Thread: By Pass Oil Filter

Originally Posted by roboyobo

Hi,

has anyone out there fitted a by pass oil filter to a 4BD1 (not a turbo)?
If so, what make and have you had any issues with it.

Thanks in advance.

The truck setup runs a dual (full flow + bypass) filter setup. I just bought one to fit to mine (see the budget turbo install thread below). Rijidij has posted the adaptor needed to fit it.

By way of explanation for others, the bypass filter is used to remove smaller particles from the lubricating oil than the main filter can deal with. I.e. the bypass filter is much finer.

The bypass filter processes a smaller flow of oil than the main filter. Ideally none or little oil will be diverted to the bypass at start-up, until the oil pressure is built up.

It should be possible to fit a remote bypass filter to the 4BD1 used in Land Rovers.

The diagram in my manual shows that the bypass filter tees into the pressure line between the pump and the main filter. After the oil passes through the bypass filter, it returns to the sump via a 1.2mm diameter orifice. The purpose of the orifice is to restrict the volumetric flow of oil (it will restrict more when the oil is cold (more viscous).

A common method to make an orifice is to tap a thread inside the bore of a fitting for the oil line. Then use an orifice plug that screws into the fitting - buy from a hydraulic shop or you can drill the plug yourself. Another way is braze up the bore of the fitting and drill the orifice through the bronze.

I have a Mann Hummel centrifugal bypass filter for my 4BD1-T. This is similar to the one used on the Land Rover TD5 engine (except mine is cleanable and the TD5 need the dirt collector replaced when it fills). This tees in like described above, but uses a relief valve to ensure that 100% of the oil goes through the main oil filter until the relief valve opens.

John, did you buy the centrifuge new or is it from a vehicle (if so which one?).

EDIT, this is the standard truck setup. The larger diameter filter is the bypass element.

Originally Posted by isuzurover

John, did you buy the centrifuge new or is it from a vehicle (if so which one?).

...

I bought it new FM025. It has a 1/4" BSP inlet port and a large bore, 4 bolt flange outlet underneath that also serves to mount the unit.

Edit: It was ($$$ ), but the upside is that it should remove smaller particles from the oil than the stock bypass element. Cleaner oil can allow extended oil changes, and no more bypass elements to replace, should offset the cost over the time I hope to have this vehicle.