On my 1985 GSL-SE the cool light comes on every once and a waile and my coolant Bottle is full and the rad is full. And when it comes on I give it a little gas and let off the light goes off and stays off for awhile. Is there a level sensor in the coolant bottle that is causing this or the one on top the rad

 

you have 2 choices, there either IS air in the cooling system, or the wire for the sensor is bad and grounding somewhere.

i suggest looking at the coolant level sensor wire. the light turns on after it sees ground.

plan b assumes the sensor is right and you have air in the radiator, a small pinhole leak can cause the symptom you describe. bad water pump too.

 

The sensor is on top the rad, BTW, not on the bottle.

 

Sounds like the sensor on the top of the rad to me. The wire on them usually breaks off, and causes this. Sounds like yours is about to break, causing the light to go on and off.

 

Check the sensor wire first - easy to do. On most 7's the insulation on that wire is old and very brittle. It can crack and expose the wire inside.. It has a long path along a grounded surface........

 

its annoying and i know i dont have any leaks. but mine kept coming on.....

so i cut the wire and grounded it to the shroud thing above the radiator. no more annoying light and buzzer for this guy

 

This is not a course of action that I recommend. It's like the boy that cried Wolf. You want that sensor fully functional.

 

^ Exactly - every had a rotary overheat? If so, you'd make sure the sensor worked. They are cheap

 

the sensor works... but ive had the car for 2 years and every time ive checked the coolant im on the mark. and never has it ever came close to getting hot.

but on that note i check all of my fluids constantly so for someone who doesnt do this then i dont recommend grounding it

 

One of the possible causes of this can be a sensor with a hairline crack in it, or a tiny leak in the rubber gasket - - they are fragile, and made of plastic so they get brittle with age

Because they are cut so a largeish wrench will fit on it, people tend to over torque them. Sometimes they snap off, sometimes they just crack a bit... and being at the high point of the rad, a small crack can cause them to suck air as the rad cools down between runs.

I had a sensor go this way, once; the "head" portion had cracked above the threads, so it was not pressing on the gasket as tightly as it should. It never leaked water visibly, but after shutting the car down, it would end up "inhaling" air (preventing the cap/reservoir from working right, too, by spoiling the vacuum) as the coolant cools and contracts. After one or two runs, light would come on at restart, but would go out as the engine heated up and it farted the air back out.

Drove me nuts for a week, sorting it out.

 

ive had this happen too. and on my old t2, i had a copper washer on the turbo water line that did this too. no external leak, but it did suck enough air to turn the add coolant light on

 

While we're on the subject my damn coolant gauge doesn't read. I replaced the water temp sensor in the block and hooked it up all good and I think it's the ******* stock gauge. Same with my Oil Pressure. What kind of single aftermarket gauges do any of you guys recommend? Also the wiring is a bit shitty to the sensor, but I tested it and it's ok..

 

I found my problem the coolant level sensor on top the rad. The wire is bare and barley hanging on. Were is a good place to get a new sensor at

 

https://www.rx7club.com/showthread.p...t+level+sensor

They probably have gone up in price since the above link.