Rootes1725cc

Hi all, my 64 super minx has developed a 2 or 3 second lack of oil pressure on start up. Doesn't happen all the time but is worse if she's not used every other day.
Noise goes away as soon as light goes out and only happens on immediate start up sometimes.
Been told it may be a sticking relief valve but surely this would mean it would have to stick open to allow flow back to the sump creating no flow for the engine. To stick open surely she would need to have over pressured first on a run?
Been also told it maybe the non return valve stuck open on the oil feed pipe to the timing chain.
Any suggestions and fixes gratefully appreciated.

I recommend checking to see if the plunger in the pressure relief valve is steel or brass.
If brass, they are known for sticking and I would recommend replacing the whole oil filter assembly.

From what I have seen there were three different types of relief valves used during the years.

Below is one of the earlier ones from my 1962 Super Minx.
Notice that the cap, spring and plunger are three separate pieces.
In one of the later versions, the relief valve comes out as one unit and cannot be easily adjusted.

The advantage of the earlier version is that you can easily add some small washers to the inside of the cap to add additional spring pressure to improve oil pressure at idle in older engines.
Be sure to test oil pressure when cold as well, on my first attempt at this I used too many washers and had 90 lbs cold idle oil pressure!

Here is a picture of the "all-in-one" type of pressure relief valve.
You cannot replace one type of relief valve with the other without replacing the complete oil filter mount assembly as they are not compatible.

Here is a discussion on the Aussie forum that has some good info that might be helpful.
http://www.sa.hillman.org.au/TT_OilFilterBase.htm

Many many thanks for your help.