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Another Gyroplane Problem: Overheat

J

Jon Carleton

Newbie
Joined
Aug 7, 2018
Messages
22
Age
69
Location
Georgia
Country
USA
Snowmobile
2009 FX-Nytro on Gyroplane
Me again...that Yamaha-powered gyroplane guy. I'm having a bit of an overheating problem. My implementation is setup the same as several other gyroplanes we have that operate without issue, so I am confident of the plumbing. In the recent past, I have replaced the water pump (cracked impeller) and the thermostat, though it may not have needed replacing.

The symptoms is a thermal warning, verified by noting the engine temperature (fairly hot) and the radiator temperature (luke warm). This is not immediate, and does not occur until after about 15 minutes of running.

Thinking it is a circulation issue, I removed the thermostat (I realize I must put it back for normal operations) with no change in the problem. I am reasonably sure I don't have a bubble in the system...but not 100% sure.

So...first question: What is that round contraption beneath the throttle bodies that has water lines running to and from it? What does it do? Could it be part of my problem?

The second question, before I tear apart the engine again to check out the water pump (no small task in an aircraft implementation, as it requires pulling the prop, reduction gearbox, clutch and pre-rotation devices): Is there anything else I may have missed checking?
 

have you pressure tested it as it might have a bad head gasket.
 
I think that round "contraption" you are talking about would be the oil cooler. Are you getting circulation at rad cap? Feel the hoses. Once warm they should all be same temp and firm.
 
Circulation is a definite problem. Oil cooler makes sense, and it is much hotter than it should be. Does it have moving parts, or should I focus on checking the water pump? Just FYI, this water pump has less than 10 hours on it.
 
If the head gasket is bad, and I pressurize the water system, I would expect water in the cylinders, correct?
 
Yes, it is pushing coolant into the overflow, then it sucks it back. Sometimes it overfills the overflow.

Neither the oil or coolant appear to be contaminated.

One odd thing....there remains pressure in the radiator even if the machine sits overnight.
 
Last edited:
head gasket is bad from the sounds of it from what it is doing with the overflow bottle.
 
UPDATE:
I pressure-checked the cooling system and it doesn't leak. I am thinking that probably rules out a head gasket problem. Pulled the water pump. It is like new and the impeller is fine. What I have noticed is that the radiators aren't that hot, but the oil cooler and oil tank are blistering hot. Do oil coolers go bad? I plan to pull it and examine it today, but I don't really know what I am looking for. That style oil cooler is foreign to me.
 
Many head gaskets will only leak once the motor heats up from expansion. I still say head gasket and I base that on my years of dealing with customers that have had same problems you describe. The gaskets leak externally from combustion chamber into the coolant jacket once they heat up. The combustion pressure exerted into the coolant jacket disrupts the coolant flow and prevents proper circulation. The extra pressure then forces coolant into overflow and often overfills it. Just had a customer last season that could actually ride his nytro easy and it would be fine, but if he ran it hard it would over heat and start pushing coolant. New head gasket....problem solved.
 
If you can post some pictures of your set up that would be great. Last year I had a customer putting apex in a plane and he was having trouble with it getting hot. After viewing photos, I was able to tell right away that his radiator would air lock based on his layout. If not laid out properly the cooling system will not naturally bleed air as you fill. If you fix the head gasket you want to make sure to address the issue for the head gasket failure.....which is usually an overheat situation.
 
It may well be the head gasket. I wish there was a way to be absolutely certain BEFORE replacement, as it is no small task. I have replaced 2 head gaskets in the past on this type gyroplane Yamaha implementation (not this specific machine). Removing the prop, reduction drive, rotor pre-rotation mechanism and half of the motor mounts is required to get access in addition to removal of the typical engine components. That said, I have run out of other suspects, leaving head gasket by default alone.

This machine is built like 25 others that are flying now in the US and many more overseas. It is not a one-off implementation. The cooling routing is identical to other machines that are not having this problem.
 
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