High Revving, wtf?
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Laughing Gas
Joined: Feb 2004
Posts: 1,200
Likes: 4
From: Ottawa, Ontario Canada
High Revving, wtf?
I noticed a few times that after starting the 5.0L engine, I hear a noise that sounds like high revving. Happens for example during multiple starts for short trips, like when shopping at multiple stores in close proximity 20 min trips apart. Lasts for a minute or two, and engine is already pretty warm from previous trip so why does it need to rev up? The climate system is switched off.
Not really sure if it is the engine running faster in short bursts, or some other "system" under the hood speeding up and then slowing itself down.
Is this normal or a problem developing??
Not really sure if it is the engine running faster in short bursts, or some other "system" under the hood speeding up and then slowing itself down.
Is this normal or a problem developing??
Senior User
Joined: Jun 2016
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From your description I would say this is the engine fans.
When you're driving around for extended periods, the coolant is continuously circulating between the radiator and engine block and being cooled by moving air. When you stop the engine at temperature, the engine temp actually rises beyond operating temperature before it begins cooling off because the flow of coolant has stopped and there is no air moving across the radiator, but there is still some heat transfer occurring from the combustion process. You may notice that your temperature gauge is above normal operating range when hot starting, so your fans kick into high gear for the beginning of your trip to get things back into normal range. Once the engine is cooled back to normal range, the fans slow back down to normal RPMs until another hot-start condition. This is all normal operation.
When you're driving around for extended periods, the coolant is continuously circulating between the radiator and engine block and being cooled by moving air. When you stop the engine at temperature, the engine temp actually rises beyond operating temperature before it begins cooling off because the flow of coolant has stopped and there is no air moving across the radiator, but there is still some heat transfer occurring from the combustion process. You may notice that your temperature gauge is above normal operating range when hot starting, so your fans kick into high gear for the beginning of your trip to get things back into normal range. Once the engine is cooled back to normal range, the fans slow back down to normal RPMs until another hot-start condition. This is all normal operation.
Super Moderator
Joined: Jan 2008
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From: Maine, Virginia
You should hear the fans on my daughter's 2015 Fusion 2.5L, sounds like a turbo prop plane coming in for a landing. I second the fans.
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Laughing Gas
Joined: Feb 2004
Posts: 1,200
Likes: 4
From: Ottawa, Ontario Canada
sounds like the jury says it's the fans so I'll buy the verdict. ;-) Just wondering why we never heard this before on any of our previous F150 8cyl trucks (2003, 2006, 2011) or is this fan system contraption a recent invention and unique to current models?
So where are these fans anyway and can they be seen under the hood? Anyone got a pic?
So where are these fans anyway and can they be seen under the hood? Anyone got a pic?
Lead Driver
Joined: May 2015
Posts: 5,873
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From: Mts. S. of San Francisco
What I'm hearing is the fan(s?) behind the radiator. Most new designs have electric fans behind the radiator that are controlled by the computers in charge.
Certified Thread Hijacker
Joined: Aug 2001
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sounds like the jury says it's the fans so I'll buy the verdict. ;-) Just wondering why we never heard this before on any of our previous F150 8cyl trucks (2003, 2006, 2011) or is this fan system contraption a recent invention and unique to current models?
So where are these fans anyway and can they be seen under the hood? Anyone got a pic?
So where are these fans anyway and can they be seen under the hood? Anyone got a pic?
Also, the fans ramping up on engine restarts caught me off-guard a time a two after buying my truck.
Josh
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302grabber
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Jun 5, 2007 04:46 AM