Coolant and oil temps

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BurtAugust
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Coolant and oil temps

Post by BurtAugust »

I can control the coolant temps and keep them below max fairly easily. But the oil temp seems to run at the high end of the range; particularly if you use rpm settings above 2400. Any thoughts on how to control this ?

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Scott - A2A
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Re: Coolant and oil temps

Post by Scott - A2A »

It's really the high end of the gauge, but not necessarily high. The oil cooler airflow is controlled with the main cooling flap handle. Also, keeping RPM's down is always a good idea. Your cruise can be much less than 2,400 RPM.

Scott.
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Zacke
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Re: Coolant and oil temps

Post by Zacke »

Hey guys,

is the oil cooler really controlled with the cooling flaps or do the these flaps only cool the coolant? I wonder what the scoop under the fuselage behind the oil cooler is good for? It seems it bypasses the cooling flap system.

Thanks in advance,
Zacke

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Jacques
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Re: Coolant and oil temps

Post by Jacques »

Zacke,

As far as I remember the oil cooler and engine coolant are in the same location, so both are cooled by opening up the flaps that you mentioned behind and under the engine.

Zacke
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Re: Coolant and oil temps

Post by Zacke »

From the "erection and maintance" manual of the N-modell:

"A thermostatically controlled rotary type oil temperature control valve mounted on top of the oil cooler controls the flow of oil from the engine through the oil cooler. In operation, the helix bimetal thermostat rotates the rotary valve, allowing the tempered oil to flow through the warm-up passages or the core section of the oil cooler depending upon the operation conditions."

So it's still not clear to me: Yes, there's a thermostat. It sounds to me it controls the way the oil goes to different sections of the oil cooler which deliver different amount of cooling. Maybe less cooling when the oil is cool (after starting the eninge) and full cooling when the engine's warmed up.
I'm still confused if the air flow controlled by the cowl flaps is only directed through the coolant radiators and the oil cooler receives an unrestriced air flow through the front inlet and then trough the scoop behind the oil cooler (bypassing the cowling flaps).

Regards,
Zacke
Last edited by Zacke on 22 Aug 2021, 02:47, edited 1 time in total.

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Jacques
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Re: Coolant and oil temps

Post by Jacques »

The thermostatically controlled valve for the oil sits atop the oil cooler (from what my eyes can see!) and, if I read the description correctly, it either sends the oil directly back to the engine (cold) or allows it into the oil cooler (hot), depending on the temperature sensed by the valve. The oil cooler itself is installed in a “support and strap assembly” attached to, and under the two coolant radiators.
When you open the cowl flaps you are directing more air to all three cooling assemblies - the two coolant radiators and the oil cooler slung beneath them. So opening or closing the cowl flaps affects both systems directly.

Zacke
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Re: Coolant and oil temps

Post by Zacke »

Jacques, thanks for your reply.

Do you know what the scoop behind the coolers that runs along the fuselage is good for?

Regards,
Zacke

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Jacques
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Re: Coolant and oil temps

Post by Jacques »

I think you are taking about the cowl flaps themselves. They trail behind and under the nose and restrict or increase the amount of air passing through the oil and coolant coolers.

Zacke
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Re: Coolant and oil temps

Post by Zacke »

No, I'm talking about the sccop that runs along under fuselage till about behind the wing.

Sorry, I don't know how to post screenshots here in the forums.

Regards,
Zacke

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Jacques
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Re: Coolant and oil temps

Post by Jacques »

Ohhh, yes I see what you’re talking about. I can’t find anything on that…so just a guess but it could be a channel for fuel vent lines and/or drains. It kind of looks like there is a small opening for air to flush through to the back. A complete guess on that one, though! :D

Zacke
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Re: Coolant and oil temps

Post by Zacke »

Ok, thanks! :D

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