Air Leak From Exhaust Port of The Vaccuum Venturi Assembly

[Carl Tesch]

I am an instructor in a Diesel Technical school. We are working on a Newell Motor Home which belongs to the Governor of South Dakota. We have all the information we need to work on the brakes, engine, gen set, etc. ; but very little technical information on Newell itself.

I am trying to repair a constant air leak from the exhaust port of the vaccuum venturi assembly which I think supplies vaccuum to the heater/defroster blend doors. I have purchased a new venturi assembly and it acts the same as the old one. I have used a hand vaccuum pump to supply vaccuum to the "S" port but this still does not close the valve. Any suggestions? Can you tell me how this device is supposed to work?
thanks for your time and attention.


Thank You,
Carl Tesch

[TechTalk]

The device you describe is a vacuum generator used on older model Newell coaches. It uses a small amount of air pressure to produce vacuum to operate the heater controls. What you are hearing under the front of the coach (just behind the front bumper) is normal as the device continually exhausts a small amount of air.

[Carl Tesch]

Thanks for your answers. Here is a post script: After trying two new valves which acted the same as the original, i concluded that the valve was manufactured incorrectly. I carefully pried the cover from the valve, cut about 1/2 inch from the spring and reassembled the valve using RTV as sealant. The valve now works correctly. It exhausts air as it is building a vacuum in the reservoir. When the vacuum reaches about 18 in. Hg. the valve shuts off and no more air is exhausted. It will remain in the shut off position until the heater controls are operated. Vacuum is used by the blend door motors and then the valve goes into action and generates vacuum

If anyone is interested in this repair, I am willing to share my information. This is such a great website for us DIY guys.

Thanks again,
Carl Tesch