Unmetered air will hurt fuel trims.

 

Are you referring to the filters on the valve covers, if so, they will not let unmetered air into the air intake. The guys are plugging the vacuum lines that evacuate the oil fumes and installing filters in its place. Basically eliminating the positive crankcase ventilation system.

 

This is the one thing about Rovers that I really struggle with. It points to just how cheap Land Rover was with so many aspects of these trucks. The engine was designed by GM in the late 50s,....and GM sold off the manufacturing rights to the Brits about 1961 if I recall. Being a GM engine,....all the fasteners were SAE,........not metric. Land Rover, in its infinite wisdom, as it converted the various fasteners over time, decided to make special SAE threaded fasteners with Metric Heads,.........Perhaps re-tooling to make the threads in the heads (and blocks?) metric threads was cost prohibitive,....but,....I cant imagine it would have been. I went through the same process,.....Off to ACE hardware, where I realized, using their thread gauge, that these wacky 12 point bolts,..were actually SAE 1/4". So, off I went to Tractor supply down the street from my home, to pick up my new valve cover and exhaust manifold bolts. That was a prior Disco,.....I made sure the new owner was aware when I sold it.

SAE Bolts with Metric heads,...............only in the UK.

 

Mine is oily on the driver side, too.

Joe, can you explain that, please? The lines I put filters on returned to the throttle body. Where they formerly returned to the throttle body, I inserted a bolt and clamped it. It keeps oil and oil vapor from gunking the throttle plate and intake tubes. Well, anyway, after I cleaned mine they seemed to stay clean.

What is the positive ventilation system? Air being pulled out of the valve covers? I'm confused.

 

The system works like this. vacuum from the intake(after the throttle plate) is stronger than vacuum before the throttle plate at say idle. This pulls crankcase fumes from one of the valve covers and the other side is hooked up before the throttle plate, which has less vacuum until the throttle is opened up. This system removes oil vapors and burns them in combustion, keeping them from just entering the atmosphere(like the older engines with just a pipe that vented). It is an emission thing that started in the late 60's.



Older engines had a down pipe that went down the back of the engine and would drip condensed oil from vapors and of course the vapors also.

 

What you guys are doing is defeating the closed PCV system and making it an open system. A no-no in some states. The reason your throttle body is clean now is because it is no longer pulling fumes from the valve cover on that side. If you put filters on both sides, then you are eliminating the whole PCV system. There will always be blow-by from the pistons and gets worse with age, and the filters that you install will with time get oil soaked and drip.
Blow-by is of course, gases that make it past the rings at combustion. The pistons themselves, as they go up and down, create pressure and vacuum inside the block with each stroke and the blow-by itself creates a pressure inside the block. If not vented it will blow gaskets, force oil past rings, valve seals etc.

 

Thanks, Joe. It sounds alot like the setup on my diesel. It only has one valve cover (5 cylinder) and the hose goes to a separator/beer can sized doohickey, then to the ground. I've never seen even a drop of oil from the end of the hose (but it has imperceptible blow by--mercedes engineering).

And it is a cousin to the EGR delete insofar as some states disapprove and an EGR utterly ruins your intake if unburnt hydrocarbons make it into your exhaust because they are sent right back to the intake.

So I have nothing to do at 5 am every morning except read the forums and not wake the rest of my family and I read this, which confirms your explanation and also confirms my general belief that if something is a no no in some states it is probably a yes yes for your engine. Oil laden air in the cylinders effectively lowers your octane and makes for dirty exhaust. What a scam.

So, basically, PCV air is filthy, unmetered air! AND it gets worse with engine/ring decrepitude. Double scam! Mod vaults to top of list coequal with hood strut!

Alex, if you read that, it MAY militate the addition of a catch/beer can to the setup, in a perfect world. More bling from your bucks.


But I personally think those funds are put to better use on a Duramax.

 

Because the lack of throttle plates, the venting system in older diesels is not applicable.

A healthy engine, at idle or low throttle application, will pull air from anywhere it can. All that air is supposed to be measured by the air mass meter. Open the sealed system and it changes fuel trims. Some systems are so sensitive that a badly leaking gasket can mess with fuel trims. Not only that, some manufactures also take engine vacuum into piston ring design and not having a vacuum on the crankcase will actually cause oil consumption to increase.

 

Oh I agree. My diesel just grabs whatever air it wants. A simple leaking o ring on our injectors can cause havoc. But the air from the valve covers is after the MAF on a rover so it is unmetered, no?

I bet this is why I smell I slight exhausty perfume from the air con when I am at a stop light.

 

Well I am reading more and getting confused. We don't have a pcv valve? It was created so tanks wouldn't suck water while fording? There is water in blow by? Backfire protection?!

Unfortunately I have to work today but hopefully some esteemed person will explain how the mod is right or wrong and why. I'll check back.