 What do the air plenum flaps do? |
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| Grosbard |
 Mar 30 2021, 04:33 PM
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#1
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Member  Group: Members Posts: 88 Joined: 29-September 09 From: Pasadena, CA Member No.: 10,862 Region Association: Southern California 
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Hi all! I'm curious what the air plenum flaps do, and I'm hoping someone can educate me, please. I'm referring to the parts mentioned in this thread:
http://914world.com/bbs2/index.php?showtopic=349044 My guess is that they prevent water and rocks and other stuff from getting to the air-cooled fan...am I correct? Would missing these flaps hurt engine cooling? (I can't see how, but I might be missing some part of the picture) Also, what makes the flaps open? Just the low air pressure on the intake side of the fan? Thanks for your help! |
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| brant |
Mar 30 2021, 04:36 PM
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914 Wizard Group: Members Posts: 12,008 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
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I didn't check your link...
but if your talking about the air flaps on the motor nothing to do with water... they are responsible for diverting the cool air over your oil cooler do not remove them unless you want to burn up your engine make them work... ideally with a thermostat the thermostat and spring pressure are what make them work |
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| Grosbard |
Mar 30 2021, 04:44 PM
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#3
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Member Group: Members Posts: 88 Joined: 29-September 09 From: Pasadena, CA Member No.: 10,862 Region Association: Southern California
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Hi @brant . No, I'm talking about the flaps on the intake side of the cooling fan. It's hard to describe them, but that link has a great photo. Or this photo from 914rubber is also good (parts #19 and 20 on this photo):
https://914rubber.com/914/914-engine/air-cooling |
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| Mark Henry |
Mar 30 2021, 04:55 PM
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#4
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Yes they work on air pressure and yes they actually do work.
The heat exchangers have two sources of fresh air, the crank fan and an electric fan. With the electric fan on it opens and closes as the engine goes from idle to higher speeds, it maintains a more constant air pressure. |
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| Grosbard |
Mar 30 2021, 05:01 PM
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#5
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Member Group: Members Posts: 88 Joined: 29-September 09 From: Pasadena, CA Member No.: 10,862 Region Association: Southern California
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QUOTE(Mark Henry @ Mar 30 2021, 03:55 PM)  Yes they work on air pressure and yes they actually do work. The heat exchangers have two sources of fresh air, the crank fan and an electric fan. With the electric fan on it opens and closes as the engine goes from idle to higher speeds, it maintains a more constant air pressure. Ah, thank you Mark! So let me rephrase to make sure I understand properly: The presence or lack of flaps doesn't affect engine air-cooling. They're just there to be able to heat the cabin at low engine speed when there isn't enough air flow from the engine air-cooling fan. |
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| barefoot |
Mar 30 2021, 06:07 PM
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Senior Member Group: Members Posts: 1,409 Joined: 19-March 13 From: Charleston SC Member No.: 15,673 Region Association: South East States
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Ah, thank you Mark! So let me rephrase to make sure I understand properly: The presence or lack of flaps doesn't affect engine air-cooling. They're just there to be able to heat the cabin at low engine speed when there isn't enough air flow from the engine air-cooling fan. [/quote] Correct, with electric heater fan on with engine speed low, they close to force more air thru the heat exchangers for cabin heat |
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| GregAmy |
Mar 30 2021, 06:54 PM
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#7
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Advanced Member Group: Members Posts: 2,505 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States
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To further clarify...they're simple doors that close to force the electric blower fan airflow into the heat exchangers instead of bleeding into the fan housing (an easier route, especially at low RPMs.)
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