whistling sound?

hi y'all
looks like a great site.
hope someone can help, i've a dx engine in my mk1. recently it has been running for a while and then stalling. when it is running i can hear a faint hissing sound somewhere in the engine bay?? could this be the problem??
thanks

Not sure to be honest, but I'm sure someone here will know!

Welcome by the way, any pics for us to see of your MK1?

Andy

no pics yet...is looking abit shabby at the moment anyway..once weather gets bit warmer will get to work tidying her up a bit

yep had the same problem with mine. Turned out to be a loose bolt on the inlet manifold

checked them a while ago but will have another look
thanks…

I had something similar - a vacuum pipe had come disconnected from somewhere - look for a clean spigot in an otherwise dirty engine bay - then feel around for any loose pipes.

It could also be a hole in any of the vacuum pipes - they do become perished, then crack and eventually hole with time.

There are pipes over, around and behind the engine. I suggest you run it and then listen carefully to work our where it's coming from.

Oh - and check that the air bypass valve is connected (electrically) under the back of the intake manifold.

Hope this helps


Ali Cabrio

thanks for all the advice, will have a look this weekend...

had a look this morning and couldn't see anything obvious. just a couple  of things i need to double check with people really. (i've taken some photos to try and explain exactly what i'm looking at) on top of the rocker cover, attached to the breather pipe on the right hand side (see http://i68.photobucket.com/albums/i35/mex_nick/airbreather1.jpg ) there is a union of rubber pipes. there is a one way valve that comes out of the housing (see http://i68.photobucket.com/albums/i35/mex_nick/airbreather2.jpg & http://i68.photobucket.com/albums/i35/mex_nick/airbreather3.jpg ), is this supposed to happen..can it make a difference to the air mixture??

i listened to the engine whilst it was running and the noise does seem to be coming from this area. i also took off the the rubber connecter between the air intake and the throttle body (see http://i68.photobucket.com/albums/i35/mex_nick/throttlehousing.jpg ) and noticed that it was a bit cracked on the inside but there doesn't appear to be any holes..is this a problem?

one thing i did notice but i don't think it will make any impact on this fault is that the two pin electrical connector on the brake servo, below the expansion tank has corroded and one of the pins has snapped (see http://i68.photobucket.com/albums/i35/mex_nick/brakeres5.jpg & http://i68.photobucket.com/albums/i35/mex_nick/brakeres4.jpg ) what problems could this cause??
i couldn't locate that air bypass valve that alicabrio mentioned… am i being thick??

sorry for all the questions but i'm at a loss trying to find this fault..

Stefan

If you look at the image airbreather1.jpg

The auxiliary air valve opens/closes the flow of air through the steel pipe that you can see poking out from behind/under the throttle body housing - it's the 15mm (approx) dia steel pipe that's facing the camera. This bypasses the throttle body and allows more air into the engine at start up. It's gradually closed off by a bi-metallic strip that's heated by a constant 12v feed. This is hidden away underneath/behind the intake manifold.

The rubber/plastic connector you show in airbreather2 and 3 images looks very different to mine. My connecter (as far as I recall) doesn't have a valve in it - it's just a rubber connector.

The valve in there may be causing the whistling.

Ali Cabrio

PS - of course, this may mean that my car, which isn't whistling, should be whistling…. and is missing the valve that you've got.

have a look at;

http://dana.ucc.nau.edu/~kaw5/mechanical_files/enginevacuum.jpg

and

http://dana.ucc.nau.edu/~kaw5/mechanical_files/1988CISenginevacuum.jpg

One of those should help

Ali

thanks ali

have checked the air aux valve and seems to be working ok. don't know why there's a valve in my breather set up, will have to investigate that more, if i get any answers i'll post them here.

thanks for all info and advice..