Whistling Willy underneath my Esprit

[Herbert Harvey]

I have had my 1989 Lotus Esprit Turbo for maybe 3 years now, mainly at idle there has always had a  Chirping or Whistling sound coming from underneath the Engine. Today I took a Stethoscope and found the culprit. There is a black rubber hose underneath the driver side (USA Specs) strapped to the bottom of the frame. Its not the Engine Crank Case Breather tube which is on the opposite side of the Engine. This rubber hose is blowing air out almost as if it were exhaust. I  traced it to were it disappeared somewhere around the back of the firewall and engine.  In the next few days I plan on jacking up the car and crawling underneath to figure out exactly were this "breather hose" is coming from.

So point being this hose has like a whistling effect almost like if one was to blow on the top of a beer bottle.. Sounds Cheap and uh just not right. I of course do not want to do anything to hinder its function, However I was wondering if i cut a notch in it possibly the whistling effect would change" Can I put some kind of little muffler on the end of it? Anyone have this experience? I am pointing at it with the handle of a Garage Magnet in the photo attached..  any thoughts of suggestions much appreciated!

[Barrykearley]

It’s the exhaust from the vacuum pump 👍

[CHANGES]

Some people put a filter on the end to help quieten  it..  Not all make a noise its just how it is.. 

[CarBuff]

Yup, a small fuel filter clamped to that hose will quiet it down without affecting performance of the vacuum pump.

 

Replacement vacuum pumps are available from Rock Auto in the USA. The new ones don't even have an 'exhaust' port.

 

[Glyn Harper]

Are you getting decent vacuum? If it's really noisy, it could be because the diaphragm in the pump has given up. Happened to mine and sounded like a load of quacking ducks.

[Herbert Harvey]

Glyn Harper, CarBuff, CHANGES,, BarryKearly, 

Thank you for all the information! I am glad to hear that I can do something to muffle the Whistling sound. I am of course very concerned that the diaphragm has failed as "Quaking Duck" is a better description of the sound i am hearing. The weird thing is that the noise really seems to be made from the end of the hose, Like i said before same kind of effect like blowing over the top of a beer bottle. 

Next step is going to have to be to test the vacuum pumps performance which I am not entirely sure how to do at this point but  with some research i can figure that one out. Thanks again everyone!  the Comradery on this Forum is amazing, I wish there was some kind of a Event were Esprit Owners from all over the world were in one place so I could meet everyone. 

[Barrykearley]

Pull the under tray off - look for the tee piece - test vacuum - about 0.69-0.71 is fine.

you could always do it at your brake servo as that’s probably easier

[CarBuff]

Book spec for vacuum pump is 18 HG.

 

Our pump used the small fuel filter to muffle the sound for about 12 years with no operational effects. I did an engine-out engine/gearbox refresh and changed it out then.

 

The pump cross-ref is General Motors' 7844038. NAPA sells them as item # 641006. Some fettling is required to make them work.  (As usual, with Lotus repairs) 😁

[Herbert Harvey]

Thank you Barry and Atwell,

Thats very helpful, was planning on taking of the under tray and getting a good look at the vacuum pump , look for leaks.. Now I know to test it and what to hope for with vacuum. Will post my findings, thanks again everyone.

Chris Herbert