So I've been giving my Uncle's XK8 the 20 year (slow) treatment; new hoses, parts that may fail, etc. So I ordered a new (reproduction the sales rep called it) reservoir with sensor from SNG Barratt. I finally got around to installing and even though I purged the system as directed in the shop manual, heater on, etc., I'm still getting an Engine Coolant Low red light.

I took the car for multiple drives with the heater on full blast over the past 2 weeks, still getting it. So I finally got fed up and jumpered the wire and the light goes away. I KNOW I have the reservoir filled to the top as I can feel the float with my finger and it's all the way to the top. Plus this isn't my first rodeo with these as I've replaced and refilled the one on my XKR too many times to count.

Did I get a bad tank and sensor??? I want the sensor to be reliable for him when I give it back. Thanks!

-Scott

P.S. Also want to say, I'm not bashing SNG Barratt at all, they said the tank is under warranty and great customer service, just making sure I'm troubleshooting this correctly before I send it back, etc. If anyone has any idea of how to troubleshoot let me know. Like I said, I jumper the sensor connection on the harness side and the red Engine Coolant Low light goes away.

 

Could you easily test the float switch? Unplug the wire harness and measure continuity as you manually move the float.

gosh I changed my resivour 6 months ago, but I can't recall the connection/connector. I figured if you can short it, you can probably get easy enough access to read continuity.

hope it helps.
John

 

1. you KNOW the tank is full so the low warning is false
2. the warning light goes out if you jumper the connector

I think you've answered your own question about it being a bad sensor.

Graham

 

Thanks Graham, I agree, thanks for the confirmation. Wanted to make sure there wasn't anything else to try but it sounds like it's as simple as it's made out to be.

I'm going to measure the continuity of the bad and the new good one when it arrives.

You should be able to flip it over when empty and test across the terminals as the float should "fall" to the top when upside down.

 

Hi Scott,

i have had the very same issue recently with my new expansion tank bought from SnG, too. Cold engine and everything was fine, but after a few miles on the road the low coolant light popped up.
After beeing sure that the coolant level is o.k. i changed the level sensor with the old one, same behavior, after getting warm the warning light comes up.
To verify the malfunction i removed the new tank and put the old one in place and after that the low coolant light remains dark as it was supposed to do.
The culprit is the floater inside the tank. this sob sinks to the bottom of the tank as soon the temperature increases slightly, despite the tank is filled up to the neck.
I send the tank back to SnG with a failure description and got a new one within a few days. No further issues so far.

Hope this helps,

Fritz

 

Thanks Fritz,

That helps quite a bit. Same symptoms here as well, although mine never recovered after the first time and the light has stayed on permanently since.

Happened to be at a full fluid flush to so I was going crazy thinking I hadn't burped it correctly until I tested with a jumper wire.

Hopefully their supplier gets these sorted, but like I said they stood behind it and the new one should be here Wednesday.

-Scott