Rocker cover air pressure

Perhaps someone can give the benefit of their technical knowledge, I
have recently discovered air being pushed out of the gasket under the
rocker cover on my 110 2.5D. I have ordered a new gasket to replace the
old grotty one, but a number of people I have mentioned this to have
expressed surprise that I have air pressure inside the rocker cover at
all. I have tried removing the breather tube from the oil filer cap,
and sure enough there is air being pumped out of the filler cap as the
engine idles. This seems strange given that there is a filter inside
the cap which would indicate to me that air is supposed to flow into
the rocker cover not out. Frightening phrases such as 'crank case over
pressure' and 'piston replacement' have also been mentioned, so my
questions are:

Should air be blown out of the rocker cover or sucked in?

If it should be sucked in why is mine being blown out and how do I fix
this?

In trepidation...

Smudge

Smudge wrote:

> Should air be blown out of the rocker cover or sucked in?

Blown out - any compression that travels past the piston rings has to go
somewhere, hence having a breather on the rocker cover.
>
> If it should be sucked in why is mine being blown out and how do I fix
> this?

If you are suffering from excessive pressure it's a fair sign that
pistons/rings are worn and the engine is on it's way out. And lets face
it the old 2.5D wasn't the most long lived engine on earth so it's
distinctly possible that yours is worn out.


--
EMB

On 22 Nov 2005 13:00:39 -0800, "Smudge"
<[email protected]> wrote:

>Should air be blown out of the rocker cover or sucked in?

Definately should be blowing out. The more it blows the more knackered
the engine is.
When it starts blowing oil out past the gasket and popping the cap off
regularily start considering the rebuild!

Even after being rebuilt, my engine still feels like its blowing quite
a bit - but its an awful lot less than it used to and its now easily
oil tight.

Breather pipes can block up. I'm not conversant with this engine or its
idiosyncrasies, so I don't know where it leads the crankcase pressure, but I
do suggest you check the breather system for blockages.

Tony

"Smudge" <[email protected]> wrote in message
news:[email protected]...
> Perhaps someone can give the benefit of their technical knowledge, I
> have recently discovered air being pushed out of the gasket under the
> rocker cover on my 110 2.5D. I have ordered a new gasket to replace the
> old grotty one, but a number of people I have mentioned this to have
> expressed surprise that I have air pressure inside the rocker cover at
> all. I have tried removing the breather tube from the oil filer cap,
> and sure enough there is air being pumped out of the filler cap as the
> engine idles. This seems strange given that there is a filter inside
> the cap which would indicate to me that air is supposed to flow into
> the rocker cover not out. Frightening phrases such as 'crank case over
> pressure' and 'piston replacement' have also been mentioned, so my
> questions are:
>
> Should air be blown out of the rocker cover or sucked in?
>
> If it should be sucked in why is mine being blown out and how do I fix
> this?
>
> In trepidation...
>
> Smudge
>

Smudge wrote:
>
> Should air be blown out of the rocker cover or sucked in?
>
> If it should be sucked in why is mine being blown out and how do I fix
> this?
>
> In trepidation...
>

Trepidate not my friend. It should blow out. All of these engines will blow
and will regularly wear the rubber ring-seal on the filler cap so that it
leaks like a sieve.There should be a pipe leading from the cap to the air
inlet manifold or piping which sucks all the fumes into the engine to be
consumed by hellfire.
A new three-ringed cap seal thing has been needed on mine every
couple of years for the last twenty. It lasts about as long as the
accelerator pedal cable, which is also needed every couple of years.
Don't even consider an overhaul based on a bit of hot air.

Huw

On Wed, 23 Nov 2005 20:53:58 -0000, "Huw"
<hedydd[nospam]@tiscali.co.uk> wrote:

> It lasts about as long as the
>accelerator pedal cable, which is also needed every couple of years.
>Don't even consider an overhaul based on a bit of hot air.

My 2a (with a 2.5n/aD) has an accelerator linkage that looks like it
may be made out of a bit of heavy duty coathanger metal. Its never
broken!

Many thanks for all your wisdom, I can now change my gasket and sleep
easier! Next job, a new heater to fit...


Smudge

Tom Woods wrote:
> On Wed, 23 Nov 2005 20:53:58 -0000, "Huw"
> <hedydd[nospam]@tiscali.co.uk> wrote:
>
>> It lasts about as long as the
>> accelerator pedal cable, which is also needed every couple of years.
>> Don't even consider an overhaul based on a bit of hot air.
>
> My 2a (with a 2.5n/aD) has an accelerator linkage that looks like it
> may be made out of a bit of heavy duty coathanger metal. Its never
> broken!

The difference between men and boys is how hard they work their toys.

Huw