1990 stock convertible coolant issues
 

So, I finally got back around to working on my car. I just haven't had any time lately and so I finally think I'm just going to sell it and get it to someone who can take care of it properly and get it back to perfect running order (hopefully). However, there are some issues before I sell it that I need to correct. One happens to be an issue with my coolant level sensor. It seems to go off selectively. It's not all of the time, but during a 15 minute drive it may come on and go off 2 times. If I give it a little gas, the light goes out. I've purchased a new sensor and no change. I've also replaced the coolant fill neck cap as well with an OEM part from Atkins Rotary. I've also done a coolant flush and replaced the non-oem thermostat with an OEM one from Atkins as well. I thought perhaps I was having the dreaded coolant seal issue that seems to be prevalent on these rotaries from what I can tell when it's not taken care of properly. I decided to do the coolant bubble test, and failed really badly. When I take the cap off the coolant just seems to flow out pretty rapidly. I let it flow out to the point where it finally settled down and then it seemed like it needed more added. I slowly added more and more flowed out again until it settled again. During this time I did have the heat and fan on full. The fact that the coolant was just pushing out really worries me about the coolant seal, but I would assume that if the seal were that badly broken I wouldn't even be able to start or run the car. Is that assumption correct? I'm really hoping it's not a bad seal. I still think I could get a decent amount for the car given that the body is in great shape and so is the rest of the car, but with a bad motor it definitely puts a damper on the situation. Any help is greatly appreciated.

Apoc

engine is in need of a rebuild.

Hold on, maybe not

The way i read what you posted, you opened the radiator cap with the engine running, how long was it running??? If any more than 5-10 minutes i can see the coolant gushing out because the system was under pressure

What you need to do, is top of the cooling system, leave the cap off at the highest point (if you have the cap on the thermostat housing, this is best). Start the car and let it idle for about 20 minutes and watch for bubbles

But, in another way i agree with styx that the motor needs rebuild because of your sensor going off randomly. But rule everything else out before deeming the motor done

I did have the car running for about 5 minutes before I pulled the cap. At one point the gushing stopped, but only when it seemed like it ran low on fluid to push out. After I filled it up some more the fluid slowly would rise and then push out some more, but it seemed to eventually sit. Maybe I just need to give it a chance to equalize properly? Anyway, thanks for the response, I'll give it a shot.

To me it sounds like you have a bubble in the cooling system

Try this, jack the front end up, top the coolant off and start it and let it idle with the thermostat cap off (if you have this style, if not, leave the rad cap off) and let it idle with the heat blowing on high for a good 20 mins. Keep the coolant toped off the best you can, and keep your eye on your gauges (temp especially)

If it keeps gushing coolant after 20 mins of idleing, than yes, coolant seal or iron is cracked, if it doesn't, shut it off, button everything back up and take it for a drive and see what it does then