Coolant leakage

[Deanrobert]

We do get a low coolant light at start-up; after warming up it goes out- no overheating .. going to check further on the head gasket area

[Wilfried]

A couple of years ago I had a coolant leakage on both engines at the same time. We detected the leakage after landing in Kangerlussuaq after a 4h hour leg over Greenland No joy! It could have been our last flight. We tightened the hose clamps and thereby stopped the leakage. The hoses had been replaced according to the regular maintenance intervalls a few flight hours before by our shop...

[UTMark]

We're getting similar symptoms on our RE... however this normally occurs for us after a flight where we've been running at a higher power setting like 90% rather than 75%...

[photoSteveZ]

My case was loss thru the relief valve.
Low coolant announce was observed on the next flight.
Loss appears to be in-flight but I did not see the fluid until later when it had drained down to lowest point and dripped out. No visible indication of loss while flying, no high temp condition, initial discovery was next morning after long flights.

My experience matches this. I've had the coolant system serviced and replaced relief valves, a couple of times, without solving the problem.

[janders]

I see the same thing. I've had a `R COOL LVL` which seems to go away just prior to departure since I first purchased the plane. Usually takes about 15 minutes of time for the Coolant Temp to come into the green then it goes away. I have never had any fluid leaking observed.

My plane is going to SouthTecAviation for its annual soon and it's one of my questions as to what's going on.

[Karl]

I see the same thing. I've had a `R COOL LVL` which seems to go away just prior to departure since I first purchased the plane. Usually takes about 15 minutes of time for the Coolant Temp to come into the green then it goes away. I have never had any fluid leaking observed.

My plane is going to SouthTecAviation for its annual soon and it's one of my questions as to what's going on.

If the light comes on it needs topping up.
In this case it seems to be right at switching level between adequate and low. As it heats up the coolant expands and raises the level enough to activate the switch.

Low coolant can cause cylinder head issues and as the low coolant warning is recorded in the FADEC then Diamond will be able to deny any warranty should they wish to.

My advice is to get it topped up ASAP.

[vnehess]

I Agree, if the COOL LVL on it needs topping up or the sensor has failed.

To complicate matters, in the midst of diagnosing my root cause, the mechanic did correctly diagnose and replace the coolant level sensor due to observing COOL LVL after a refill.

[CFIDave]

You may run into an issue if you simply try to top off the coolant after receiving a COOL LVL annunciation:

After cutting the safety wire and removing the "radiator cap" on top of the expansion tank (the next day after the engine is completely cold), you may find that the system will still retain some pressurization, coolant will overflow out the top of the cap opening, and you'll see that there's no way to add more coolant.

To add more coolant and make the COOL LVL message go away, you need to remove some of the air trapped in the system to drop the coolant level in the expansion tank. There are two "bleed screws" on coolant pipes that can be removed, but what works even better after removing the cap is to pry open the coolant high-pressure relief valve (you don't need to cut its safety wire to do so) on the side of the tank. Once you open the valve even a tiny amount (by pulling it straight out with pliers, an open-end wrench, or a flat-blade screwdriver), you'll immediately see the coolant level drop so you can add more fluid.

Put the cap back on, and run the engine on the ground, getting it hot enough to open the thermostat to remove any more air potentially trapped in the system. Run the engine until the coolant temp on the G1000 shows at least 80degC; you'll see the temperature drop a few degrees when the thermostat opens. Let the engine cool overnight, and again check the coolant level in the overflow tank to see if you need to add more coolant. Repeat if necessary, and then safety wire the cap.

[CFIDave]

Even though I posted this in another thread, here's an easy way to obtain more coolant for Austro engines if you live in the US and have a NAPA Auto Parts store nearby. This stuff is pre-mixed so you don't have to dilute with distilled water; just pour it in.

https://www.napaonline.com/en/p/ZRX859537

[Davestation]

Low coolant can cause cylinder head issues and as the low coolant warning is recorded in the FADEC then Diamond will be able to deny any warranty should they wish to.

Shenanigans