582 high engine temp

by Michael Regan in 2 Stroke Technical Questions 11 years ago

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Re: 582 high engine temp

by Michael Regan » 11 years ago

Michael Regan

5 96 0

Been out of action for a couple weeks but finally got some more done on this heating problem. Unfortunately all my efforts so far have fallen short. THIS IS WHAT i DONE SO FAR.

Checked correct temps on gauge by dipping the probe/sender and 2 separate thermometers in water and noted temps on all three while it boiled and they all matched perfectly... so my gauge is spot on.

Then removed thermostat and tested in a climb and although it still reached 185 degrees at WOT over 1500' climb ... it did cool quickly at cruise all the way back to 150. No problem with it cooling too far. Never got below 140 all the way to the hangar door.

Remembering that the mixture is done in three stages, I decided to up the main jet from 165 to 170 to see if it would effect WOT temps... but it made no difference at all.

Because the larger main jet made no difference, and the EGT's are always normal, I am thinking there is definitely no problems with air/fuel mixture.

I then turn my attention to the radiator system. I reduced the coolant mix from 50/50 to 25% coolant and 75% water, and filled with the correct amount which is 2.55 liters. I then purchased a new thermostat ($148 delivered...wow) and installed it. Checked the water pump impeller was ok and clear of debris. Installed new spark plugs just for good measure, and took her for another test.

OAT ................85 deg
Take off temp .....135 deg
Climb to 300 feet..170 deg
Climb to 500 feet..185 deg and still rising.

Got it back to 180 deg in the circuit and after landing could not get it below 175 even after 7 minutes of 1900 rpm idle. Switched off at this temp (yeah I know its not good).

Back to the drawing board. Maybe I need to take the head off now. BTW... could too much carbon buildup on the pistons caused over heating?

Thanks for listening.... mike

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Re: 582 high engine temp

by Nick Axworthy » 11 years ago

Nick Axworthy

16 325 0

Are your rads upto the job and big enough....and clear internally,

What RPM does the engine make WOT...if the pitch where to course that can lead to overheating.

Thank you said by: Michael Regan

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Re: 582 high engine temp

by bill martin » 11 years ago

bill martin

10 757 0

Mike,

It is sounding more and more like you simply don't have enough radiator. One quick and dirty way to find out is to leave the cowling off the plane and take a flight. I'll bet it will make a difference.

You can check the carbon buildup a couple of ways. Best way is to pull the exhaust manifold and you can see the entire top of the piston. Only other way is to use a scope and look through the spark plug holes. The piston tops will usually be mostly black with some bare metal showing here and there. Usually if you have a carbon problem, you will see it on your plugs too. With carbon buildup you can also see stuck rings, detonation, backfiring, and other things. If you pull the manifold you can check the rings at the same time. It is hard to see them move but there are tricks you can use. I run the piston up until the rings are exposed, then dip my finger in some two cycle oil and smear it heavily on the exposed rings. You can then rock the crank slightly up and down and see the oil squeezing in and out of the top and bottom of the ring as it moves in the groove. Unless you have been using some bad fuel or the wrong type of oil, you probably don't have a carbon problem.

Keep trying, you'll find the answer. Remember Aachem's razor; The simplest solution is usually the correct one.

Bill.

Thank you said by: Michael Regan

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Re: 582 high engine temp

by George Gennuso » 11 years ago

George Gennuso

0 4 0

Have you considered making baffels to direct the air through the radiators? I have a Pulsar with two radiators mounted behind the prop. I had an over heating problem and tried all that you have tried, didn't help much. Two things worked best for me. I reduced the anti freeze to a 10% mix and I built fiberglass baffels that directed 100% of the air through the radiators. Now it is hard to get above 165 degrees.

Thank you said by: Michael Regan

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Re: 582 high engine temp

by Michael Regan » 11 years ago

Michael Regan

5 96 0

Nick,

The WOT RPM is 6000 now, but used to be 6700 once upon a time... it lost 700rpm a few months ago and I don't know why. About 2 months ago it came back to 6400, but now its back to 6000.

For the propeller pitch to pay a part it would have to have changed on it's own because I never touched it at all. Is this possible? Can it go back and forth? I did look at it and found it to be solid and cannot move any blades by hand, so it appears I can rule that out I hope.

Please view pic of radiator attached. It is a twin (one each side of prop) I did send a pic to my Rotax man here in Oz and he said it is NOT a rotax radiator, so maybe it is the problem after all. Can anyone with twin rads please compare it with mine and tell me if the size is the same? The twins I see in diagrams appear longer, but I dont know how they could fit underneath my cowl.

Radiator_Avid018.JPG (You do not have access to download this file.)

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582 high engine temp

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