it would be a stellar coincidence if one of those went bad intermittently at the same time i had the plug issue with the expansion tank , the problem is intermittent, not like a usual over heating.

i start car let it idle for 5 min to see what happens...it's all ok, temp is rising just fine. go for a ride, maybe 20 min...and it happens. goes from normal to hot in 10 seconds, stay there, fans working...till i shut it down, wait and it's fine then over again.

if it were a sensor it would always do it, immediately...same with bad components of cooling system...i think it maybe the burping thing, i will see what i can do, and yes not drive it till its ok....

i had to remove expansion tank to replace it, that let coolant out, i tried to burp it while hot, that was also a problem and did not work...so ill try another technique. thanks all of you for your input, still no fix. how do you burp it completely?

there must be a way to burp this thing well, i don't have a workshop manual and i have looked through the pages of adobe with no avail.

 

Could be a clogged radiator. This can be caused by mixing orange and green coolant.

 

What I do is to start the car cold with the expansion tank cap open. If the level is too high, it may overflow. To prevent this, remove some coolant with a turkey baster. Then, as the engine is running, I squeeze the upper radiator hoses, and then the lower radiator hose, repeatedly. You should keep an eye on the coolant level as it may either rise or drop. Keep doing this until the system literally doesn't burp anymore. Is the coolant level low? If yes, add more coolant and keep burping. Do this until the coolant level drops no more.


Oh, one more thing, if you don't allow the car to get to normal operating temperatures, the thermostat may not have opened yet, meaning that there may be air left in the system. However, if the coolant is completely topped off, as it heats up the coolant level will rise and may overflow. When I remove coolant with the turkey baster, I usually leave enough in so that only ¾ of the expansion tank are full.

 

your method worked, my baster came apart at the wrong time, messy and it worked, i could see small bubbles and then no bubbles.
when it started to over flow i removed, and i removed before hand as well... eventually there were no more bubbles, just hot coolant...and i had the heater on full at the same time, that's also a cue when the heater is working on hot for a few moments...the coolant is circulating fully.

eventually on the drive i got a low coolant level. i then let it cool a bit, opened the tank and put more in so the level when warm is about an inch from the top, will check it again if there is an issue.

Giandaniel...i want to thank you again for your excellent advice....all i can say is so far so good....

 

Coolant level should be right to the neck when cold.

 

Well still have the same issue...so I have purchased a large funnel kit to bleed the system, not expensive and I will try again, also will jack up front of car in front which may help. Thanks again to all of you, so far no fix....what I could use is someone with the EXACT SAME ISSUE who has fixed it....

 

Is there anyone? Very possibly no.

 

These are the steps I followed to repair the cooling system on a car that had been sitting for years:

1) Do you have the correct expansion tank fitted, or made adjustments in the lines so that a different model year expansion tank will fit?
See TSB 303-15.
On 1998 and later expansion tanks, one of the expansion tank hose fittings is plugged because there is no functioning bleed line (I believe it is the rear hose fitting, but the diagram is a bit confusing). Easy to visually check. The open line goes to the thermostat.
2) Flip the thermostat as suggested earlier.
3) Flush the radiator.

 

thank you all again for your attention and advise on this matter. I have parked the car for now, coolant level good, no overheating for several miles, the expansion tank is fitted properly...i believe at this time with no further testing that it must be a very small blown head gasket leak, which after warming up lets exhaust into the cooling system causing bubbles...at any rate the car can sit, i have a battery tender and after year end i will most likely sell it, nice car, been a real experience, only 46,000 miles of which i put 6,000 in almost two years....i do appreciate these cars for what they are, a very fine good handling luxury touring car/convertible.
smooth and great handling, smooth and powerful engine, lots of features and great looks....but, but, they can be very sensitive to little things that are not easy to fix, fiddly at best...but worth it ....i have not seen another one this color either, eggplant.

 

There are a number of tests for this working theory. Search "Combustion Leak Tester" on amazon for a bunch of options. It looks like a setup where the exhaust present in the coolant is made to go through a fluid that changes color if hydrocarbons are present. I believe there are cheaper strips as well at the parts store.

 

i just tried the head gasket blue liquid with squeeze bulb test, three times, no change in fluid color and no overheating with over 20 min of idle and fans turning on..

 

Check the radiator. I agree with JimmyL. I had a similar issue with a Jeep Cherokee that drove me nuts, When the plastic tank blew on the radiator in the boonies120 miles from home I could see the problem through the hole.