Mushroom Valve

[chris1972]

In an attempt to solve an oil leak that appears to be coming from the front of the valley gasket, behind my dizzy, I have been looking at crankcase breathing issues. I have so far cleaned the flame trap, breather pipes and T piece with petrol, so they are all now spotless. I was also going to replace the mushroom valve on the other rocker cover, so ordered a new one from Rimmer Bros, together with a new sponge filter.

Went to fit it this eve and guess what... It won't fit!!! The old mushroom valve has seen better days. It moves quite freely within the bore of the rocker cover (although the tolerances are tight). I have thoroughly cleaned the old valve and put it back in with a new sponge filter for now.

I was tempted to machine a little of the shaft off the new one, but won't bother if it isn't worth the effort. Is this valve meant to be really tight or is it meant to move slightly?

[SILICONEKID350HP]

Why is the hole so tiny ? I wonder what would happen if you drilled it out and made a larger hole ..

[Boosted LS1]

^ You would lose vacuam and end up with a less efficient pcv system.

[SILICONEKID350HP]

Boosted LS1 said:

^ You would lose vacuam and end up with a less efficient pcv system.

Would it damage the engine ?

[MADMAX2]

SILICONEKID350HP said:

Boosted LS1 said:

^ You would lose vacuam and end up with a less efficient pcv system.

Would it damage the engine ?

tell me you havnt made the hole bigger Daz

[K4TRV]

I removed mine and put in a rivet and sealant, effectively sealing the hole.................it is no more than 5 thousands of an inch in diameter, yet the Scrutineers (MSA ones), at Prescott if I left it in place, would fail it and insist upon a 1 litre catch tank & breather!!

In 3-years, I have not had an issue.......either with oil leaks, tick-over or running issues....??

Recommend that you do not open it up, but if Sprinting, remove and seal it up!!

Daz, you must have a drop of Silicon around??

Trev

[SILICONEKID350HP]

MADMAX2 said:

tell me you havnt made the hole bigger Daz

Yes I put a 2mm drill bit straight through it ..I can now actually blow through it ..Any problems .

[Boosted LS1]

You may develop an oil leak here and there but the cobra guys like that with their blingy open breather systems, lol. Doubt you'll damage anything though.

[chris1972]

So the tighter the better for the mushroom... so to speak!