Crankcase ventilation.

[A900ss]

My car has been smoking on overrun recently and as I had the top end reworked last year, I hoped it wasn't valves.

I've checked the mushroom vent and it was completely blocked and letting no air in. I guess this has caused increased pressure and the wire trap in the breather on the other rocker cover was very oily and when I removed the vent pipe to the plenum, a bit of oil came out of the pipe.

A new mushroom is on order, the wire in the breather is soaking in petrol to clean it up and I have fitted new breather pipes as they are very cheap.

However, will the oil in the plenum make its way out via normal combustion or is it necessary to take the plenum off to clean the oil out?

Thanks.

[TVR Beaver]

leave it, it will find its way out eventually.... Let's hope it cures your problem?.. do you think a 1mm hole will make a lot of difference?.. maybe it will ... how blocked was the main vent.. I think this will be more the issue?

[spend]

Check your crankcase still has a good seal before re-fitting everything, just finger over the mushroom & blow down the flame trap ~ your cheeks should strain ( & then pass wind ).

If the mushroom was blocked, and you've sucked oil into the plenum air must have been entering from somewhere so the manifold vacuum could pull the oil+air through?

[jojackson4]

Make sure all the pipe spouts on the plenom are clear
Blow down every thing before you plug back together

[A900ss]

spend said:

Check your crankcase still has a good seal before re-fitting everything, just finger over the mushroom & blow down the flame trap ~ your cheeks should strain ( & then pass wind ).

I blew as hard as my lungs would allow but my lung capacity gave up before filling all the air holes in the engine!!!!
However when I let my mouth from the pipe, all my breath that I put into the pipe blew back out at me. I suggest that this indicates that my breath did put it all under pressure and that all is good.

Whilst I've being doing this I've noticed that my vacuum advance on the dizzy has seized and the vacuum pipe from the fuel regulator stinks of fuel.

Two more little jobs then.....

PS - if I try to start the car without the fuel pump powered I assume this will depressure the fuel rail enough for me to get th regulator off with minimal petrol spillage.

[TVR Beaver]

so is the mushroom still blocked?.. or is it acting like a one way valve?

just use the valve on the fuel rail to drop the pressure....

[A900ss]

New mushroom fitted but I held my finger over it to stop air escaping whilst I was blowing.

Will fuel come out of the schrader valve on the fuel rail when you let pressure out?

[TVR Beaver]

yes.... so take care ... but should not be much.....

[spend]

A900ss said:

PS - if I try to start the car without the fuel pump powered I assume this will depressure the fuel rail enough for me to get th regulator off with minimal petrol spillage.

Yes normally pulling the Fuel pump fuse/relay and letting it run out of fuel is a quick way to de-pressurize the fuel rail.

[A900ss]

Final question (for now )

I haven't taken the plenum off before but it looks like it will come off with the throttle linkage still attached. Is that right? I'll need it off to get the space for the regulator.

Thanks.

Karl.

[A900ss]

spend said:

A900ss said:

PS - if I try to start the car without the fuel pump powered I assume this will depressure the fuel rail enough for me to get th regulator off with minimal petrol spillage.

Yes normally pulling the Fuel pump fuse/relay and letting it run out of fuel is a quick way to de-pressurize the fuel rail.

I had hoped I could just try and turn the car over on the key with the immobiliser on hence no power to fuel pump.

[TVR Beaver]

yes.. will come off with linkage... just put it on the drivers side inner wing on it's back

[A900ss]

TVR Beaver said:

yes.. will come off with linkage... just put it on the drivers side inner wing on it's back

Thanks