"Cold seizure"

[dazza 38]

Thanks all, this thread has been very informative.I learn everyday.

 

 

[Methusala]

G'day All, blue head 582's come with a thermostat and a bypass as standard equipment, Don

 

 

[pudestcon]

I'm with you Dazza, I learn more and more everyday - at the start of this thread I used "Cold Seizure" because I didn't know if it was a commonly known thing or not. I've learnt so much here.

 

Pud

 

 

[Guest Wigg]

Thanks all up until this thread I had never heard of a "cold seizure". It has been a learning experience for me as well. Wigg

 

 

[pudestcon]

So to summarize.....

 

Warm the engine well to operating temps pre takeoff.

 

Ensure thermostat installed and in good condition.

 

Maintain and closely monitor temp gauges.

 

Don't be fooled! - 2 strokes will get carb icing in some conditions.

 

Oh! And don't forget correct fuel/oil mixture (maybe a bit richer than the book says) preferably mixed just before use.

 

Pud

 

 

[facthunter]

Oil Ratio and mixture

 

Pud on the last point, the fuel air/ ratio at full throttle should be such that the EGT's are as required by rotax. The readings can vary dependant on the instrument, but the full throttle temps should be a couple of hundred degrees below the ones reached at part throttle. It is funny to reduce throttle and have the temps rise but that is the way it works.

 

IF you had an oil pump and wished not to use it and go for an oil pre-mix instead, Or swapped carbs from a motor that was set up for an oil pump, you have to change the carb settings as otherwise the engine can lean out due to the reduced flow of fuel resulting from the addition of the oil. . This is important. Also if you add more oil than previously was the case the engine will lean out as well. It is necessary to be very careful and get the right amount , each time. Nev

 

 

[icebob]

Hi Pud,

 

Have seen this fitted to a 582's water cooling system,fitted over both carbies, thought you may be intrested.It is a kit from the USA(California power systems).

 

Bob.

 

 

[Guest Maj Millard]

The 600 plus hours I have done on a grey top 582 Drifter were with the Kawasaki KR250 Thermostat fitted. It always warmed up quickly (another purpose of the thermostat) and the temperature was always stable as a rock at 70c which is right in the middle of the recommended operating range. That engine is still in use and operating fine. The small hole at the top of the thermostat was described to me as a steam release hole to eliminate the build of of any steam pockets in the system which could disrupt flow of the coolant.

 

The 912 system is only for watercooling the heads and only runs around 2 Litres of coolant. It is symple, works well and obviously doesn't need a thermostat as there is none in the system. My 912 temps also sit steady as a rock mid range............................Maj..

 

 

[Guest terry]

The idea that a thermostat is shut tight one second and then fully open like a ball valve the next seems to run contrary to my understanding of it operation. I may be wrong but a thermostat in a mug of hot boiling water might enlighten us all.

 

 

[facthunter]

thermostat operation.

 

The older ones used alcohol in a bellows to operate them and the newer ones use a wax. They operate over a rather small range of temperature. Depending exactly where they are fitted the temp in the block may "overshoot" the thermostat setting and fully open quickly under the influence of the very hot water reaching the thermostat, allowing a surge of very cold water into the block rapidly. This is why you need the bypass circulation, to even it out. Some thermostats are "sticky" and cycle over a range, instead of modulating the temperature smoothly. I would rather not have one in an aircraft as it is something else to go wrong. Conversely I would not run a car without one except in an emergency (to get me home). or on a long trip where cold running is not a consideration. I have seen a lot of premature wear in cars where the thermostat was removed for an extended period. Nev

 

 

[Guest terry]

thanks facthunter, that reply broadens my understanding somewhat

 

 

[jetboy]

None of this has anything to do with "cold seizure" that commonly happens to 2 strokes when they blast off at full noise and then are throttled back too quickly at the top of the climb. It happens to air cooled and water cooled but the most reliably performing hand grenade engine in this regard is the Rotax 618.

 

It is thought to be a case of piston / bore expansion rates when the EGT suddenly goes up, and the engines normally run 'OK' after the forced landing event, but the scuffing has started the galling process in the bore and its only a matter of time things get worse.

 

Enjoy your thermostats, they just work better when there is water in the system.

 

Ralph

 

 

[Guest ozzie]

There is a test that engine reconditioners do to new thermostates when they fit them to their reco engines. slip a piece of cotton between the fixed and movable parts and place in water with a thermometer and bring it to heat holding the thermostate by the cotton. note the temp when the thermostate drops off the cotton and check it to the opening temp usually stamped on the thermstate body.

 

 

[pudestcon]

The most recent information I have on the engine seizure is that the engine stopped suddenly (did not slow down and then quit), it does not have a thermostat fitted, and the pilot/owner questions whether oil was added to the fuel when the tank was topped up. I haven't spoken with the pilot about this so have this information 2nd hand. The engine has not yet been dismantled. The L2 I spoke with still leans towards a cold seizure and says the last person to fill the tank was the owner. It will be interesting to find out the facts on this given I fly a similar aircraft at the moment and my aircraft (once restored) will be a T500 Thruster with a 582 blue head engine - same as the engine that failed.

 

Pud

 

 

[Tomo]

Is this engine oil injected? By the photo it looks like it is...

 

If it is, just check the breather on the cap of the container - we've had one seize up, up this way from that, the cap was completely air tight, so nothing came out of it.

 

 

[pudestcon]

Is this engine oil injected? By the photo it looks like it is...If it is, just check the breather on the cap of the container - we've had one seize up, up this way from that, the cap was completely air tight, so nothing came out of it.

It is but the owner prefers to pre mix the fuel/oil before filling the tank. I'm of the same mind in that if you mix the fuel manually you know that the mix ratio is correct - what happens if a fault develops in the mixing system such as what you have described? Seizure as you say!!

 

Cheers,

 

Pud

 

 

[Tomo]

Indeed, but I hope the oil injection is disconnected! ;) You'll end up with a double dose of oil otherwise.

 

 

[pudestcon]

Indeed, but I hope the oil injection is disconnected! ;) You'll end up with a double dose of oil otherwise.

Yep, all good there. I have heard of some owners running there Rotax on 40:1 which is more than the recommended fuel/oil ratio of 50:1. That's a long way from the ratio that you are alluding to though Tomo.

 

Pud

 

 

[Guest ozzie]

If you pre mix and use more oil than is recommended you are actually leaning out the mixture. the extra oil in the mix takes place of fuel and runs leaner.

 

 

[pudestcon]

If you pre mix and use more oil than is recommended you are actually leaning out the mixture. the extra oil in the mix takes place of fuel and runs leaner.

Point taken Ozzie but bearing in mind my 1st post regarding my mechanical prowess....

 

What sort of consequences could I expect from running a Rotax 582 at 40:1 instead of the recommended 50:1 ratio? Incidentally, the engine is run on standard unleaded petrol; that's 91 RON I think.

 

Pud

 

 

[facthunter]

Oil Mix

 

Pud, I know I am cutting in here but I did mention this problem in an earlier post. Straight petrol flows easier than petrol with oil in it . The mix has a higher viscosity. IF you start to change oil mix ratios you will change the mixture and lean mixture is deadly to two strokes. I mentioned the situation where the carbs are set up for use with an oil pump and then go to premix. You will run lean. Your EGT's should give you a proper temp reading IF they are too hot, enrichen the mixture. Raise the needle for midrange and use a bigger main jet for the full throttle position. Tether the plane and ground run it. Swap your EGT's over to check that the readings are consistent. I don't think that 91 octane would give you enough resistance to detonation, which should be avoided and always use fresh mixed fuel/oil. Mixed fuel goes off quicker than unmixed so don't keep it long. Using more than the recommended oil ratio is not an advantage, as long as the engine is warmed up. Make sure the plugs are exactly as recommended. Look after your 2-stroke and it will look after you. Nev.

 

 

[pudestcon]

Thanks Nev,

 

I don't think you are cutting in and certainly no need to apologise. I take what you say as information gained for me to make sense of a subject I know very little about, and need to learn as much as I can if I'm to take good care of my aircraft when the time comes.

 

Cheers,

 

Pud