The MGB oil filter is mounted externally on the right-hand side of the engine and changed in design several times during production. Identifying which filter type is fitted is important when ordering replacement elements or considering a conversion to the more convenient modern spin-on type. The earliest MGBs used a hanging-type oil filter cannister, mounted below the oil filter housing. This was replaced during production by an upright-type cannister of similar construction.
In October 1973, an alternative cartridge-type spin-on oil filter was introduced, though the original cannister type appears to have been reinstated around early 1974 on some engines. The cannister-type filter uses a replaceable paper element housed within a reusable metal body, secured by a centre bolt with a spring, washers, and a pressure plate. The sealing rings between the cannister and the filter housing adaptor must be renewed each time the filter is serviced to prevent oil leaks.
Spin-On Conversion
A spin-on conversion kit is available for cars originally fitted with the cannister-type filter. This converts the filter housing to accept a modern disposable spin-on cannister of the type familiar from virtually all modern cars. The conversion eliminates the mess associated with disassembling the original cannister to change the paper element, and, if fitted in place of an upright-type filter, allows the use of a non-return valve within the disposable cannister. This non-return valve prevents oil from draining out of the filter when the engine is not running, which would otherwise leave the engine momentarily under-lubricated upon start-up.
The spin-on conversion is a simple bolt-on modification that can be easily reversed by removing the conversion and refitting the original cannister for concours judging. Paper filter elements are available for the original cannister-type filters, and disposable spin-on cannisters are available for cars that have been converted or were originally fitted with the spin-on type. The sump drain plug and its sealing washer should be inspected at every oil change. A damaged or corroded drain plug thread can result in a slow oil leak or, in the worst case, sudden oil loss.
An alternative drain tap is available for owners who prefer a more convenient means of draining the sump without tools, particularly useful for regular oil changes carried out at home. When servicing the oil filter, it is good practice to check the condition of the oil cooler hoses and connections at the same time, as oil leaks in this area often coincide with filter service. On cars fitted with an oil cooler, the filter housing adaptor unions and their sealing washers should be inspected for weeping. On cars without an oil cooler, the bypass pipe between the filter housing and the cylinder block should be checked for security.
The MGOC Spares range covers paper filter elements, spin-on conversion kits, disposable spin-on cannisters, centre bolts, springs, washers, pressure plates, sealing rings, drain plugs, drain taps, and all associated oil filtering components for every MGB engine type.