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K-Series - Oil pressure relief valve


SLR No.77

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I currently have rock - solid oil pressure (as the revs climb obviously), but it never goes over 3.25 bar. I've a new engine in 1000 miles ago, and I've changed the oil pump, therefore I know there's no fault with the sender or guage. I've narrowed the problem down to the pressure release spring, but is it a case of fit another and see what happens, or is there a way of kn owingly making a change to improve the pressure? The Rover build manual gives a free length for the spring - I assume that if the spring is that length I will achieve the 4 bar I'm looking for?

Anybody any experience on this one?

 

Stu.

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The relief system is designed to operate at 4bar ish , so it should bleed off pressure above this .

Ifound after building my year 2000 engine , the pressures were high - about 6 bar hot , I found that the spring was fine in length but the plunger itself was sticking a little in the housing . A gentle rub with some paper and a new spring just in case ( only pennies ) brought everything back to 4 bar .

 

Dave

 

 

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Like Dave says, its a good plan to make sure the relief valve is functioning correctly, it could be sticking open or leaking. You could also shim the spring a little to raise the blow-off point , and old trick that has served me well in the past.

 

Oily

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Its integral with the pump, a large hex headed plunger on the left hand side of the pump inclined upwards at about 45% to the centre line of the pump, the plunger should just be visible from the top left hand side of the engine immediately below the cast in aluminium belt shroud of the pump.

 

Oily

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Ok, I have the spring out of a spare pump, and its over 42mm long!!! Build manual reckons 38.9mm for the free length. Dave - I assume I would shim it using a small washer within the screw head?

 

Next job is pop the spring out of the pump fitted to the engine, and with a little luck it will be shorter than the spare I have! I'm going to attempt it without dropping the oil, but with the front of the car jacked up *confused*. I let you know if oil pi$$es out everywhere *thumbdown* LOL.

 

Stu.

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The oil shouldnt piss out ( unless you have the engine running *wink*) .

 

I dont have the manual in front of me , but isnt the 38.9mm length - the minimum as I recall , other wise the plunger wont expose the bypass hole ....?? .

In shimming it you are increasing the length over and above 38.9mm and hence a greater pressure .

 

So your 42mm long spring is fine .

 

dave

 

 

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