Harmonic sounds in 07 Diesel Winnebago Tour?

[fotoguy]

Fellow RVers

I have an issue with my 2007 Winnebago Tour 40’ motorhome. I am the 2nd owner at 9000 miles and currently have 13,000 miles on the odometer. I have always heard a rotational hum or harmonic sound from the front of the cab while driving down the road in 6th gear between 55-65mph. This occurs while there is a light load from headwind or slight uphill. When I let off the gas the sound stops. If I downshift one gear at the same throttle position the sound goes away.

The coach has been to 2 Freightliner shops and the first dismissed it as an exhaust noise. The second shop has been much more diligent and has found several problems, but has not solved the harmonic sound. They have checked the ride height and angles, engine positions and many other measurements to check factory specs. They found that the driveshaft had collapsed (no free play in length, both long an short)and that the shaft installed was too long. Shaft was replaced and still the same sound. They had the District Service Manager and mechanic test ride and found some vibrations near the rear of the coach. They sourced out the 4 rear tires and rims to check balance and found an out of round wheel tire combination and corrected. Less vibration according to techs, but still the same sound.

Any suggestions on a solution or other areas to check. Factory thinks that everything is within specs and Winnebago didn’t insulate the coach enough from the chassis or they did something wrong installing the body. Help Help, it been in the shop for 4 weeks.

[DriVer]

Quote:

Originally Posted by fotoguy Any suggestions on a solution or other areas to check. Factory thinks that everything is within specs and Winnebago didn’t insulate the coach enough from the chassis or they did something wrong installing the body. Help Help, it been in the shop for 4 weeks.

Winnebago is a very good coach builder and surely a lack of insulation would have been reported here before now since there are many Winnebago owners here. I'm hoping that you're not going to get into a finger pointing situation and that they'll find the problem. I'm thinking that a driveline noise event like you're describing isn't going to be lessened by any amount of insulation that makes sense.

I had a bad vibration situation in a vehicle that I owned and it was found to have been the tires were not true. I'm just wondering if perhaps you might want to go and test drive a 2nd coach out of curiosity like you have to perhaps rule out whether the sound is in common with 2nd coach or not.

[RVThere]

I have the same year Tour and the 40TD model. I have close to 20k miles and no vibration.

Just a wild guess, but have they checked the seals of the front cubby? Maybe a leak is causing the door to vibrate? But that wouldn't explain why it stops when you change transmission gears.

Do you still get the vibration when the genset is running and you are driving?

Good luck!

[bdpreece]

Stupid things to try if you have not already done so.

Remove wheel covers
Tape over the grill tubing
Tape over front compartments
Then take it for a test drive

I am not familiar with your coach but I have read posts before on vibration noises and a lot of times the noise is one of the above problems.

[ernieh]

See reply to your question on RV Net.