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.
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:
- 247631 - Rocker cover breather
- 546440 - Oil filler/breather cap
- 90510730 - Oil filler tube
(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 modified to have 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:
- 600493 - Complete kit (Series IIA 2.25 petrol, to engine suffix H)
- 601793 - Complete kit (Series IIA 2.25 petrol, engine suffix J onwards)
- 608385 - Complete kit (Series III 2.25 petrol, engine prefix 901/904, suffix A/B)
- 512897 - Air intake elbow for II/IIA engines to suffix H (Solex carb?)
- 554414 - Air intake elbow for engines suffix J onwards
- 546277 - Rocker cover breather
- 546592 - Oil filler tube with breather port
- 542410 - PCV valve
(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:
- ERC2876 - Air intake elbow
- ERC6573 - Air intake elbow (European detoxed)
- ERC2867 - Rocker cover breather
- ERC2869 - Oil filler blanking plate
- ERC2974 - Carb base adaptor kit
- ERC6081 - Carb base adaptor kit (European detoxed)
(See Series III parts catalogue)
