High pitch whine heard from back of coach

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High pitch whine heard from back of coach

May 24, 2017, 03:13:38 pm

I am usually the "tail gunner" watching where the backside of our 30' is while we back up. The other day I took notice of a high pitch whine coming from the coach while the engine is running. Come think on it I might have heard it before in the same setting. Parking in our driveway access surrounded by two walls and concrete. Don't recall hearing when running up on blocks at open air campsite.

Having read the terror of a blown fuel pump, I'm asking if this whine is normal or a symptom of a tired pump about to cause my check book to scream in agony?!

Thanks
Lydia

Re: High pitch whine heard from back of coach

Reply #1 – May 24, 2017, 04:10:36 pm

Sometimes it's difficult to pinpoint the location of a noise (and you know that the noise will vanish the nanosecond that the tech attempts to hear it!), but maybe this article will help narrow down some possible causes:

Seven ways to pinpoint that high-pitched, whining noise

Please post when you diagnose the cause of the whine!

Re: High pitch whine heard from back of coach

Reply #2 – May 24, 2017, 05:42:16 pm

Are you sure there are no teenagers nearby?

Re: High pitch whine heard from back of coach

Reply #3 – May 24, 2017, 05:43:43 pm

High frequencies are pretty directional. Low frequencies can appear to come from 'everywhere'. So a good technique is to get in an open area, away from traffic and singing bugs/birds, and cup your hands behind your ears. See if you can localize it that way, experimenting with engine running in park, in gear, in reverse, creeping with brakes on, backing freely at idle, etc. Your concrete parking alley is great for emphasizing/noticing it, but not great for localizing it.

I do know that brakes have 'screechers' that are designed to squeal when a certain wear point is reached. That's worth a look unless your brakes are known to be new. Many other rotating engine bits can join the chorus, too.

Sometimes making a recording with your phone while in the proximity of engine, brakes, etc. can reveal sounds on playback that were masked or unnoticed at the time. Headphones and a quiet environment will help.

Keep the 'operating' and 'observing' roles the same. Women generally have better high-frequency hearing than men, and you'll want the vehicle operating conditions to be the same as they usually are.

Chip

Re: High pitch whine heard from back of coach

Reply #4 – May 24, 2017, 06:46:13 pm

Had a similar mystery noise on my '08 LD.

Turned out to be the carrier bearing. Apparently a fairly common E-450 problem.

Have someone drive very slowly. Have someone walk next to the RV by the rear axel and listen for a squeaking noise each time the drive shaft turns.

Ed

Re: High pitch whine heard from back of coach

Reply #5 – May 25, 2017, 11:46:39 am

If the squeal is happening when the coach isn't moving, take a look at the water pump. They will squeal in their final death throe prior to freezing.

HD

Re: High pitch whine heard from back of coach

Reply #6 – May 25, 2017, 12:22:56 pm

Lydia

Can you better pinpoint the noise?
Was it in the middle or rear of the coach?
If in the middle, and it only appear when moving, check the driveshaft carrier bearing.
At the rear of the interior, do you hear it when the rig is standing still and the engine is running? If so, check the fuel pump.
The fuel pump only runs for a second or two when the key is turned on and the engine isn't started.
Once the engine has started, the fuel pump run continuously.
FYI - always run a 1/4 full tank of fuel or more. The fuel pump has very small motor that sits in the bottom of the gas tank, and cooled by the fuel. If the fuel level gets too low, the pump can overheat, especially on hot days.

Did you get the shock bushing information I sent you? They will replace the Bilstein top bushings.

Larry

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