2nd thread on this ... still confused.

98 XJR keeps saying "engine coolant low". I thought it was a sensor, as it would say this when the expansion tank was 80% full. Last night I replaced the expansion tank and coolant level sensor, filled up the expansion tank to about 70% (to where the float is all the way up) - car still says "engine coolant low".

So if it's not my sensor, what is it? I'm reasonably sure that the car is not low on coolant. If I top it off to fill the exp. tank, the warning goes away.. but then coolant will drip a little from the overflow in the bumper until I lose enough coolant for the tank to be 80% full, and warning comes back.

Should that overflow in the bumper be full of coolant? Mine's about 30% full. Is it dripping coolant because there's too much in the system?

I'm confused, so any advise would be appreciated.

 

Ahh I had the same issue beginning of last year on my ole 98. I had the same issue. For me it was indeed the low coolant sensor. The housing for mine was completely shot and the sensor just fell out haha (cool huh got it like that . I bought a replacement sensor as well, no dice. Didn't change anything, "low coolant' still there 24/7. In fact, that new sensor is still in the bag right behind me. $54 ouch!

My mechanic put on old one and bypassed the sensor (don't ask) and tied it up, works great now. Not much help I guess, but I'd bet it was the sensor having issues bro.

 

The reservoir needs to be full to the top, the reservoir in the bumper has a overflow(open port) about 1/3 the way up. When cold the engine compartment reservoir needs to be completly full to the top. If you do it when hot or warm the level will drop turning on the light when cold. Then will useally go back out when back up to operating temp.

 

Well then, I guess I must have a coolant leak, b/c I kept filling the damn thing to the top every day or two. but........ when the car is running or shut off, no coolant drips down from anywhere ---- bone dry. It just seems to drip out for a second or 2 right when I shut the car off, from around the bumper reservoir area.
Why would it just leak out when I shut the car off? Shouldn't the bumper overflow just spit out coolant when there's too much coolant in the system? This one is driving me mad.

 

maybe it's not actually leaking out the way you think it is, I had a ford that had a small crack in the reservoir but it only leaked when it heated up so I never saw it drip or leak much, but on a long drive it would drain the tank. It was hard to find because it was a small leak and the hot engine evaporated the coolant so there was no sign of the leak unless you looked really close.

 

I've been getting the same message on my '98 XJR. It only happens when I drive the car 'hard' stays on for about 30-60 secs max and then goes off.

I took it to a Jag specialist and remember them saying something similar to what BRUTAL said earlier. They said nothing to worry about. But I don't like the idea of red warning lights showing up!

Coolant level is checked regularly and seems topped up. Should I be concerned about this?

 

How old is your coolant cap? If it can't hold sufficient pressure it will cause coolant to spit out as soon as it stops circulating, in this case from the overflow resevior (the path of least resistance). Also check your distribution pipe in front of the thermostat housing as those have a tendency to develop small leaks over time.