Coolant leak

[jiott]

What keeps it from overheating is a properly sized radiator and oil cooler. A thermostat only helps from overcooling. Most of us don't have an actual coolant temp readout, but if either the CHT or the oil temp gets close to the redline, you have a problem and need to figure out the cause. Most likely an airflow restriction thru the radiator/cooler, a partially clogged radiator/cooler, a kinked oil line, a collapsed radiator hose, low coolant/oil level. Its pretty rare for a coolant pump to completely fail; usually the seals go bad first and you will notice leakage and loss of coolant.

[fastfred]

Thanks Jim
I am trying to duplicate the climb and test it. I guess it was a combo of High heat , high RPM, high weight and most likely high density air.
I lost a quart of coolant but I can't see where it came from is my problem. I think the leaked stop once I leveled off into cool air? Otherwise I was diverting
I am going replace the hoses and clamps first. We are guessing they are original and I will clean out the radiator . How about that synthetic coolant rotax recommends? The radiator doesn't look that dirty but this is a new plane to me so who knows if it was ever cleaned out or how old the hoses are. I could smell a hot hose was the only thing that told me there was a problem.

[jiott]

The waterless coolant Kitfox used to recommend is now definitely NOT recommended by them. If that is what is in your system, it needs to be properly drained and cleaned out, and refilled with Dexcool 50/50 anti-freeze. You will find your temps will drop 10-20F.

[fastfred]

That 50/50 is what I put in last fall . One of our locals has the rotax repairman class and said they recommend the waterless . Not sure how long ago he took it.

[jiott]

He must have taken the class a year or more ago; Rotax has flipped on the Evans and now recommend against it.

[fastfred]

I am sure he took it a long while ago. Glad I spoke to you before I ordered it.
While I got you . How often do you change the plug wires? My left side recently started to drop 200 rpm in run up. Plugs have about 30 hours on them.

[jiott]

I have 600 hours on my original plug wires and don't plan to change them soon. Before I change plug wires I would try unscrewing the boots and clipping of about 1/4" of wire and reinstalling the boot. It often solves ignition problems.

You really should be continually monitoring the Rotax-Owner website and read the forum posts on a regular basis. Nearly all the questions you have asked have been discussed many times on the forum, including my suggestion of clipping the plug wires. Any Rotax owner doing his own maintenance should be reading that forum. That website also announces each new service bulletin as it comes out, like the one recommending against the Evans coolant. A Rotax repairman who doesn't keep up on service bulletins would be highly suspect in my opinion.