Thread: Super annoying low coolant alarm going off until car warms up (earth issue??)

So you still haven't cleaned the sensor?
Takes all of five minutes.

So first off, just removed radiator plug with sensor to give it a good clean and coolant did not pour out, nor was it right up the top but very close to it, I'll take a photo of that next. Is this meant to pour out if I open this?

Also a little rust on the sensor so gonna clean it off now.

Should I top this up at this point before opening the thermostat plug and topping up there too?

Better!

In theory it should overflow slightly when removing the bung. But the height difference to the thermostat housing is next to nothing so it could take a while.
Have you cleaned out the 3 way ejector between the rad, expansion tank and thermostat housing.
The ejector removes the air and puts it into the expansion tank.
It should be clear in all 3 directions.
With the thermostat closed there should be coolant flow from the thermostat housing to the expansion tank, this flow causes a venturi effect in the ejector and draws fluid/air from the top of the radiator.

To fill the radiator I remove both bungs and fill from the expansion tank.
The coolant should fill the rad first, install bung.
keep adding coolant to the expansion tank untill coolant can be seen at the thermostat housing, massaging the bottom hoses will move the coolant quicker.
You wont get coolant out the top of the thermostat housing, it defies the laws of physics.
Install the bung and remove the 1/4 hose from the thermostat housing, this is my bleed point. Start the engine, Coolant will come out of the 1/4 barb, refit the hose and it should be good.

Originally Posted by jboot51

....
You wont get coolant out the top of the thermostat housing, it defies the laws of physics.
.....

Not if you don't over fill it, it won't.
But if you continue to fill the reservoir beyond overflowing, the thermostat housing will also overflow(at a lesser rate).
As implied tho, the thermostat housing bung is higher than the coolant reservoir cap. So if you fill the reservoir only to the top of the cap threads, the thermostat housing WON'T be full.

This is why the drink bottle trick works well and gets all air out first time every time. You raise the coolant level to well above the thermostat housing level and cap the thermostat bung by hand and you're done.

If it came to a contest between unbolting the coolant reservoir or using an old bottle inverted into the reservoir, in terms of practicality and ease the drink bottle wins every time!

Can I ask, if I open up the thermostat and there is plenty of coolant in there so I even need to bleed the system? Ot just top up the radiator under the sensor?

Originally Posted by Young Angus

So first off, just removed radiator plug with sensor to give it a good clean and coolant did not pour out, nor was it right up the top but very close to it, I'll take a photo of that next. Is this meant to pour out if I open this?

Also a little rust on the sensor so gonna clean it off now.

Should I top this up at this point before opening the thermostat plug and topping up there too?

Did you have the reservoir cap on?
If so, maybe the lack of additional air pressure on the higher water level in the reservoir(ie. a partial vacuum) could have stopped the flow out the radiator?
Dunno! every time I open the rad plug, I also have the reservoir cap off too.. and it flows out.
Other possible reasons is the level in the reservoir. While it's not a lot higher, it's still higher than the top of the rad, and a full reservoir should drain out with the rad cap off.

'good' to see some rust on that sensor doodad .. to be sure! not good that it's rusted! .. good in the sense that hopefully it's the source of your annoying issue.

What I do for the rad: reservoir cap off, rad bung(or in your case, the sensor) half on/off so that it leaks.
Fill reservoir continuously so that you get a flow out of the half fitted rad cap.
In a sense, your trying to expel any air in the rad too. Hopefully the rad sensor cap thing is an easy hand tightening job too and as you pour water/coolant into the reservoir slowly tighten the rad cap too.

With that rust on the sensor, there is a possibility that you may have rusty scale build up in your coolant system too. If so, it could clog up the rad.

**additional useless info **
A few weeks ago my CEM products came in the mail and the first thing I did was to test the coolant flush stuff. Left it in for a day or so to circulate around then did a flush with the garden hose.
Old coolant came out much more brown that I used to see it in the reservoir which was basically clean water(I've been using straight water for the past year or so).
So this CEM stuff has definitely cleaned something out of the cooling system. When I flushed the rad too, in both directions with the hose, brown coloured water came out from the bottom hose port, but clear water coming out of the top!
Obviously some build up in the bottom of the rad. I reckon I had to back flush the rad at least 10-15 mins alternating between forward and back flushing to clear the flow out the bottom.
Engine basically flowed clean, with some residual green coolant in there.

Actually ended up with a bit of an improvement in coolant temps, which was what I'm chasing .. only with thee A/C on.
Without A/C on, coolant temps stick to high 70's - low 80's without fail, no matter the engine load.

With A/C, in mid 30's ambient, coolant would easily pass 100°C on an easy cruise. Add even a slight rise in the road, and 105° would come quickly and then the dash gauge would climb towards the red, never actually go into the red .. just an indication that it's warming up.
I'd have to both back off almost totally, and turn A/C off and it'd settle back down to about mid to high 90's for a long while after that.. it was hard to moderate the use of the A/C as it's get hot so quickly with it on .. etc.

Other week I went for a bit of a drive .. lots of 40°C ambients between Cobar/Wilcannia/Broken Hill/and Menindee.
I got many instances of 700°C EGT temps which had me backing right off and dropping into 3rd(auto) to keep them in check, but coolant temp never passed 100°C and only hit that 100°C temp for a split sec. Mainly sat at about 95-97°C according to the data log.

I suspect that the bottom of the rad was partially blocked!

Did the chap in Monbulk give the coolant a refresh/flush/etc? was that part of the service?
Did he refill with coolant? ie. do you have coolant in the system.
I'd suggest(with the rust on that sensor) to give the coolant a flush while you're there doing all this other stuff.

ps. you can run straight water too .. don't really need coolant, they say it supposed to help with boiling point level, but the trick is to not allow it to get to boiling point!
Like I said, I've been running straight water for over a year now.
Will eventually top with coolant(got a large 20lt drum of it now) .. just been lazy and more accurately I'm still in between flushing phases AND trying to get off the posterior to do my silicon hoses change.