Rmb Oil Pressure Relief valve

[Roger Holman]

The OPRV on the RMB engine is situated, roughly, underneath the exhaust manifold. Adjustment, hopefully, produces a result on the Oil Pressure Gauge.

I have an engine in my RMC, the rotating parts of which has been rebuilt, at considerable expence, by a very reputable company. In order to prevent me getting oil up to my armpit when doing an oil filter change, I have fitted a Flexolite conversion. Since fitting the conversion I have blown apart four spin on filter elements, depositing too much oil on he workshop floor and the road. It has been suggested, and I am perfectly content to accept this suggestion, that the oil pressure relief valve needs to be wound out 'a bit'.

I cannot remember how much I 'wound out' the OPRV when I put the engine back together.

I was hoping to find, somewhere, an indication such as; 'upon reassembly, screw the OPRV in tight, then back it off by 'X' number of turns, run the engine to operating temperature, and adjust the OPRV to obtain the prescribed 30psi at 40mph'. I have trawled the Workshop Manual, the excellent WSM suppliment produced by the Riley RM Club, S.V. Haddletons Riley Maintenance Manual, and none give any guidance on this problem.

In all my RM owning life, off and on for about 50 years, It has been suggested that a lb/mph parity is an ideal. after this rebuild I have that sort of parity and ideal, I also have a start from cold OP which will go tothe top of the gauge, and will idle, when hot, at about 20 psi.

It seems that the adjustment of the OPRV might be a matter of 'hit and miss', which I am reluctant to accept having spent several thousand pounds on a rebuilt engine.

Does anyone have a 'rule of thumb' setting for the OPRV for an RMB engine? I last deposited the contents of my sump on the road on Friday (27.03.2020) and have just fitted canister No.5. Canisters 1 - 4 were all MANN, the latest one is MAHLE, which feels a tad heavier and more solid.

I realy would appreciate some guidance, if anyone has any suggestions, they will be gratefully pored over and considered.

Thanks.

[sprite124]

Have you checked that the spin off element filter is of the type that incorporates a bypass, so that when the oil cold and thick, the oil is made to bypass the filter and pass straight through. Only when the oil gets up to temperature does it go via the the filter element.

[Roger Holman]

Hello, and thanks for answering.

In the course of this sorry tale I have disected 5 different spin on canisters, and they all have included a by-pass valve, in spite of my specification to the suppliers that a by-pass valve is not required because there already is a by-pass valve incorporated in the Tecalamit filter head.

After canister No. 6 blew out I have retired hurt, and removed the Flexolite Conversion and refitted the original Tecalamit centre bolt filter. Normal running has been resumed whilst I lick my wounds and save up enough money to buy another tanker full of engine oil.

Roger.