Overheating

[Southwest]

I am recently having coolant problems. I switched from Evans to 50/50 Dexcool. Then I reviewed that the oil temp needs to be in the green at 190-230. So I put some tape in front of the oil cooler which is in front of the radiator. Oil temp now stays around 200-210 and the CHT is in the green around 200-230. Now the engine overheats in that it spits coolant thru the spider tank overflow tube into the overflow bottle and out the vent hole in the bottle. Before I had no problems with no tape on the radiator, CHT in the green BUT oil temp stayed in the 160 range and never got hotter. Scratching my head on this one other than accepting the lower than recommended oil temp.

[Av8r3400]

Southwest, I moved your post to it's own thread for future reference.


Now, to your problem. With the oil cooler stacked in front of the radiator, covering the oil cooler is also (obviously) covering flow through the coolant radiator. Have you considered an oil thermostat, which bypasses the cooler until it's needed.

Link (http://www.aircraftspruce.com/catalog/eppages/xcomthermostat.php)

[rv9ralph]

Also, after changing coolant, you will get some coolant out of the overflow as the system purges any air trapped in it. (it happened on mine after changing coolant).

Ralph

[mr bill]

Until a week ago, CHT was always in the middle of the green. A week ago, the temp went up to 120 C, so I landed and drained the coolant. I removed the thermostat and put it in boiling water. It opened like it should, so I installed it and refilled the coolant. This time the temp went to 130 C. I again drained the coolant and again found a sand colored material that had settled out of the coolant (4th time). This time, I found coolant leaks at the overflow bottle and what appears to be the water pump. The coolant tank on top of the engine was dry on the outside. The engine was manufactured in 2007 and has 70 hours on it. I am using the oversize copper radiator from Kitfox Aircraft. Any ideas?

Bill

[jiott]

A couple of months ago I sprung a leak in my older style copper radiator from Kitfox. A tube was split so that it only leaked under pressure, not when sitting on the ground. I had lost nearly all of my coolant, in flight, and didn't know it because the overflow bottle stayed full. Finally one day in flight temps shot up to 350 F. Now I have the new much sturdier aluminum radiator, and regularly check my coolant level by removing the top spider tank cap. I don't trust just looking at the overflow bottle.

[Southwest]

For over 300 hours this engine has been trouble free. Just recently I took notice that the oil temp should be in the green of 190-230. Mine never got that hot thus the tape on the radiator. Because the coolant was pushed out of the overflow bottle and thus the engine was overheating Lockwood suggests the sensors may not be correct and he led me to the Rotax manual to check them. We’ll see.

[Southwest]

Until a week ago, CHT was always in the middle of the green. A week ago, the temp went up to 120 C, so I landed and drained the coolant. I removed the thermostat and put it in boiling water. It opened like it should, so I installed it and refilled the coolant. This time the temp went to 130 C. I again drained the coolant and again found a sand colored material that had settled out of the coolant (4th time). This time, I found coolant leaks at the overflow bottle and what appears to be the water pump. The coolant tank on top of the engine was dry on the outside. The engine was manufactured in 2007 and has 70 hours on it. I am using the oversize copper radiator from Kitfox Aircraft. Any ideas?

Bill

For the temp to go higher after replacing coolant suggests air in the system. For the sand color sediment I would flush flush flush the system. If you still see the sediment then an element in your cooling system is disintegrating. Water pump?

[Southwest]

After talking with Lockwood tech dept (Dean) and flight testing we both believe when I refilled the cooling system after a radiator leak repair there was air trapped in the system. With an OAT around 75-80 on the ground I installed about 1 inch of tape on the lower half of the oil cooler. Now the oil and CHT temps are both in the green with no purging of coolant out the overflow bottle. After flying the overflow bottle has made about an inch of increased fluid level and when the engine cools the coolant level reduces to the original level. Dean say this is normal with DexCool 50/50. As a side note, I never saw fluid increase/decrease using Evans coolant.