Not sure is this is good or bad but need some advice either way. Came across this issue while putting my engine back together (S4 T2). This nipple on the center iron no longer exists and has been drilled and tapped for a plug.




I think that this goes to the pcv valve as part of the crankcase ventilation system. However there must have been a reason that the builder thought it was ok to plug it up rather than put in a new nipple. I would ask the builder but they recently went out of business and I just now noticed it. Thank you for any help you can provide.

Edit: here is a picture of the plug I'm describing.

 

had a thread posted for the opposite hoping that someone might offer an easier way to close it than tapping a plug in, except for a Cosmo thin iron plate which has the hole on both sides rather only one on the FC iron

https://www.rx7club.com/20b-forum-95...plate-1166345/

but according to j9fd3s, on the FC it’s plumbed to a firewall connectiin that goes to a charcoal filter. Which suggests it’s an emission thing.



FC parts diagram showing hose/piping for intermediate iron oil sump blow-by nipple


So somebody either got rid of that or it was used on an engine in a different chassis, then it’s plugged to prevent a messy oil leak as blow-by fumes from the oil sump would come out there if left open. Which is why I needed to plug them on the Cosmo iron.

hths …
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Mine is routed to the pcv valve which is what is confusing me. Everyone says it should go to the charcoal canister but that's where my oil filter neck goes.

I just want to know if it's common to do this or if they assumed that I was going to be doing something other than my plans to keep it close to stock.

 

I might have misunderstood or gotten it wrong wrt the actual use, but the FC group should be able to guide it on it. However, the oil filler neck is the same place the hole goes to.
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I was just cleaning in the area today. That connection near the oil filler neck runs straight back towards the firewall and connects to a solid pipe connected to the firewall. It travels towards the passenger side. It stops short and is connected to a hose that leads to the charcoal canister.

If you do some research into how the canister actually works. It will provide some guidance.

 

Im really struggling to get this plug out. I actually was able to get in touch with the shop who did the work to my irons and they said that red loctite was used to secure the plug in place. I have been unable to get the appropriate amount of heat into the plug in order to remove it and have all but destroyed the hex key and will have to use an easy out to get any grip on the plug. My issue is that I reluctant to apply my propane torch directly to the plug because of how close it is to the new water seals. I have tried heating up an allen key to the point of it being glowing red and installing it to try and transfer heat to the plug. I have also used a 100watt soldering iron held in the key of the plug for 10 minutes and have so far been unable to budge the plug. I"m positive that the plug just isn't getting hot enough to weaken the loctite bond so that I can loosen the plug.

Are my concerns about damaging the water seals valid or is there enough distance (appears to be about a half inch) that the 500F necessary to break the loctite wont propagate far enough to damage the seals. Thank you for any help that anybody can provide.

 

​​​​​​Update... Got the little guy out with heat and gentle prodding.

 

That is the "fresh air" port for the PCV system. The crankcase ventilation draws air from the inside of the engine through the oil filler neck, which is generally free of oil splash. The missing port is where air comes in to the engine from. It DOES see oil splash so you really only want air to be going in, not out. Mazda routed the evaporative emissions system to it to kill two birds with one stone. Nice idea, really.

If you are running the engine in a non emissions, non PCV setup, you would want that port capped off or plugged. Maybe he missed the memo.