I see green stuff on top of radiator. What is going on?
 

Everytime after I drive I notice a little bit of coolant around the top of my radiator. What does it mean? Why is it leaking on top???

Your radiator cap is probably leaking. Or it could be the nipple on the neck for the overflow hose.

Is it around the coolant level sensor on top of the radiator?

where's the coolant level sensor?

Didn't rxseven just say 'on top of the radiator' - it ain't that big, my friend, just look for something ON TOP OF THE RADIATOR with a single wire coming out of it and going to the left as you look from the front of the car - that's the coolant PRESSURE sensor, not a level sensor! If your pressure is low due to a lack of coolant, bad pump or whatever you will have a dash buzzer and warning light.

how is your temp when you are running NORMAL, like within the speed limits, has it ever ran hot on you . did the coolent BUZZER sound ?have you added coolent to it recently, if so did you bleed the system ,if not that could cause some to escape from the cap, thats the one on the rad. check the cap see if the seal is worn-old ,ect. is any also leaking from the over-flow tank. while you are there you might want to check your thermostat to see if it is working or just replace it . while you have the cap off check to see if the coolent is circulating, DON'T burn your self taking the cap off. let it cool down first. it will have to run for a few min to let the thermo open up so you can see the coolent moving around .hope this helps PEACE. ex.. ps,if the coolent isn't moving after it has warmed up either the thermo isn't opening up or the pump isn't working. check all around for leaks.

If you still have the stock radiatior it probably has a crack in the top. Typcial location is on the RH side where the numbers are stamped in it. Look for a hair line crack. If it is cracked replace the radiator as the crack can open up suddenly and loose all the coolant. there are some older posts about this. Replaced my radiator a few months ago due a crack in the top.

No, it's a level sensor. If it was a pressure sensor, it would go off everytime you start the car.

The level sensor leaked on my 87. I was suprised it was under $18 to replace it..

Yo Thaniel that's exactly where the coolant is leaking from...the numbers on top of the radiator.

Can I just seal it with some gasket sealer, or do I have to replace the whole thing?

How much does it cost to replace the radiator?

Thanks

Once those tanks start to leak in one place, others are soon to follow. There's a couple places that'll get you a new radiator for $160-175 shipped.

http://radiators.com/en/index.cfm

http://1-800-radiator.com/index.cfm

To MarkS - the thing on top of the rad is a PRESSURE SENSOR - use your God given brains for a minute and think about how you are going to measure the fluid level in a rad that is designed to, and has fluid constantly passing through it and is only at rest when the car is shut off? You might as well try to measure the fluid level inside a pump! Let me put it this way - I had a situation with my car where the damn thing went off on a regular basis and kept on going off - that buzzer may be responsible for some road rage homicides - the problem was that the water pump was failing and not adequately pressurising the the system - I always had a full load of coolant, but was not getting operating pressure due to the bad pump. Also didn't have any overheat problem. At one point I grounded the sensor to stop the buzzer going off and after replaceing the water pump I haven't had a problem.
To reiterate - the thing is a PRESSURE SENSOR - not a FLUID LEVEL SENSOR which if you think twice makes no sense at all!

You sure have a hard-on for burning bridges today...

Its a level sensor. The pump is there to circulate the fluid not pressurize it - heating it is what pressurizes the system. Squeeze your upper rad hose just after starting the car, no pressure eh? and no buzzer either. The system is also closed loop so if you've properly bled it for air, there is none in it to affect the level sensing due to moving fluid. When you changed your pump, you changed the fluid as well and most likely bled the system as well - this is probably what solved your buzzer problem.

Henrik
87TII

https://www.rx7club.com/forum/showth...threadid=17496

That thread has some useful info.

https://www.rx7club.com/forum/showth...light=radiator

More there as well.

The crack can rupture so I wouldn't wait to long to fix. There are different configurations on the radiators so pay attention to that. (some have the cap on the top in the middle some don't have a cap and 89+ I think have a spout with a cap).

By the way on the level sensor debate: You can create pressure with steam but it won't cool anything. Take the cap of the radiator (when cold) and fill it up start the car and the buzzer won't go off. It is a level sensor not a pressure sensor.

Ianbell:
You are wrong. It is a level sensor.
If you run the engine with the rad cap (no pressure), the buzzer does not go off.
If you run the engine when you first start it, when the thermostat is closed and the pump is pressurizing against it and not pressurizing the system, the buzzer does not go off.
Those running Evans coolant with zero pressure systems will surely agree.
Sean Cathcart

Tell me, know that you've told us all off and that we are not using our brains, how does that foot taste? Hope you didn't step in something...