1995 960 sedan 86,000 miles

Background: Coolant reservoir light started coming on several years ago. Open the hood, open cap, top off a little bit. Coolant would be spit out as soon as we drove it. Realized coolant level sensor must be a bit too sensitive. I just check on it once a week, and figure if the temp ever goes up, I'll notice anyway. Never does. Level stays right in the middle of the reservoir. Earlier this year, the light came on and stays on, even though the coolant level is right in the middle.

Questions:
1) Does this seem as if it is a problem with the sensor and it should be replaced? Anything else I should look at?
2) Should I replace the whole reservoir while I'm at it?
3) Cap was replaced by mechanic a few years ago, but was an aftermarket. I know some people want Volvo caps only. Is it worth doing, or just wait for it to fail?

 

replacing the reservoir (and cap) is not a bad idea considering its 25 years old. Sounds like the level sensor is toast as well. See if Tasca Parts sells Genuine Volvo parts at a fair price vs after market and make your call once you see the price.

 

So I was reading that the problem might be the float in there not floating. Is this a possibility? Can someone describe to me how to best get the float to float if that's even possible? Or describe the mechanism how the float and sensor work together? Is the float part of the expansion tank and the sensor just reads its position? If so, sounds like replacing the reservoir tank might be the first step if the float is the problem. Maybe the sensor is fine.

 

I don't believe there is a true float, it's just a sensor and it's most likely your problem.

 

OK, thanks gain, Lev.

 

A follow-up. Replaced sensor. This did not solve the problem. There does seem to be a float rattling around in there. I'm guessing the way this works is that it floats around the cylinder of the sensor and the sensor reads the float position. Not entirely sure, since I haven't cut it open to see inside the tank. I could just tell that as I was working on it empty, it was rattling around inside of it. Next step is to replace the tank, I guess.

 

OK, replacing the tank fixed the dash light. The float was clearly moving, but obviously not the way it should. New one is good.

Also has added benefit that new tank is more transparent, making it easier to see fluid in tank.

 

It's nice to hear feedback/results on issues people are having and when a repair worked. Thanks for posting.

 

Just to summarize: the sensor clearly needed to be replaced. The wires were all corroded and the insulation was falling off. The socket had basically fused to the plug, and it was challenging to get apart. I mangled the socket getting it apart. It is clear to me that coolant/water comes out of the tank in an overflow situation, and that gets on the wiring. The tank itself also had some sort of problem--The float (or whatever) that sends the signal to the sensor was present and rattling around in there, but was not sending the signal correctly to the sensor.

The symptoms started off with the light coming on when the tank was just below half full. I would top it off, and it would spit it out all over the ground as soon as it had driven even a small amount at full temperature. Eventually, the light was on all the time. If you have these symptoms, I would start with the tank, and replace the sensor if you notice the problem with corrosion and wiring that I did.