oil running hot

by wayne silvan in 912 / 914 Technical Questions 11 years ago

Have a problem with a 912 80 hp.The aircraft just completed a 1400 mile trip from Texas to Mt. and flew flawless and at the last 80 miles the oil temp started coming up from 190 to 230 f and the oil pressure dropped from 50 psi to roughly 35 psi.changed oil and still the same.Is there a possibility that the oil bypass could be stuck open? Also this engine doesn't have the compensation tube like my 912 100 hp is it suppose to?Thanks

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Re: oil running hot

by jan kerstens » 11 years ago

jan kerstens

34 131 5

Hi Wayne,

Do you have a thermostat installed? If so you could remove it to see what happens. Please note that in this case you have to purge the oil system, see the ROAN instruction video how.

Thermostats can be fail albeit very rare. What is the make?

Good luck Jan

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Re: oil running hot

by bill martin » 11 years ago

bill martin

10 757 0

Wayne,

Jan is right. Oil thermostats rarely fail and if they do, they cannot stop oil flow through the engine. Are the cylinder head temps OK? Water temps OK?

Yes, you should have a compensating tube on the 80hp engine.

Bill.

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Re: oil running hot

by wayne silvan » 11 years ago

wayne silvan

7 17 23

No oil thermostat and the engine is running cool 180-200.Wonder if maybe the sending unit is bad I will check at the filter with a temp gun and see.Although the loss of power does bother me some I think I will do a compression check on it to make sure there are no valves sticking on it.During the 1400 miles the pilot didn't have much choice of fuel at some airports so it got a good shot of 100LL maybe that could be the cause, oil was very black when changed approx 25 hours on the oil.And yes I will be putting on the tube figured it should.

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Re: oil running hot

by bill martin » 11 years ago

bill martin

10 757 0

Wayne,

One quick way to check the sender is to switch the cylinder head temp sender with the oil temp sender. They are the same sender. The cyl. head sender is not actually in the water jacket and can be removed without losing any coolant. The oil temp sender can be changed without purging the oil system. It is an easy switch. It sounds like it is not the sender however. under normal conditions, as the oil temp goes up, the oil pressure goes down and your gauges are indicating that.

Maybe the oil filter or the oil pressure regulator?

Bill.

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Re: oil running hot

by wayne silvan » 11 years ago

wayne silvan

7 17 23

Bill we replaced the oil filt when we changed the oil.I believe this engine had the 95 hp upgrade done with aftermarket pistons installed and I'm wondering if that could be part of the problem as if maybe a piston is going bad I'm going to do a compression check on it when I get a chance.And yes I am also wondering if the bypass is possibly stuck leading to the low pressure and also the increase in oil temps.The type is 912 ul.

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oil running hot

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