Bypass Oil Filter Question

[Batavia]

I have just be refurbishing the oil filter vessel on one of my Bolinder 1052s and discovered that the orifice through which the oil has to pass after it has been through the element is less than 1 mm diameter - it took a while to even find the hole, as it is deep down inside the vessel).

 

I then opened up a seemingly identical vessel on another 1052 and on this, the hole is about 5 mm dia. Given its position, it is very unlikely that a smaller hole has been drilled out on this one

 

The vessel is unbranded but takes a Mann PF1155 element. The flow is from the discharge of the oil pump, through the filter and back into the sump

 

I wonder whether:

 

(a) they initially started with a small hole, and found that hardly any oil went through the filter;

or:

( b ) they started with a large hole, and found there was hardly any oil pressure, due to all the oil going through the filter.

Any thoughts as to the size of hole that more commonly be encountered with a bypass filter on a similar engine?

 

Bemused of Berkhamsted

Edited April 7, 2016 by Batavia

[Tiggs]

I thought all of the oil went through the filer anyway - does it not? Surely it should other wise any debris in it can block a passageway.

 

I thought the pressure reading was due to the pump raising the pressure of the oil and the flow being restricted by the oil paths though the engine to the bearings and such. is it not like this on a Bolinder?

 

The flow though a 5mm hole is about 30 x that though a 1mm hole so it's a surprising difference.

Edited April 7, 2016 by Tiggs

[Batavia]

In a bypass filter, as opposed to a full flow filter (which is normal for most modern engines) only a certain proportion of the oil goes through the filter - but as you say, there is a large difference in flow rate between the two vessels I have.

 

Chris G