Cooling fluid low message keeps coming up. Water pump, radiator and cooling level sensor all replaced. Light goes out but comes back on , what could be the problem?

 

Did you replace the reservoir and bleed/burp the system?

-dsd

 

Can you just bleed the system? The reservoir doesn't leak. Does it have to be replaced?

 

Hi Frank,
Key question - Are you having to add fluid? If so, does that (temporarily) overcome the problem?

 

I assume that you only replaced the sensor on the bottom of the reservoir. There is also a float inside the tank that tells the warning light when to go on or off. Over time, this float gets saturated and doesn't float as well anymore. That sets off the warning light.

Take the cap off the reservoir tank (when its cold) and reach inside with a long screwdriver and you can lift up the float. If that turns off the light, you need a new tank.

BTW, tons of threads on this issue in the forum. So happy searching.

 

if you just did all those repairs and there are no leaks it could take several drive cycles to get the level to level out. When you open the resivor, taking the cap off, when cold the fluid should come up to just at the bottom opening. You may have to top it off top that point a few times. If it stays at that level and you still get the light, may be time to replace the whole resivor. Dont mess with just the sensor do the unit whole tank as you prob will see it leaking down the road anyway

 

Thank you so much for your information. I just checked the level and it did go down some. I just bought the car and they topped it off the first time just before I bought it. Then the light went out. After driving 3 days it came back on today. I topped it off again. Maybe it will stop going down , if not I will replace the whole tank as you suggest. Thanks for your help. Frank

 

If it needs to be topped up repeatedly you have a leak and should have the system pressure tested.

 

+1 on pressure test!!!! If you have no visible signs of leakage under the car - my guess would be valley hoses or octopus hose

 

If you want to pressure test it yourself most of the car part stores will lend you the tool for free.

 

Yes, do not start 'replacing parts' until you have a pressure test and know where the leak(s) are. Leaks show up very easily under pressure. As others have pointed out you can do it yourself.

I ended up buying a Stant pressure tester and the necessary adaptors to fit all my cars. At first it seemed like a frivolous purchase, but after five years, I have used it much more often than I would have anticipated. In the long run saving a lot of time and money on replacing parts hoping to find the source of the leaks.

 

Frank, the tester sold by Harbor freight has te proper adapter for the Jag. It's not cheap, but worth having around.

 

+1

There are many places it can leak and evaporates on hot metal before it ever has a chance to hit the ground and leave a puddle. Ask the man who knows.

 

I also had a leak that I could not see, but only smell; until I was enlightened by a post similar to the one above.

 

yep, that's were mine was leaking when I bought it.

 

still blows my mind that those hoses are there. No other way to route that so you don't have to take off so much to replace them.

 

The good news was once I replaced the Valley Hoses, Octopus Hose, Thermostat Tower, Water Pump, Overflow tank and various other hoses, she stopped leaking completely.

However, I still get a twitch in my left eye when I smell coolant.

 

You probably have lost the magnet out of the float in the overflow tank. I lost mine and the sensor was always activated since the magnet was laying on the bottom of the tank. I just plugged a bad sensor in the connector so the light would stay off. That gets rid of the low coolant warning. Instead I frequently check the fluid level in the evenings.

That float is a very bad design. lots of magnets have fallen out. Someday I will get a cheap overflow tank and cut it open and modify the float and magnet. Then glue it back together with JB weld. I think any new tank could also fail.