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Land Rover Series 2.25P breathers

Posted in Land Rover on 24 Mar 2010 at 20:50 UTC
Last modified: 08 Jan 2012 at 00:21 UTC

The Land Rover 2.25 petrol engine was produced and used for 27 years, several changes were made to the crankcase ventilation (breather) system over the years to reduce emissions and to comply with tighter regulations. The breather system fitted to an engine may vary depending on date of manufacture, country and history, this article lists the main types of breather systems used..

Basic breathers (to atmosphere)

The basic breather system simply vents any excess crankcase pressure to the atmosphere via a pair of wire mesh filters. One of these breathers is on top of the rocker cover and secured by a single bolt through the base, it has slots around the side for ventilation. The other breather also serves as the oil filler cap, it sits in the top of the filler tube and has slots around the underside. These filters should be cleaned in petrol every 5000 miles, less if used in harsh environments.

Relevent part numbers:

(See Series II/IIA or III parts catalogue)

Optional crankcase emission control kit

The crankcase emission control kit replaces the rocker cover breather with one that has a hose fitting instead of slots in the bottom and is connected to the air intake elbow. The oil filler tube is replace with one that has a hose fitting near the bottom and the cap is replaced with a twist-on sealed one. The oil filler pipe is connected to the inlet manifold via a PCV valve, this can lead to engine oil being sucked from the sump to the manifold if the PCV valve diaphragm splits.

This system seems to be included as standard on Series III engines with prefix 901/904 and suffix C-D.

Relevent part numbers:

(See Series IIA/III optional parts catalogue)

Engines with oil filler cap on the rocker cover

These (late) engines removed the oil filler tube and replaced it with a blanking plate; the only breather is the one in the rocker cover, which is connected to both the air intake elbow and the carb base adaptor using a T piece.

The "European detoxed" air intake elbow and carb base each have an extra port, I have no idea what these are for as the parts book doesn't show them connected to anything.

Relevent part numbers:

(See Series III parts catalogue)


From Nigel Stevens on 05 May 2013 at 21:23 UTC
Stumbled on one of your archives on petrol oil breathers and wondered how to access your other land rover posts.
Thanks Nigel

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