cylinder head temperatures

by philippe marquie in 912 / 914 Technical Questions 7 years ago

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Re: cylinder head temperatures

by philippe marquie » 7 years ago

philippe marquie

1 5 0

I understand roger, but if there is really a problem of temperature I will not know it by changing sides of the wires;
the engine is new and never worked ,maybe the cooling is not good, fluid problem or other?
I'll keep you informed

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Re: cylinder head temperatures

by Andrew Dunning » 7 years ago

Andrew Dunning

1 31 86

If your Rans S6 has the radiator above the carbs, removing all of the air from the cooling system can be quite difficult.

I will try and find the link on how to bleed the system.

Andrew

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Re: cylinder head temperatures

by Roger Lee » 7 years ago

Roger Lee

126 5.14k 4.58k

Ma traduction? :)

Salut Philippe,
Tout ce que vous faites en changeant les fils est un petit diagnostic. Supprimez d'abord s'il s'agit d'un défaut de câble ou d'un défaut du capteur. Si ceux-ci vérifient bien, alors suspectez un problème de liquide de refroidissement. L'échange des fils est facile et ne coûte aucun argent pour diagnostiquer. Le diagnostic est un art perdu. Vous devriez toujours commencer par le plus commun, facile à vérifier et le moins cher d'abord. Commencez par "A" puis déplacez-vous vers B alors C puis D dans un ordre logique. La plupart des problèmes avec un Rotax ne sont pas des problèmes exotiques, mais des corrections très simples. Si vous démarrez la ligne à la lettre "F", vous avez peut-être réussi votre problème facile avant et peut prendre une semaine pour le trouver au lieu d'une heure et vous pouvez payer de l'argent que vous n'aviez pas à faire.

En ce qui concerne le système de refroidissement. Assurez-vous que votre réservoir d'expansion sur le moteur est plein. J'espère que vous utilisez un mélange de réfrigérant 50/50 et pas Evans. Evans porte une pénalité de 20F - 30F. Un milieu d'eau est mieux pour absorber et dissiper la chaleur. C'est une des raisons pour lesquelles les services d'incendie l'utilisent, en plus, il est abondant et peu coûteux à utiliser sur les incendies.
Si le réservoir d'expansion vérifie complètement vos tuyaux de refroidissement et assurez-vous qu'aucun flexible n'a un rayon réduit. Il se peut qu'il ne soit pas complètement déformé, mais peut être pincé, ce qui ralentit l'écoulement, ce qui permet de conserver la chaleur.

Salut Philippe,
All you are doing by switching the wires is a little diagnostics. First rule out if it is a wire fault or sensor fault. If these check out fine then suspect a coolant issue. Swapping the wires is easy and doesn't cost any money to diagnose. Diagnostics is a lost art. You should always start with the most common, easy to check and least expensive first. Start at "A" then move to B then C then D in a logical order. Most issues with a Rotax aren't exotic problems, but very simple fixes. If you start down the line at letter "F" you may have passed your easy problem right up front and may take a week to find it instead of an hour and you may pay money that you didn't have to.

As far as the cooling system goes. Make sure your expansion tank on top of the engine is full. I hope you are using a 50/50 coolant mix and not Evans. Evans carries a 20F - 30F temperature penalty. A water medium is better for absorbing and dissipating heat. That's one reason fire departments use it besides it's plentiful and cheap to use on fires.
If the expansion tank is full look at your coolant hoses and make sure no hose has a reduced radius. It may not be kinked all the way off, but may be pinched down which slows flow which helps retain heat.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: cylinder head temperatures

by Kevin Machniak » 7 years ago

Kevin Machniak

6 167 40

I like Rogers idea of swapping the wires for diagnosing.
All that will happen is the # 2 cylinder temperature will be shown on the gauge as #3 cylinder. If it is still erratic then its the wiring.
The sensors are in coolant , so if you don't have to remove them the better .
You could also use a laser thermometer to verify the head temps.

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Re: cylinder head temperatures

by Bill Hertzel » 7 years ago

Bill Hertzel

13 1.95k 7.96k

...the cylinder sensor n 3 (rear) indicates normal temperatures (80-90degress after 3 minutes, steady rise);
the cylinder n2 (front) rises up to 120 degrees then lowers to 100 then goes back to 120 then lowers to 100, etc; is it normal, it is a use between 1800 and 3000 rpm and on the ground.
...

I am going to argue the other side of the sensor...
He is on the ground at a high idle. Nose UP.
The front Left Cylinder is repeatedly bouncing between 100 and 120°C

If the sensor is sitting in an air pocket, the cylinder head temperature will rise until it reaches the boiling point of the coolant. ~120°C ???
Once it starts boiling it splashes all over the air pocket and cools the head.
The boiling stops the head heats up again, and the cycle repeats.

Swapping the wires it fine to eliminate the wiring, but that does not mean the sensor is electrically faulty.
It just means that, faulty or real, the indication is coming from the sensor.

The repetitive nature of the fault and the suspicious temperatures point to air in the cooling system.
This is a new (never flown???) plane.

Getting the engine in a nose down attitude may clear the air pocket and make the problem disappear.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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cylinder head temperatures

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