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Old 18 Aug 2005, 20:43 (Ref:1385833)   #1
Lawrence2004
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Remote oil pump - pressure excessive!! Any Ideas Why???

Hiya all,

I have a 3.5L Rover V8 engine with dry sump setup and external oil pump.

It all works but oil pressure is about 80psi at tickover and when driving it goes just off the scale at over 90psi.

This is a tad high as it should be around 50 - 60psi max, and I am worried abouit blowing oil seals.

So I have a few questions:

It it possible to over fill the dry sump resevoir which would result in pressure being too high?

Do external oil pumps have internal pressure relief valves fitted to stop them over pressuring?

Is there any way I can reduce the pressure?

There is a round plate on the back of the oil pump but I have no idea whats behind it, any one have any ideas?

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[IMG][/IMG]

Thanks for your help,

Lawrence
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Old 19 Aug 2005, 12:56 (Ref:1386323)   #2
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Quote:
Originally Posted by Lawrence2004
Hiya all,

I have a 3.5L Rover V8 engine with dry sump setup and external oil pump.

It all works but oil pressure is about 80psi at tickover and when driving it goes just off the scale at over 90psi.

This is a tad high as it should be around 50 - 60psi max, and I am worried abouit blowing oil seals.

So I have a few questions:

It it possible to over fill the dry sump resevoir which would result in pressure being too high?
It is possible to overfill the tank but this will not affect pressure. Excess oil will simply puke to the overflow tank.

Quote:
Do external oil pumps have internal pressure relief valves fitted to stop them over pressuring?
Yes, but the pressure adjuster is external, not internal. There should be a stud with a lock nut (jam nut) at the bottom of the pump section with the hose leading to where the oil line enters the block (usually at the filter boss). Lossen the jam nut and back off the stud a turn. Run the engine to see if the pressure moves towards where you want it. Repeat or reverse direction as needed.

Quote:
Is there any way I can reduce the pressure?
Yes, see above.

Quote:
There is a round plate on the back of the oil pump but I have no idea whats behind it, any one have any ideas?
This is usually a mechanical drive for a tach, alternator or external water pump. If the adjuster I refer to above is not on the bottom side of the pump, it may be behind this plate (though I doubt it). If the procedure I outline above doesn't work, send me pics of the bottom of the pump and we'll go from there.

BTW, external pumps are designed to ensure good pressure at all times and revs. Both of my dry sumped engines make 90-ish psi at startup, so I wouldn't be too concerned. Is this a race engine or a street engine? Race engines will need more pressure than street engines because 1) their internal clearances are larger, and 2) the oil tends to thin out as it heats up at high revs. In any case, don't sweat blowing a seal. If this engine was assembled with a dry sump in mind it looks normal to me.

Good luck!
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Old 19 Aug 2005, 19:33 (Ref:1386594)   #3
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Lawrence Tha looks like a Weaver pump to me, I have one of those for a car I am renovating, I also have an orginal manual here. I have scanned some pages in on another thread for Racing59 and one of the pages relate to excessivly high oil pressure. The obvius firstt route to look is the pressure release vale on the pump body and its correct adjustment but there are other possible causes.

Here is the thread if you need any other pages posted e.g setting up the pressure relief valve let me know. http://tentenths.com/forum/showthrea...0&page=5&pp=15
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Old 20 Aug 2005, 07:11 (Ref:1386805)   #4
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In the bottom image, the silver "plug" on the top of the black section of pump, I bet if you open up that, you'll find your relieve valve / spring.

Like Al, said, have a look at the info he scanned for me.

What's the pressure like when the motor is hot?

Rob.
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Old 20 Aug 2005, 11:21 (Ref:1386892)   #5
Lawrence2004
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Hiya again, thanks for your help guys, I have found a big round screw head accompanied by a lock nut on the back underneath corner of the pump, so it sounds like this is where I set the oil pressure, will investigare shortly starting there, if no luck I shall remove the plate of the back & have a peek inside.

Al, would it be possible to scan page 71 of that oil pump manual?

Thanks again

Lawrence
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Old 26 Aug 2005, 03:11 (Ref:1391471)   #6
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Lawrence...that used to happen a lot here in the States with Short Track cars that compete on Oval tracks. The pick-up can sometime be the wrong one for the "scavenger"...pulling in to much oil to quickly. I do not know how it was fixed or adjusted but Barnes and Weaver have great support people here in the USA.

Great luck to you..do not start that beautiful motor with all that pressure!!
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Old 27 Aug 2005, 00:56 (Ref:1392258)   #7
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Ok, have since fiddled with the adjuster which didnt actually make any noticeable difference.

So I removed the adjuster bolt, spring and pointy end bit and replaced the original spring with one about 12mm shorter (to lessen the pressure)

Now instead of ticking over at about 85psi its now down to 30psi.

Would you say thats acceptable? it still reaches about 85 when reved but consideing thats what it used to be on tickover its a good improvement

Thanks for all your help and advice, this is an excellent forum!

Cheers

Lawrence
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Old 27 Aug 2005, 02:01 (Ref:1392269)   #8
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Quote:
Originally Posted by Lawrence2004
I removed the adjuster bolt, spring and pointy end bit and replaced the original spring with one about 12mm shorter (to lessen the pressure)

Now instead of ticking over at about 85psi its now down to 30psi.

Would you say thats acceptable? It still reaches about 85 when reved but consideing thats what it used to be on tickover its a good improvement.
I didn't see if you answered my question about the use of the car. Is it a race car or street car? If it is a race car, be careful that you have not lowered it too far. After running a race engine for a while and getting the oil hot it is not uncommon to see idle oil pressure drop 50 psi - which could leave you with zero...
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Old 27 Aug 2005, 12:51 (Ref:1392441)   #9
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at a glance from the pics i would say race
be carefull not to let the pressure drop off to much!
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Old 27 Aug 2005, 16:24 (Ref:1392544)   #10
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Hiya, its actually a road going car, well my weekend toy & will be used for the occasional trackday )

I will keep an eye on the pressure, but the 30psi tickover pressure was with a hot engine.

So hopefully it should be ok.
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Old 27 Aug 2005, 16:29 (Ref:1392547)   #11
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Good on ya, Lawrence!

Anyway, 30 psi at idle with the oil above 90 C is just fine. Have fun!
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