kevine Posted April 10 Report Share Posted April 10 Hello I have a Alloy polished type rocker cover with cap. I have noticed that oil seems to be misting oil through the vent hole and gather at one end as my garage is on a slope. Not really a problem but frustrating. Does the cap have to be vented, or has anybody got a solution to stop this happening. Thanks Kevin Quote Link to post Share on other sites
c.hydes Posted April 10 Report Share Posted April 10 1 minute ago, kevine said: Hello I have a Alloy polished type rocker cover with cap. I have noticed that oil seems to be misting oil through the vent hole and gather at one end as my garage is on a slope. Not really a problem but frustrating. Does the cap have to be vented, or has anybody got a solution to stop this happening. Thanks Kevin Likewise Kevin, never understood when the the inside is vented to via the large breather pipe to the plenum. Looking forward to the experts to come along and explain. Colin. Quote Link to post Share on other sites
CK's TR6 Posted April 10 Report Share Posted April 10 I fabricated a piece of light gauge aluminum sheet that fit on top of two of the rocker cover hold down studs. It had a slight bend in it upwards to spring it against the cover. That provided a gap on each end for ventilation. Stopped the mist, weeping completely. Downside is I have to shove a flat blade screwdriver against it to add oil. Quote Link to post Share on other sites
DRD Posted April 10 Report Share Posted April 10 The hole is there to allow fresh air into the rocker cover and then it gets sucked out the pipe on the side into the intake manifold. If an oil mist is being emitted from the filler cap then there must be a blockage in the ventilation system, possibly the flame trap is clogged up with gunk. Quote Link to post Share on other sites
CK's TR6 Posted April 11 Report Share Posted April 11 Flame trap? on an alloy cover? Quote Link to post Share on other sites
Mike C Posted April 11 Report Share Posted April 11 41 minutes ago, CK's TR6 said: Flame trap? on an alloy cover? It's usually in the vent line connected to the side of the cover( looks like the PCV fitted to later cars) and can block. Quote Link to post Share on other sites
CK's TR6 Posted April 11 Report Share Posted April 11 Ah, my configuration is alloy cover, fairly large hose to air/oil separator, which has a PCV to an intake common plenum. Separator drains to the sump. Even so, without the plate, I still got oil coming out of the cap. The plate stopped that. Regardless, assuming the pressure inside the rocker cover is the same as the crankcase, you would need a lower absolute pressure in the intake at sufficient flow to overcome the total blow by such an amount that ambient pressure is higher than the resultant crankcase pressure to insure flow is into the engine from that breather hole. At wide open throttle, I don’t see that occurring unless your intake is throttling the engine some. Quote Link to post Share on other sites
Mike C Posted April 11 Report Share Posted April 11 (edited) If the "PCV" has just wire gauze in it its a flame trap. It's the gauze that needs periodic cleaning. Edited April 11 by Mike C Quote Link to post Share on other sites
kevinfryer Posted April 11 Report Share Posted April 11 Thanks for the response to date. When cleaning the flame trap would you use Petrol or Break Cleaner Quote Link to post Share on other sites
stuart Posted April 11 Report Share Posted April 11 16 minutes ago, kevinfryer said: Thanks for the response to date. When cleaning the flame trap would you use Petrol or Break Cleaner They are a service item change it when you change your oil. Stuart. Quote Link to post Share on other sites
michaelfinnis Posted April 11 Report Share Posted April 11 2 hours ago, stuart said: They are a service item change it when you change your oil. Stuart. Seems a bit excessive to change every service. Workshop manual says clean with petrol. Mike Quote Link to post Share on other sites
stuart Posted April 11 Report Share Posted April 11 2 hours ago, michaelfinnis said: Seems a bit excessive to change every service. Workshop manual says clean with petrol. Mike Well they arent expensive then you know theyre clean. Most havent been touched for years and are clogged right up. Stuart. Quote Link to post Share on other sites
Mike C Posted April 11 Report Share Posted April 11 8 hours ago, michaelfinnis said: Seems a bit excessive to change every service. Workshop manual says clean with petrol. Mike I use petrol or kero to remove the gunk and then blow it clear with compressed air. There's not a huge volume of air flowing through the trap. Quote Link to post Share on other sites
kevinfryer Posted April 12 Report Share Posted April 12 I think Flame trap and new hoses are the way to go for now. Thanks for comments. Kevin Quote Link to post Share on other sites
Spit_2.5PI Posted April 12 Report Share Posted April 12 Kevin, unlike carb cars, there's little or no vacuum on the crank case breather as it connects to the plenum. I suspect Triumph didn't connect it downstream of the butterflies as perhaps they were worried about upsetting the metering unit vacuum. In any case, my flame trap was clear so I ended up putting a tiny little self-tapper through the hole. See the thread "Source for Alloy Rocker Cap that DOES Seal Properly". Cheers, Richard Quote Link to post Share on other sites
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