Okay, I think my coolant sensor is flaky. Sometimes it goes off barely a mile from home, other times I can drive for an hour in stop and go traffic without a peep. There seems to be no rhyme or reason to when it goes off.

Here's what I know:

* No engine drips
* Full radiator
* Overflow just below full line
* Radiator checked and flushed within last 18 months
* All new hoses within last 18 months
* No dampness or crystals around hose clamps
* Radiator cap seems nice and tight
* Coolant light never comes on
* Engine doesn't get even to 1/4, let alone dangerous heat levels
* No consistent pattern of time, distance, road incline, etc, to when buzzer goes off

So is there something else in the coolant system I should be looking for, or is a faulty sensor the most likely culprit? I know no one here can give me the definitive answer, I just want to know if there's something else really big, important and potentially engine-killing I should be checking.

It just strikes me as odd that the buzzer can go off a mile from home, but then not again for the rest of the drive to work, not at all while running an hour-long afternoon errand or while going to the gym the next morning, but then 6 blocks away from the gym, BEEEEEEEEEEP!!!

Then nothing more.

Just a grumpy old car, perhaps?

 

Does the coolant light come on during the startup self test - is the bulb ok?

The buzzer can also sound for low oil level - it that bulb OK?

A loose connector on either of the above is a possibility.

It will also sound for RPM red line, but you already know that..

 

I know before I converted to the S5 radiator setup, mine was kind of picky as well. You had to fill the radiator to the very top until it gushed out of the bleed screw otherwise it would beep intermitantly. Also make sure that there isnt a hairline crack in the thermostat neck. If you squeeze the upper hose and hear squealing, that could be the problem.

 

Three places that small coolant leaks like to hide:
The heater hose nipple under the oil filter.
The coolant circuit from the TB back to under the UIM.
The back water pump housing to front cover seal.

 

I had this after I installed my rebuilt engine. After you drain the coolant, there a lot of air in different pockets in the system. It took me 3 months to work all of the air bubbles. The radiator is the low point in the system. You should be topping off the system at the filler neck on the engine. top it off cold, then drive it for a while, let it sit over night then top it off again. Do this a few times and it will work all the air bubbles out of the system. Once filled don't open the radiator cap, or you will introduce air into the system again. If this doesn't work for you, the you probably have a coolant leak or sensor problem.

Good luck, hope it works.

Mike

 

or you could check the connection on the coolant level sensor on top of the radiator, since people like to pull that out as a bleed screw, the wire can get twisted and broke.

 

If you are 100% sure your not having any coolant issues, i'd suggest doing a little ghetto rig I did on mine. Splice a new wire off the sensor wire where it isnt very visable (under the intake) and ground it to the frame. Beeping gone, sanity back, its only ghetto if its visable.

 

^Bad advice. Keep working on it until you fix it.

Are you sure you bled the system correctly? Have you tried replacing the sensor yet? They rarely go bad but it's a cheap part.

 

it aint called a ghetto rig for nothin!
The right way thread... He's right, do it the right way.

 

Did you open the bleed screw when filling up the radiator? I f you didn't the buzzer may go off when the thermostat opens up.

 

I'll just wait for him to reply at least once before flooding the thread... LOL

 

In case you have an S5, note that they do not have coolant bleeder screws like the S4's have.

 

Too many places coolant can leak...
Rad cap...
Bazillion hoses (water pump to BAC, BAC to TB, TB to rear iron, lower rad to heater side pipe in engine bay, heater side pipe in engine bay to heater core in fire wall, heater core from firewall to rear iron under oil filter, upper rad hose, lower rad hose)
Heater core itself under dash...
Water pump, water pump housing, thermostat housing...
Radiator core itself...
Water coolant jacket o-rings failed internally.

You sure you checked ALL of it?


-Ted