Oil Pressure

[Bob Fawkes]

Has anyone had this problem? I've a 1979 +8 with a standard 3.9L engine, have recently done 2 track days. After each of the days, when the engine had cooled down, on re-starting it there is no oil pressure. The 1st time this happened I packed the oil pump with vaselene & successfully re-primed it. The 2nd time was yesterday at Silverstone, is the pump worn out or somehow air getting in? The sump is not low on oil, I'm using 10/40 grade oil, got any ideas?

[Mary Lindsay]

Hi Bob,
It sounds like you need to baffle the sump. We used to get this problem with our Plus 8 when using the car on the circuit especially under heavy braking or cornering when the oil was hot. You get oil surge away from the pick up and this starves it of oil. It pumps fresh air and that is why you need to prime the pump with Vaseline.
Best wishes,
Mary

[Andy Green]

I agree with Mary

I suggest you remove the sump and take it to Pete Mulberry,he will weld in a baffle plate etc

Then re fit using silocan or maybe a gasket,thicker ones are available from Rimmer/e bay sites as sold to fit range rovers etc

[Tim Clark]

Hi Bob

Absolutely concur with the above; baffled sump will sort this.

You may also like to consider upgrading your oil pump to a high pressure version (while your at it some race oil)

[Jim Mountain]

and an oil cooler if you don't have one already

[Bob Fawkes]

Hi, Both the sump and I are baffled & there's an oil cooler. I think I'll strip the pump tonight to see if there is any wear. I wonder if something can go wrong with how the pressure relief valve seats?

[Lorne Goldman]

Hi, Both the sump and I are baffled & there's an oil cooler. I think I'll strip the pump tonight to see if there is any wear. I wonder if something can go wrong with how the pressure relief valve seats?

Relief valve is the most common cause of your symptoms...though I have also seen cases where the sump pickup had an issue..even one case were it detached entirely.

If it were me (and it has been) I would remove the pump base and either replace it or refurbish it. (To refurbish click here http://tinyurl.com/6er2vp8 ) I would change the pump gears for new and buy a "tadpole" to replace the relief valve piston. The pistons have a habit of sticking, often at the same place, which is very serious for all and racer especially. Tadpoles solve the problem. You should be able to purchase one from Real Steel or J.E. Engineering or even on ebay. They look like this. http://www.britishv8.org/Articles/Rover ... pgrade.htm and they stop the valve from sticking. What is possibly happening is the high pressure from racing is pushing the relief valve to the point it sticks open. Then, when the engine cools down, the metal shrinks a bit and the oil thickens and the valve behaves..until the next time. You could also very lightly hone the relieve valve canal or lightly sand it inside with the same fine sandpaper you use on the base surface. But whether this works or not, a Plus 8 racer should take all precautions and tadpoles are cheap and easy to install.

Not finished yet.. (smile) If you wish to be able to adjust your oil pressure generally use an adjustable oil pressure regulator. This is a simple affair that replaces the threaded plug for the relief valve. It incorporates a Allen key adjuster that tightens the relief spring tension and therefore the oil pressure (though NOT at idle..for that you need another modification which I have never tried or needed to). The adjuster is available from http://www.taperformance.com/
Part # TA1502. I have never tried more than 10lbs per 1000rpm.

Lorne

[Bob Fawkes]

Lorne, thankyou for your very sound and accurate advice. I have actually done exactly what you recomended & touch wood, problem solved.