Vixen Oil Pressure

[Ren32]

Hi all,

I think I have an oil pressure problem on my car (curently under debate in Engines forum) but can anybody here suggest an approx figure, as a guideline, that I should be expecting on the gauge when the engine is hot??

Engine is a newly built 1600 crossflow.

Darren.

[heightswitch]

Firstly is your guage accurate?? Seen many that give spurious readings.

also if newly re-built have you primed your oil pump etc. Is the pump a std one or new and is it a high pressure or std pressure?

Min acceptable at 700rpm is 8.5 lbf/in2 oil at 80 degrees
Min acceptable at 2000rpm is 21 lbf/in2 oil at 80 degrees

warning light will light up at 6 lbf / in2

Excess pressure when relief valve opens is 35 -40 lbf / in2

The crossy is not a high pressure engine.

Neil.

Edited by heightswitch on Monday 11th December 16:28

[tvrski]

i wouldn't trust your meter completely, i had a leaking one and after i replaced it, my pressure reading was lower. can't remember the values but as long as you've got some pressure, it should be good imo, almost no pressure isn't good but high pressure neither

i'm to slow in typing, especially english

Edited by tvrski on Monday 11th December 16:32

[Ren32]

heightswitch said:

Firstly is your guage accurate?? Seen many that give spurious readings.

also if newly re-built have you primed your oil pump etc. Is the pump a std one or new and is it a high pressure or std pressure?

Min acceptable at 700rpm is 8.5 lbf/in2 oil at 80 degrees
Min acceptable at 2000rpm is 21 lbf/in2 oil at 80 degrees

warning light will light up at 6 lbf / in2

Excess pressure when relief valve opens is 35 -40 lbf / in2

The crossy is not a high pressure engine.

Neil.

Hi Neil,

Got about 60lb on the gauge (high pressure pump) when cold at idle.
Got about 10lb on the gauge when hot at idle which will raise to 20lb max when revved?
The Gauge is an unknown quantity I'm afraid.

I'll rig up a pressure switch/lamp to eliminate a gauge fault.

Thanks for the advice.

Darren.

[heightswitch]

To fluctuate so wildly I would assume that your gauge is up the swanny. Or your oil pressure relief valve is knackered. This is in the pump itself and is a plunger and spring. It could be that this is sticky in operation.

Is your oil pump brand new and of known quality?

I would expect to see about 40 psi on a performance engine when warm at about 3500 rpm with a HP pump Previous figures were for a std pump / std engine

Neil.

[Ren32]

The pump is brand new from Burtons.

Last week when I started looking into it, I had 40lB cold at idle and about 8lB hot at idle, raising to about 12lB max when revved.

My first thought was to bleed the capillary tube, which I did with no change. Second thought was to change the pump (as the one I was using was of unknown origin). So I ordered a HP pump from Burtons. Hence figures are now slightly up but still varying massively between hot and cold.

I think I have another gauge kicking about somewhere, I better get looking for it!

[heightswitch]

Drop your sump and check the pick up pipe and unions. Take the cover of the oil pump and check the end float Fill your oil filter with oil before screwing it on. Other than that are you sure that your bearing oversizes have been measured correctly or have you not touched the bottom end?

Neil.

Edited by heightswitch on Monday 11th December 21:17

[thegamekeeper]

the oil pump does not produce the oil pressure, it just pumps oil. High pressure pumps just have a device (usually spacer or higher strength spring to control the oil pressure relief)) the pressure is generated by the space between the crank and the bearings, hence the loss of oil pressure as the bearings wear out.

[Tom Ewart]

Ren32 said:

The pump is brand new from Burtons.

Last week when I started looking into it, I had 40lB cold at idle and about 8lB hot at idle, raising to about 12lB max when revved.

My first thought was to bleed the capillary tube, which I did with no change. Second thought was to change the pump (as the one I was using was of unknown origin). So I ordered a HP pump from Burtons. Hence figures are now slightly up but still varying massively between hot and cold.

I think I have another gauge kicking about somewhere, I better get looking for it!

The new oil pump has probably given you "slightly higher" readings just because it is new and not worn at all. I don't profess to be an oil expert (but have built several x/flow engines) but it sounds to me like an issue with the clearances on the bearings. You can either plastigauge them to check them or just assume they are out and get the crank ground and new bearings to suit. You might as well change the cam bearings at the same time as they cost buttons and are easy to do.
Regards,
Tom