Oil Pressure Query

[Turboseven412]

Hi all, 

Just a quick one, at this time of year, how long after starting/driving does your oil pressure drop down to the normal operating range (mine would be about 5psi driving, 0 - 1psi idling).

Just asking as I'm unsure if I have a restriction or I'm just being a scaredy-pants and need to drive it for a bit longer.

Many thanks!

[Reckless Rat]

About 5 miles, until the engine is fully warm.

[Graham Barker]

My engine gives those oil pressure readings after about 5 miles.

[Turboseven412]

Thanks guys, I'll take it for a drive tomorrow and see what happens after 5 - 10 miles.

If the issue persists, and the jets are clear, would the next place to check be the oil pickup strainer?

[Reckless Rat]

You could try but I think you'll struggle to find it - there isn't one. The standard gauge for your car should be a 0 to 10psi one. They are not 100% reliable and are prone to sticking. A blocked jet is usually indicated by high pressure but if they are clear then it's probably just cold running that's causing your anxiety.

However, it is normal for the gauge to show maximum pressure until the oil is thoroughly hot. It is of course possible that a previous owner has had the oil pump refurbished or modified to increase running pressure. You'd need to ask what's been done to it during its life. It's not normal though for the pressure to remain high when hot at tick-over. Tap the glass to make sure the needle's not sticking.

[Colin Cooke]

Hi Turbo,

Last night, I drove about 70 miles in 6degC, and my oil pressure reading was about 1psi higher than I'd expect at summer type temperatures (5psi instead of 4psi at 40 mph).

I once built a 'new' engine, and took it for a 20 mile test drive in conditions below freezing. The oil pressure never got below 8psi. I put it down to the temperature initially, but then decided I needed to investigate. I found out that some new jets that I had fitted, were undersize. I drilled them out to 3/32" (I hope I've remembered correctly), and oil pressure was good. Not sure why the jets needed this - could they be 3 bearing?

And one other strange high oil pressure reading I had, was when the gauge was fitted on the slant (can't imagine what lazy person did that). Gravity did seem to affect the reading.

Hope this is of some use, in your investigation.

All the best,
Colin

[Reckless Rat]

I'm forgetting of course that ambient temperatures in the UK are a bit colder than where I am. When you do your road test it might be worthwhile removing the fan belt (or just take it off the bottom pulley and leave it safe with a cable tie) - an Austin Seven engine will take a long time to warm up in the winter and will happily run without forced cooling.

I actually use the oil pressure gauge as an indication as to when optimum operating temperature has been reached - even down here in the south of France it can take a long time from cold.

Best of luck.

[robert regan]

I never run with a fan belt in cold weather, Rob

[AustinWood]

We have a Renault 5 thermostat in the top hoae. Speess warm up nicely.

[Turboseven412]

Hi Colin,

That's a good point actually, the engine was freshly rebuilt by the previous owner but of course I can't be certain what he has actually done to the engine.  I'm sure the jets on my engine should be 1/16th so I'll measure some bits of wire and check that its a snug fit.  I've been using a piece of guitar string to poke down the jets and I think its a bit thinner than that.


I haven't been able to get the car out for a proper thrashing down the road today as I've been taking it for short drives up and down the road while I try to sort out a couple of grabbing brakes.  However I had the engine running for a good hour or so, driving it up to about 30mph briefly and the engine was hot enough to sputter some steam and water out of my ill fitting radiator cap (I may have overfilled the rad a little bit yesterday).  
Oil pressure was around 2psi idling and a max of 8psi fully revved up.  I will try removing the fan belt as suggested but really I think I just need to get it on the road and give it a good blast.  The pressure definently seemed to be coming down with time, but it is starting to get bloody cold up here in the North.

As I said the engine was rebuilt recently by the previous owner and he has used Silkolene 20w50 classic oil, and supplied me with some to use with it.  I've looked at the specs for the oil and it seems to tick all the right boxes.  I'm wondering if this is perhaps too thick for the time of year.  I might have read elsewhere on the forum people prefer a lower viscosity oil in their 7's