ok, well some of you may have read my other threads about the cooling system problems i was having. well everything has been fine for the past few weeks until the other day.

the other morning i was on my way to work, everything was fine, all of a sudden the add coolant light and buzzer came on. pulled over, popped the cap and the coolant was a little low but not much. but i did notice my coolant res. was empty, so i topped them both off and went back to driving. no more then 1 mile the buzzer and light came back on. so i took the car home and parked it for a few days. coolant was still fine after a few days.


fast forward to today, drove the car to work everything was fine. went to go to a dr. appointment and about 5 minutes into the drive the light and buzzer came on. got it there and let it sit while i was inside. came back out, popped the cap off and the coolant was full and the res. was at half like normal. so i put the cap back and went back to work. of course the buzzer went on and off the whole ride which was about 10 minutes.



1. ive checked to make sure the sensor wire isnt grounding and didnt find anything.
2. no over heating or steaming any where
3. no external leaks i can find
4. no smoking at start up or while driving.
5. oe cap and thermostat.


so, am i missing anything or any other ideas i should try? i love this car but if im going to have to keep sealing with this same issue and keep throwing money at it i might as well sell it. which i really dont want to.

so any help would be great.


forgot, its a 1990 s5 vert 5 speed with about 160k miles on it.

thanks

 

sounds like the coolant sensor is bad i just eliminated mine and got a aftermaket gadge maybe u should think about doing the same thing. honestly the only reason that is there is for retards that dont watch gadges while they drive hense (dummy cluster)

 

Well if you have some time and 2 dollars go to the junk yard and grab a couple of coolant level sensors, (they are pocket items) throw one in to see if it remedies the problem.

 

Air in the system will do this. It's pretty unlikely that a coolant level sensor would be "bad." It's just a metal rod with a wire connected to it. If the wire is on there, it's going to either work all the time, or none of time.

 

yeah, i was thinking about just getting rid of it. just havent had the time or funds. as for going to the junkyard, they dont have any rx-7's so im sol there. and as for air i just cant figure out where it could be coming from no leaks that we can find and we dont think it making it into the combustion chambers.

 

Are you bleeding the system properly when you add coolant? The screw on the radiator should be slightly opened. Switch the ignition 'ON' and run the heater. This will open the heater valves and allow water/air to flow out of that area. You can even run the engine if it's cold.

 

One external leak that is hard to find/notice is the coolant hose that runs behind the throttle body by the firewall.

 

Use a VOM---unplug the sensor at the rad---set the meter to ohms, put one lead into your radiator--touching the water, the other to the wire leading to the sensor, you should see some connection on the meter. If thats good, follow the wire back and see if its cut, damaged or broken along its path back to the ecm, or get the pin out for the ecm and unplug the block that contains the sensor wire--then check continuity there--you should see "0" ohms or a 100% no resistence conection. then leaving the meter connected to the 2 ends, go through and wiggle the wire harness, it helps to have someone else watching the meter when you're doing this.
Sometimes electrical can be the most frustrating and time consuming part of taking care of these things.

 

This happens on my s5 NA after a coolant change. I park the car on a slope so that the side that the filler neck is on, is higher than the other side of the car. I leave it for a few hours, then pull the cap and top it off. It's eliminated the 'random' buzzer every time. The air bubble will come out on its own if you help it a little.

 

yeah, i have been using a leslie funnel. last time i bleed it was about 3 weeks ago. dont have the oe radiator in it since it decided to blow up the night i got the car.

buzzer came on twice yesterday on the drive home for about 10-15 seconds each time. hasnt come on since. gonna mess with it some this weekend. only thing im worried about is pulling the sensor out. last time i did i noticed the plastic thread part was cracked all the way down. wrapped it in some plumbers tape. doest leak any. need to get a new one. but ive been ordering so much crap from the dealer i need to let my bank account build back up.

 

If you don't have an OEM radiator, or one with a bleed screw / filler neck, that'll make your job harder. The top of the radiator is fairly high up, and it'll be easy for air to get trapped. Run then engine with the cap open (when cold!) to see if it'll come out. Of course, when cold the thermostat is closed, so even that may not do it. I've had air bubbles in the past, and they would set off the buzzer just like you're experiencing.

 

yeah, there is no bleeder on this radiator. sucks. wish i would noticed it when i got it. would have gotten it from another company. im on the look out for one of the thermostat housings with the bleeder and cap on it to help with bleeding it in the future

 

Those are S4 thermostat covers, which can't be swapped in place of an S5 version. The bolt pattern isn't the same, so you would have to use an entire S4 water pump housing.

 

what temp do you see (while its buzzing??)??

 

less then half on the stock gauge. which i know arent the most accurate. but it has not gotten any higher then that

 

if i were you i would watch your gage and unplug the coolant level sensor, take a foot and a half of wire, hook up the female conection to your wire, then run that wire to you neg battery terminal. if you have an s5 i would invest in a temp gage, but if you have an s4 it will be fine. the s5 gage only has three settings. cold, running temp, and time for a rebuild.

 

You need to replace this ASAP.
It's conceivable that all your problems are due to a wonky sensor.

The S4 gauge may be more linear than the S5 but it's hardly "fine".
When chasing down cooling system problems you need to know actual temps, not just "1/4 on the gauge".