Date: Thu, 10 Feb 2005 17:03:03 GMT From: hohnospamlid.invalid (Goran Larsson) Subject: Re: Engine question
In article <420B87AB.46BC3504nospamsssssssssssssssssssssssssssizefitter.com>, Johannes H Andersen <johsnospamsssssssssssssssssssssssssssizefitter.com> wrote: > What is this small air hose on the cylinder cover for? It is part of the crankcase ventilation system. > There is a round > 1/2" hole in the cover with a rubber ring. A nylon fork in the hole branches > in two directions. The small hose should connect to a small check valve and then on to the throttle housing. During low load conditions the low pressure in the throttle housing is used to evacuate gasses from the engine through this hose. The check valve will close when there is pressure in the throttle housing (when the turbo is providing pressure). The large hose should connect to the suction side of the turbo and is used to evacuate gasses from the engine when the turbo is providing pressure. This is an overview. The details vary between engine models. A working crankcase ventilation system is vital for the engine. > I sensed a whiff of petrol in the car and found that the > nylon thingy had popped out of the hole. I put it back, but it didn't fit > well as the rubber ring had become brittle; it needed replacement. A common problem. Just buy a new rubber ring. > However, after > I had replaced the rubber ring and everything was air tight, I started up > and got check engine for a short while, then the idle raced up and down > and eventually settled at the correct 900 rpm; after that no problems. > It felt like the engine adjusted itself to the new conditions - can it > really do that? Yes. You didn't tell us what engine this is, but the idle will be affected if the crankcase ventilation system is leaking. The leak will provide extra air into the throttle housing and the ECU has compensated for this by closing the idle control valve (older engines) or throttle plate (Trionic 7 engines). When you fixed the leak the ECU had to find out what to change to get the correct idle again. -- G–ran Larsson http://www.nospam.com/saab/
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