S III 2.25 1976 Anti-pollution gear

[C00P]

Hi folks,

As I understand it, the only anti-pollution gear that my machine sports is PCV (tube from the carby around the front of the engine to the oil filler pipe) and a fuel tank vapour trap (Carbon Cannister with a feed to the air intake).I think this also includes what I assume to be a fuel overflow tank tucked in under the rear mudguard.
There is also a small pipe from the top of the tappet cover which also feeds into the carbie (I think). I assume this is part of the PCV.
A mate claims significantly improved fuel consumption by defeating these systems. Does anyone here now if this is true? What effect would blocking these systems have (apart from increasing emissions. I assume).

Coop

[crackers]

I'm no expert but my understanding is that these two anti-pollution systems are the only ones that do NOT hurt your fuel economy or power.

[JDNSW]

The PCV system consists of a pipe from the oil filler to the PCV valve next to the carburettor, with a rubber elbow from there to the adapter below the carburettor, and a hose from the top of the rocker cover vent to the elbow in the air intake above the carburettor.

Unless the valve is faulty (stuck or split diaphragm) removing this will have no effect whatever on performance, but unless complete crankcase ventilation is changed to a proper open crankcase ventilation system, the engine is likely to be damaged by sludge buildup, depending on use and climate.

The fuel tank vapour trap will also make no difference to performance unless it is blocked. Removing it will make no difference except to render the vehicle technically unroadworthy, provided fuel tank ventilation is still provided.

John

[C00P]

Thanks John, That's what I thought was the case. I suspect my mate is thinking of other systems such as the throttle valve opening system (on over-run)which was installed on some vehicles at around this time, which probably do have a slight impact on fuel consumption.

Coop

[vnx205]

He may have been thinking of something else.

He may have done at the same time some other adjustments or maintenance that really did affect fuel consumption.

He may just be one of those people who is able to convince themselves that the vehicle goes faster just because they:

Blackened the tyres
Cleaned the windscreen
Painted the vehicle red
Fitted a Hiclone

:)

Given the simplicity of the Series III emissions fittings, it's hard to imagine anyone thinking they would make a big difference.

[JDNSW]

Yes. I'm not sure what was on later Series 3, but I think they included a fuel shutoff on overrun, different distributor, and sealed mixture and idling control screws. These did affect consumption, driveability and power, but are not all that easy to disconnect.

John

[C00P]

My workshop manual also describes an air pump, although I've never seen one fitted. Were they used in Australia?

Coop

[JDNSW]

They were used on the V8, although I am not sure that applied to the Series 3/110 in Australia, maybe only the Rangerover due to the detuning of the S3 and perhaps different vehicle classification.

John

[JDNSW]

........

Given the simplicity of the Series III emissions fittings, it's hard to imagine anyone thinking they would make a big difference.

The PCV in particular has the potential to result in poor running, but only if faulty. I've had this myself - split diaphragm, but any vacuum leak could do it. Of course, the solution is to fix it not remove it, especially for this, as it improves engine life by providing good crankcase ventilation without letting in dust.

John

[C00P]

Have just finished replacing all the little rubber connections on the PCV system. What on earth possessed Land Rover to join a large pipe (the outlet from the PCV valve) onto a smaller tube (the metal line that runs around to the oil inlet)? The result is that if you can't get the special rubber fitting (and you can't) you have to struggle to force a smaller diameter hose over the larger pipe. Managed this by heating it in boiling water, but it was difficult, and could have been so much easier if the tubes had been the same diameter....
As for the executive puzzle presented by the positioning of the metal line.... 'nuff said or I'll get into trouble for swearing. :censored:

Coop

[Lotz-A-Landies]

You do need to keep the PCV system operating otherwise (as John says) you will over pressurise the crankcase and you'll find leaks in other places as the oil is pushed out under pressure.

Yes the air pumps were used in Oz, they were in VW terminology a "defeat device", all they did was pump air into the exhaust so that the gasses at the other end were more dilute. The pumps also robbed power from the engine.

Not sure about the 4 cyl but the pollution controlled 6 cyl had a fixed main jet, while the pre-pollution had an adjustable main jet.

[Aussie Bob]

I hear you COOP. I solved the dilemma by getting a bend of pipe that measured the larger diameter, then sleeved the inside with some plastic pipe to get it snug on the smaller diameter.

I believe the radiator hoses are the same, the diameter of the radiator outlets are different from the diameter of the engine outlets.

All very strange engineering :confused:

[JDNSW]

I hear you COOP. I solved the dilemma by getting a bend of pipe that measured the larger diameter, then sleeved the inside with some plastic pipe to get it snug on the smaller diameter.

I believe the radiator hoses are the same, the diameter of the radiator outlets are different from the diameter of the engine outlets.

All very strange engineering :confused:
Not really - in my experience, matching pipes of different diameters using a specially moulded hose is commonplace, not just Landrover. In this case I assume that the PCV valve was an off the shelf item, and the size of the pipe was chosen as being the most appropriate bearing in mind the need to fit it round the front and still be able to remove the rocker cover without removing the pipe. And putting the different end on the pipe or getting a non-standard valve fitting made would have been a lot more expensive than specifying an adapter hose.

Similar thinking to that which sees many cars using almost flat glass instead of flat glass which could be cut to size by any glass supplier, or lights that could just as easily have been a standard type.

John