Low oil pressure after not running engine for some months.

[Chris KC]

Please don’t take this comment as being “ preachy” John, but I have found problems like this occur if the car isn’t used regularly, even just a ten mile tootle once a week keeps everything working well!

I don't disagree Ivor, however I admit I abandon my car shamelessly for long periods of time and have never lost oil pressure as a result. 

What I must add (sorry John) is that the practice of "starting the engine to circulate the oil" - especially if you plan on revving it up - is really to be discouraged. As an automotive engineering undergraduate many years ago I was taught that 90% of engine wear occurs from cold start-up - in other words only start the car if you plan on driving it. I have a neighbour who has owned a series of very expensive modern cars which he keeps in a lock-up garage, hardly ever seems to take them out but about once a week he comes down, starts them up, and sits there revving the engine for about ten minutes. I'd tell him not to (if only because it's bloody irritating) but from experience he's not really the type who listens.

[Ivor Hawkins]

I’m in full agreement Chris, I let the engine tick over just for a minute or two so the choke is off and get moving...I think I might get the Austin out and have a play in the snow!

[Chris KC]

I’m in full agreement Chris, I let the engine tick over just for a minute or two so the choke is off and get moving...I think I might get the Austin out and have a play in the snow!

Great idea!!

[andrew34ruby]

Please don’t take this comment as being “ preachy” John, but I have found problems like this occur if the car isn’t used regularly, even just a ten mile tootle once a week keeps everything working well!

 I was taught that 90% of engine wear occurs from cold start-up - 

It seems that starting up the engine causes a lot of wear, but whether you drive it after that makes little difference. Conclusion seems to be to start from cold as seldom as possible, whether you drive it or not.

[Bruce Nicholls]

I often wonder about this in my 130K mile Lexus Hybrid which often gets only just warm, even on a 10 mile trip. The engine stops and starts constantly on such a trip. Is it just the very thin synthetic oil that saves it? It burns no oils between 10K changes so it obviously surviving.

[David Stepney]

I believe that modern semi synthetic oils are better at adhering to the bearing surfaces that the old oils were, so that there is less damage on a cold startup. See also my comments posted on the Correct Grade of Petrol thread.

Going back to John's original problem, just as a thought: have the pump vanes become stuck in their slots?

[Howard Wright]

Hi All

I’m a bit paranoid about starting and leaving my Sevens running on the drive. Especially with the RK just having had a rebuilt engine fitted last week!

On the other hand my fully electric Vauxhall window van is completely immune. It’s motor only runs when the vehicle moves! I wonder how much energy that saves over combustion engine cars when stuck in traffic?

Cheers

Howard

[John P]

Thanks for all the suggestions.

I hadn't previously considered the pressure relief valve, but not properly shutting off would presumably explain the symptoms, especially as revving it quite hard did result in the pressure coming up to around 1/2 what I normally get when the engine is cold.

I'm assuming this would be because at high revs enough pressure is generated by the pump to give a reading on the gauge even if the ball doesn't actually seat properly.

I don't think it could be the vanes sticking in the pump as then I guess there wouldn't be any pressure and also centrifugal force would be assisting the springs once the pump is rotating.

I also don't think it's likely to be water in the sump as the oil level hasn't increased and presumably any water would be coming from the block and I'd have thought I would have noticed something that serious.   (The car was actually running fine when I last had it on the road).

I haven't actually done any further investigation as I don't have much room in my garage and working on the drive wouldn't be much fun in this weather.

I'm certainly hoping it's the pressure relief valve as that seems the least difficult / costly think to put right.    Just a pain to get at with the engine in situ.

John.

[Colin Wilks]

Regarding not starting the engine unless you mean to drive it, when starting the car after it has stood for a while I turn my engine over on the handle with the ignition off in order to get some oil pressure, and hopefully coat as many surfaces as possible, before firing it up. Am I wasting my time?

[andrew34ruby]

Regarding not starting the engine unless you mean to drive it, when starting the car after it has stood for a while I turn my engine over on the handle with the ignition off in order to get some oil pressure, and hopefully coat as many surfaces as possible, before firing it up. Am I wasting my time?

Colin I do that too. It's not a waste of time. It might do the engine some good, but also we get a bit of exercise.