JP2 oil pressure

[monkeyhanger]

  My JP's oil pressure gauge reads 18lbs when warm and underway. I've got the water pump off at the moment, so access to my oil pump is easy. Is it worth turning the adjusting screw a bit to get the pressure up to 20lb? If so, do I screw it in or out, and by how much.? I should mention that the big end shells were replaced 3 years ago, and the main bearings 2 years before that.

[frangar]

25 minutes ago, monkeyhanger said:

  My JP's oil pressure gauge reads 18lbs when warm and underway. I've got the water pump off at the moment, so access to my oil pump is easy. Is it worth turning the adjusting screw a bit to get the pressure up to 20lb? If so, do I screw it in or out, and by how much.? I should mention that the big end shells were replaced 3 years ago, and the main bearings 2 years before that.

Why go higher?? I’d say that was bang on…what oil grade are you running at? The manual says 15-20psi when running so 18psi is good. What’s it doing at idle when warm?  If it’s below 15psi then possibly it needs thinking about but even then I wouldn’t worry unless it’s below 10 psi. It’s very different tolerances to a modem engine. 

[monkeyhanger]

17 hours ago, frangar said:

Why go higher?? I’d say that was bang on…what oil grade are you running at? The manual says 15-20psi when running so 18psi is good. What’s it doing at idle when warm?  If it’s below 15psi then possibly it needs thinking about but even then I wouldn’t worry unless it’s below 10 psi. It’s very different tolerances to a modem engine. 

I run it on Halfords 20-50, as I have converted it to wet sump and have an oil filter  fitted.When the engine is really hot the pressure is probably around 10lb

[Tracy D'arth]

18 hours ago, monkeyhanger said:

  My JP's oil pressure gauge reads 18lbs when warm and underway. I've got the water pump off at the moment, so access to my oil pump is easy. Is it worth turning the adjusting screw a bit to get the pressure up to 20lb? If so, do I screw it in or out, and by how much.? I should mention that the big end shells were replaced 3 years ago, and the main bearings 2 years before that.

When the JPs run without any pump, just splash lubed, they ran just fine. Why worry?

[frangar]

1 hour ago, monkeyhanger said:

I run it on Halfords 20-50, as I have converted it to wet sump and have an oil filter  fitted.When the engine is really hot the pressure is probably around 10lb

Adjusting the pump might mask other issues tho such as worn mains. Personally I’d steer clear of multigrades…I now run mine on straight 30. It’s harder to start in winter but even on hot summer days I get 15 psi on tick over and 18 running when it’s well up to operating temperature. 
 

I’m not sure about an oil filter as most modern filters are probably designed with much higher pressures in mind. 

57 minutes ago, Tracy D'arth said:

When the JPs run without any pump, just splash lubed, they ran just fine. Why worry?

I’ve never seen a JP without an oil pump. They need a bit of pressure to move the oil round. They aren’t designed for splash lube. 

[Tracy D'arth]

Lister JP3, no oil pump. JP2 is a bit different, not much.

[frangar]

5 minutes ago, Tracy D'arth said:

Lister JP3, no oil pump. JP2 is a bit different, not much.

Well I’ve never seen any JP without a pump…are you not thinking of the top end lube?? That’s not pumped on a JP but is on a JK. The mains are pumped on all. My parts books agree with me! 

[BWM]

4 hours ago, Tracy D'arth said:

Lister JP3, no oil pump. JP2 is a bit different, not much.

They all have a pump that draws from the 'vee' at the bottom of the sump via a strainer.

[BEngo]

On 13/01/2023 at 17:13, monkeyhanger said:

  My JP's oil pressure gauge reads 18lbs when warm and underway. I've got the water pump off at the moment, so access to my oil pump is easy. Is it worth turning the adjusting screw a bit to get the pressure up to 20lb? If so, do I screw it in or out, and by how much.? I should mention that the big end shells were replaced 3 years ago, and the main bearings 2 years before that.

Rule 1:  If it ain't  broke, don't ffix it.

 

Rule 2 : If it is running OK, apply Rule 1.

 

The principal purpose of oil flow is not to lubricate the bearings. That can (at JP speeds and bearing  loads) be done adequately by splash.  Oil flow is there to take away the heat generated by the bearing.  The difference in flow rate at any particular well-fitted bearing between 18 and 20 psi is going to be small, gusting  minute.

 

If the bearings are slack, through wear, then all bets are off, but adjusting the oil pressure relief setting will neither help nor tackle the root cause.

N