"Cold seizure"

[pudestcon]

Anybody who knows me rolls on the floor laughing if they hear I'm fiddling with anything mechanical; such is my reputation:blush:

 

So with that in mind I ask this question that may seem dumb to some people. The T300 that I flew yesterday had a "cold seizure" engine failure today and was successfully landed just off the end of the strip in a cultivated paddock. The description of a "cold seizure" as related to me is that the suitably warmed engine came in contact with a patch of extremely cold air at about 100 feet or so which caused rapid cooling of the engine parts resulting in an almost instant engine stoppage. Does anyone have some extra information on this phenomenon and/or can offer some opinions or insights? I have already discussed the possibility with my mate poll about the unleaded/oil mixture and whether this could be a contributing factor.

 

Cheers,

 

Pud

 

 

[Guest Maj Millard]

Are we talking Rotax Pud ?....and if so, Fan air cooled or 582 water cooled. Or heaven fobid a Cayuna ?...they had a habit of just snickin up for no particular reason.................Maj...

 

 

[pudestcon]

Thanks David, I'll check it out.

 

I wondered if you would surface on this one Maj;)

 

It's a Rotax 582 blue head with a split (2 separate tanks) radiator.

 

This is the engine here.

 

Pud

 

 

 

[Guest terry]

Thanks for that david, there will be a therostat in my 582 before our firstflight

 

Terry

 

 

[monty]

Hey Pud,

 

Was it a Student? It would of been great experience in training! There is a solution Just fly in the Summer time haha. I hope my 503 doesn't do that to me!!

 

Monty

 

 

[pudestcon]

Hey Pud,Was it a Student? It would of been great experience in training! There is a solution Just fly in the Summer time haha. I hope my 503 doesn't do that to me!!

Monty

G'day Monty,

 

It was the owner of the aircraft doing a test flight after repairing a problem with the radiator mount. He landed in the paddock I always have my eye on if I need to land. The summer time here is, I suspect very similar to Winton - you fly very early morning and sometimes late afternoon/evening, else the booming thermals will getcha:yuk:

 

Pud

 

 

[Guest Maj Millard]

I have done well over 600 hrs with a 582 in all conditions hot and cold, without any problems. Have always considered the thermostat to be a must in any closed radiator based system, either plane or automobile. It is there to maintain a set system pressure, which is necessary to keep the coolant circulation constant, to provide suitable and stable cooling and heating.

 

If this engine was not fitted with one, then who knows what problems may occur ?.

 

As a footnote the Rotax 582 thermostat can be a little expensive, however it can be replaced with a Kawasaki one which is identical in design and operation.(KR250) Thermostats must be fitted correctly as far as flow goes, and the little steam release hole has to be at the top..............................................................................................Maj..

 

 

[pudestcon]

Thanks for the info Maj, I will ensure my 582 has the correct thermostat fitted before the 1st flight.

 

Pud

 

 

[Guest terry]

Hi David ,as I understand it all 582's are supplied from the factory without one.

 

WHY

 

Terry

 

 

[Guest rocketdriver]

I wonder if this is the real cause of the often quoted unreliability of two stroke motors?

 

 

[facthunter]

Thermostats 582.

 

they are not the complete answer. Sometimes they open quickly and a rush of absolutely cool water from the radiator will go through the water jackets and cause the thing that you don't want, to occurr.If a thermostat is fitted, the system should have a bypass like cars do to circulate some of the hot water and mix it with the cool water coming in from the radiator, before it enters the engine. I have never flown a 582 engined aircraft that had a thermostat fitted. Anything I have flown did not have one and the weather down here is a lot colder than where you fellows are. Generally the number and size of the radiators determine how hot the engine runs. You would be better to have a controllable shutter or blind on the radiator (or tape) if you have large variations of ambient temp. to cope with. The piston seizures depicted in the article, would not have happened if the clearance was a bit more. The piston classes are in two grades for a nominated bore size. Getting the clearances too fine creates an unreliable engine.

 

I can not understand why Rotax use a cast iron liner in their 2-strokes and a nikasil one in the 912 series. Virtually ALL 2-strokes today are nikasil (or similar) and can run with much finer clearances and have a lot less chance of piston seizure as the expansion rates of the piston and the cylinder are close to the same. Nev

 

 

[icebob]

Hi,

 

Terry, I can confirm my last two Gray head 582's (older style/model)both came without a thermostat.

 

Bob.

 

 

[Tomo]

Hey Pud:

 

Agree with Nev on the thermostat thing...

 

I have trouble comprehending the fact that it could be a cold seizure issue (doesn't mean it isn't though!) But on take off, full power, and climbing (assuming) the airflow and power setting makes it hard to imagine any amount of cold causing a stoppage, on a water cooled engine - one of the reasons engines are water cooled... so they can handle thermal changes better.

 

A seizing engine sounds like it's slowly getting stalled - loads up, and stops hard. They don't just stop and windmill down. So if the pilot can remember what it did... did it windmill to a stop, or totally seize up?

 

 

[monty]

G'day Monty,It was the owner of the aircraft doing a test flight after repairing a problem with the radiator mount. He landed in the paddock I always have my eye on if I need to land. The summer time here is, I suspect very similar to Winton - you fly very early morning and sometimes late afternoon/evening, else the booming thermals will getcha:yuk:

 

Pud

Yeah Pud,

The same here, Early morning or late afternoon is ideal but I can't always choose. You have to fly when you can, especially when mustering that's why I bought a Drifter. It may be uncomfortable sometimes but I know I am safe. (Well sort of)

 

Monty

 

 

[robinsm]

The 582 used to come without the thermostat. It was listed as an optional extra. Good tip about the Kawasaki thermostat. (rotax one is $120 or thereabouts from Floods! How much for the kawasaki one?)

 

Cheers

 

Maynard

 

 

[horsefeathers]

just a quick question about the explanation for this "cold seizure" phenomenon.... (gee can you see my bias showing yet????)

 

• why didnt my trail bike ever experience such a thing when it hit water crossing creeks etc?
   
   
  
• what about jetskis, that travel thru different water temps all the time?
   
   
  

 

 

Sounds EITHER like

 

• a breakdown in lubrication due to high temps, or
   
   
  
• the engine was run at full throttle from dead cold (which MAY cause a seizure due to tight hot pistons contacting relatively cold, small bores), which doesnt fit the case here
   
   
  

 

 

 

If the piston/cylinder clearances are pretty tight to start with, and your lubrication is a bit suspect, then high revs & temps will expose any probs REAL quick.

 

If using premix in the engines, how often do you (re)shake the mix, to make sure there was no settling? (yep, not supposed to come out of mix, but I always used to shake my premix before refueling my bike)

 

And if using direct oil injection, maybe the injector wasnt delivering enough oil at high revs

 

And to quote Tomo,

 

But on take off, full power, and climbing (assuming) the airflow and power setting makes it hard to imagine any amount of cold causing a stoppage, on a water cooled engine

 

 

[Guest ozzie]

I have heard of 'cold siezure' some years ago. It occurred after the pilot had failed to warm the engine up correctly. At start the thermostate is closed and will circulate the water thru the engine only. The gauge will show an increase in temp. If you take off at this stage, when full power the water temp in the engine rises rapidly and the thermostate will fully open and allow cold water into the engine cooling it rapidly and nipping up the cylinders. Cure is to fully warm up the engine to full operating temp before applying full power.

 

 

[pudestcon]

All great posts here thanks guys,

 

A lot of issues to ponder on and think deeply about. At the moment all my information has come from a 5 minute phone conversation, so come the weekend I should have further (more accurate maybe) information on what exactly happened.

 

Cheers,

 

Pud

 

 

[Tomo]

warm up the engine to full operating temp before applying full power.

Probably a reason why they called it 'operating' temp eh? The people that don't think taking off is an 'operation' need to think again - taking off is probably the only part where the engine is putting it's whole heart and soul into the job. Please make sure the temps are all normal before opening that throttle.

 

Not saying that you don't already do that, it's just something I see on occasions, and it makes me cringe.

 

 

[facthunter]

the 912 series of engines.

 

David they are even worse. There is a pile of hoses connecting each cylinder head(only) and no real way of knowing what amount of coolant flow goes through which head. They are all in parallel.

 

In theory a car needs strict control of the engines temp by a thermostat, to get the temps where they should be. Rolls Royce had radiator shutters.in their cars. Big radials in aircraft have adjustable cowl gills. This not only gives the facility to get the head temps to where they should be, but it also reduces cooling drag to a minimum. In the automotive world if you want to ruin your engine, take out the thermostat. IF the engine runs cold the oil accumulates water that produces sludge anf the engine wears out prematurely. I would not recommend fitting a thermostat to an aircraft because it introduces another complexity.

 

Something else to go wrong. I have always been an advocate of manually operated cowl gills.re your query regarding the bypass, I do not believe that it would be available without an individual constructor doing it themselves . I personally would not rely on a thermostat. even with the bypass. . Nev

 

 

[Guest ozzie]

automotive thermostates, at least the ones i've replaced, have a small hole in them to allow a small amount of water flow. i assume that this is to stop the water pump from pressureising the block and head.

 

One of the functions of the thermostate is to control the flow of water thru the engine and the radiator. If you remove the thermostate the water flows too fast and it will not pick up the heat from the engine at the rate it should. Also in the opposite sense it will flow too fast thru the radiator and will not be able to transfer the heat to the air. eventually the water/coolant will slowly get hotter and hotter until something gives.

 

i find it hard to belive that the rotax engines may not come with a thermostat.

 

ozzie

 

 

[Guest ozzie]

Rotax 582 thermostat, Rotax 532 liquid cooled engine thermostat installation.

 

Just came across this. the whole section deals with the 582 page 18 for the installation of the thermostate. first up it states that the 582 is NOT shipped with a t/stat fitted. but says one should be in winter.

 

 

[Tomo]

automotive thermostates, at least the ones i've replaced, have a small hole in them to allow a small amount of water flow. i assume that this is to stop the water pump from pressureising the block and head.

It's actually there to stop vacuum as well. And to aid in filling. In vehicles with over heating troubles, you can drill out the hole a bit bigger instead of removing the t/stat completely - also.

 

 

[facthunter]

Hole in thermostat.

 

It's main purpose is to allow the system to be filled up with coolant after draining. If you want you can enlarge the hole and by not allowing complete blockage, you might help to eliminate thermal shock, but it will also taker longer to warm up. Circulating some water without it going through the radiator is the best. All modern cars do it, and most of them warm up very quickly, but it is recommended that they are not warmed up by idling as it takes too long and the wear takes place when the engine is cold. Moderate driving till temp is reached is the recommended technique.

 

The best thing to do with an aircraft to warm up, is to run at a fast idle facing downwind.

 

Getting back to the depicted failure, I would have to be convinced that the engine had enough piston clearance or was not running a bit lean on full throttle. These are the main causes of seizure in two-strokes. Sometimes carbon under the ring will cause the ring to break, but the result looks different. Nev

 

 

[Yenn]

And I thought the water cooling of Rotax was supposed to make it more reliable. How silly can I get?