Club 80-90 Forums

'Twere'nt bothering no one....

Well it looks like it fixed mine, replaced the sensors and then decided to take the sump off and inspect the oil pump.

The removed oil pumps strainer was quite blocked by what appeared to be silicone used to seal the sump pan on, as I had already brought the pump I just stuck the new one and I haven't had the buzzer since!

How big a job?

Not too bad, bit fiddly to get to all of the bolts and mine had been stuck on with silicone, best way I found was to count all the bolt holes on the new sump gasket so you know you've taken them all out.

So just drain the oil, remove the sump, pump is held on with two bolts and then stick it all back together. I ordered the rubber sump gasket from brickwerks and didn't use sealant, has a very slight leak but it's ok now.

So anyway, new high pressure senior fitted and BOD has disappeared.

Also had the gauge fitted on the low pressure tapping. This clearly shows the significant drop in pressure once the temperature gets up. I'll make a log and publish when I have more time for a few runs. It does drop right down though, so much that the low pressure light comes on at idle following a long hot drive. A little rev and the pressure comes up.

When I start up from cold and leave at idle I get at least 4bar. It goes up 0.5bar when I Rev to 2000rpm.

Once it warms up the pressure goes right down, but stills comes up with the revs, not not to 4bar clearly. I'll take note next time I sally forth.

My hot engine at 950 rpm my gauge (wet) reads
1.2 bar (18psi)

At 3000 rpm it reads
2.75 bar or 40 psi

20w 50 mineral.

Cold engine gives 4.2 bar or 60 psi

Science Boy. My DG also has low pressure warning after long runs
Basically, when the engine is heat soaked. I've replaced the oil switch for a known good one to no effect. I've replaced my oil pump, this had little effect. I've replaced the pressure relief piston and spring, this has improved it considerably although a long summer motorway run will induce a low P warning.
I have tried to inspect my oil pick up strainer with a video probe but couldn't locate it. I suspect either the engine core is knackered or the pick up pipe has a crack in it. Both would give a pressure warning.
Pressure is resistance to flow, caused by lack of compressible fluid, incorrect effort imparted on the fluid (worn pump) or excessive wear (no resistance - like removing a finger from the end of a hose).
Pressure has two components: static and dynamic. The static pressure is measured on our engines. The dynamic isn't. Think of driving in a car and sticking your head out the window. Dynamic pressure is the force that let's your hair flow, static is there even when you close the window - atmospheric pressure.

pv=nRT

Isn't that equation for gasses, not liquids?

Haha. You are quite right. Ideal gas law. Liquids are generally incompressible, but density and viscosity change with temperature. Need to dig out my old Chem Eng notes.

Kev, my cold engine give 3bar at idle.

When hot however it idles just shy of 0.5bar.
1bar at 2000rpm
About 2bar at 3000rpm


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ScienceBoy wrote:Haha. You are quite right. Ideal gas law. Liquids are generally incompressible, but density and viscosity change with temperature. Need to dig out my old Chem Eng notes.

Kev, my cold engine give 3bar at idle.

When hot however it idles just shy of 0.5bar.
1bar at 2000rpm
About 2bar at 3000rpm


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That would niggle me on a wet gauge.
I would consider those readings and know that sooner rather than later my engine bearings will deteriorate on a faster curve.
most wear is at low rpm so those figures would be an early warning

Might try for new oil pump?


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I wouldn't jump in buying oil pumps yet.
By all means take the cover off the pump and check the clearances and see if there's any visible damage.

Pressure isn't made by the pump, it's the resistance of the bearings that creates the pressure.