Drilled hole in engine cap

[Rosemore]

I'm wondering why a previous owner might have drilled a hole in the engine cap. It's one of those plastic replacements.

The oil pressure light does flicker sometimes and the gauge reads 0 only when the car is hot and idling - there is plenty of oil. I was wondering if this could be connected to the cap hole?

The car has undergone valve change so that the car takes unleaded - not sure if this is relevant.

[King Kenny]

If you mean the oil filler cap then I do not think it will have any effect on the running of your car. Possibly the previous owner had fitted some sort of breather tube to it.

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[myoldjalopy]

Some engine set-ups require a vented oil filler cap. It may be the PO got the wrong, non-vented cap and drilled a hole to compensate?

[Bill_qaz]

There are vented and unvented caps depending on your breather set up. The stud circled usually has plastic strap to filler neck to avoid losing the cap.

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[Rosemore]

I see, I bought a replacement which has a breather hole under the cap. I'll change it over.

Thank you all.

[SEROWMANMICHAEL]

Hole or no hole in the Cap will make no difference to the oil pressure,you either have a release valve problem or the oil pump is getting tired

[philthehill]

Plus worn crankshaft bearings!