Low Coolant Indication after replacing the radiator.
 

Low Coolant Indication after replacing the radiator. The overflow tank is fine. I am beginning to wonder if it isn't the heater core. I have an XK8 that left the factory in September 1999. (2000 model year).

A little help for an old Yankee Sailor in the Colonies?

The coolant level indicator is in the side of the expansion tank ..often it moves out of place ..pull it out and glue it back in

Overflow tank
 

Check out tank behind right front tire inner fender
needs to be 1/2 full

The sensor is in the expansion tank not the overflow tank....its moved from its mounting.

Hi, although it's obvious, check that you've connected the sensor located under the expansion tank. Try moving the float ring inside with your finger (it might have stuck when you drained the tank and isn't rising). After replacing the expansion tank, I had the same error; it turned out to be the connector, which wasn't making good contact. I cut off the old one and spliced ​​in a new one.

Echo Echo

When I put more 50/50 coolant into the overflow tank, the light goes off. I drove a while, and the light came back on again. I refilled the overflow tank and let the system cool down. The light has yet to re-illuminate.

may have had air in your system so it might not really have been full after you replaced the radiator

just so we are all using the same terminology: when you say “overflow tank” are you referring to the tank with the low level sensor ? If so, I believe Jaguar is calling that an “expansion” tank.

the overflow tank, as previously mentioned, is behind the passenger side wheel liner (USA cars).

Z

I filled the tank that is mounted atop the engine compartment (it sits in front of the driver's side) on two different occasions. It appears the problem may have resolved itself. We'll see.

p.s. I had the transmission professionally removed/replaced with a used transmission.

Well...
 

I am unable to reach the expansion tank. The Low Coolant light and readout reappeared. As soon as I put more coolant in the upper (overflow) tank, the light and readout, once again, disappear.

On the 20th, I will have an oxygen sensor (B bank upstream Engine Code P1647) replaced. I'll see what my mechanic has to say about the Low Coolant Light and readout problem.

You have them mislabeled .


The upper tank, the one in the engine bay is called the expansion tank.


The one being the wheel liner on the other side of the car is the overflow tank.

I'll have Ed (of Consolidated Auto Works, Portland, OR) look at the overflow tank and tell him what is taking place. I am almost certain it shouldn't be a huge problem to rectify the situation.

If the cap on the top expansion tank is leaking you will have this problem . It also has a valve in it to work the overflow tank ...Get a new cap.

The expansion tank cap isn't leaking. It appears to be holding pressure within the system. I don't believe that this is the problem, but I'll look into it. I am not above rethinking the situation.

Thanks for the tip.

the cap has a RETURN VALVE from the overflow tank and and if this is faulty water does not return to the expansion tank !!!

Consolidated Auto Works will get to the bottom of this!
 

I'll be taking the XK8 to Consolidated Auto Works on the 20th. They promised to diagnose the "Low Coolant Light/Indicator" reading problem. They will do this while replacing the "B" bank upstream oxygen sensor. I believe the situation will be resolved. :)

Pistnbroke: Your diagnosis was spot on. The system is fine; the cap had failed. Baron (of Consolidated Auto Works) analyzed the problem and discovered the solution. The cap will be replaced, solving the issue/problem.

I’ve found that the caps are too easy to start to cross thread, and even though you back it off and try again, there’s some damage to the threads that seems to get worse over time.

the only way I can reliably get the cap to screw on straight from the beginning is to press down on the middle of it with my thumb whilst turning it with fingers. It always goes on straight that way and I’ve been using the same cap for about 4 years now (after going thru them in a year or less).

One thing that makes the cap a little problematic is that the o-rings swell up over time and “catch” while you are screwing it on. I’ve been replacing the o-rings every year or so, whenever the cap seems to go on stiffer. The difference in effort to put the cap on with a new o-ring set is obvious.

This cap is probably the original. The replacement will likely be sourced from Coventry, so...