rotax 532 overheat

gdoulou

Junior Member
Joined
Sep 5, 2005
Messages
13
Location
Larnaca, Cyprus
I have an aircommand 532 elite which i have had for about a year and it flew for the first time last weekend

the engine supposedly had only 10 hours on it but after it landed coolent was sperting out of the radiator cap

can anyone sugest what i should check for thankx


gdoulou (cyprus)
 
Does your 532 have a thermastat? If it does then
Do a hot water test of the thermastat. Could be defective.


Thom
 
George, we would need more information to provide detailed help.

If the system has a thermostat, remove it. Rotax recommends that no thermostat be used in their water-cooled engines.

Is the engine mounted with the sparkplugs down? If so, there may be pockets of air in the engine's water passages. This can happen with the plugs-up mounting as well, although it is less common. Some people have installed vent plugs in certain places on the crankcase, to help you bleed the air out when you fill the system.

What size is the radiator? Some of the early Air Commands came with a very small radiator that was not adequate.
 
It sounds like it may have the oil cooler type radiator which was not very efficient.

Doug, I always ran Rotax thermostats in my 2 strokers.

Aussie Paul. :)
 
thankx for your replies
I striped the engine last night and found that there was no thermostat in it anyway , the engine is inverted but there is no coolent overflow bottle. should I fit one?

george (Cyprus)
 
Hello George.

Must have a overflow or expansion recovery bottle of some kind, a auto coolant bottle should do.

Hello Mr Doug.

I m always uncertain about the thermostate opening or closeing, it is news to me that Rotex recommands NO thermostates.

Out here it might be Ok not to have thermostste in summers but winters are cold and with an over size radiator, I feel that my 582 might run too cool and endanger cold ceasures.

Thank You.
Rehan
 
Hi George, Do you have a water temp gauge? If so what was it reading at various times? Do you have a picture of your setup showing where the radiator is relative to the air flow?

I had overheating problems on a new 582 which have been solved through a changed radiator position.
 
Having NO thermostat can easily cause an overheat, the therostat acts as a restrictor in the system. In some cases, removing the thermostat will allow the coolant to flow through the radiator too quickly and not get a chance to get cooled down.
 
My understanding of Rotax's no-thermostat recommendation is that the opening of the thermostat in cool weather can cause a cold seizure, by chilling the engine with unheated water from the radiator.

Of course, most of the people participating in this discussion don't HAVE cool weather.

Here in northern Vermont, where we have already had snow, it is sometimes impossible to bring an engine without a thermostat up to operating temperature. It is necessary in such weather to block off at least a part of the radiator (and the oil cooler, on a 4-stroke).

George, you may wish to check the adequacy of your radiator. As Paul said, early Air Commands had one that simply was too small.

Air bubbles sometimes get trapped in the cooling passages of inverted engines. I believe some of the Rotax literature shows locations where you can add vent plugs to help you remove the air.
 
thanx againe for your replies guys
would it be possable for the engine to over heat if the one cylinder fired at 18 degrees BTDC and the other cylinder fired at 10 degrees BTDC,
because after checking the timing thats what i found the timing to be set at.
I have now brought both cylinder to 18 degrees BTDC as it says in the book

thanxs again

george(cyprus)
 
George
Its me who test flew your gyro for a week ago just before I left
from Cyprus to St Petersburg.
Dont have illutions, you bought that gyro second hand from ebay
... (10 hours on body and engine. ha ha) If you still believe that, OK, I give up.You know how many modifications Ive done before flying it and how many
still needed to be done. This gyro is thirteen-fifteen years old.
What I want to say BUYERS BE AWARE FROM SECOND HAND GYROS unless you know the history of it.
Wait tills I come back and we will fix even that problem.
Giorgos
 
I have now fitted an overflow bottle and a thermostat and had the radiator flushed properly, i ran the engine at 4000 rpm for about 10 minuets and the temp didn't rise above 70 degrees c ,so i think it has been cured but I will have to wait for george (scandtours) to return from his travals to be 100% sure it ok ,oh I also swopped the rad cap from 7lb pressure to .9bar the guy at the store told me it was a slightly higher pressure.

thanks for all your help guys

george(cyprus)
 
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