Changed the oil and filter a few months ago and noticed the pressure a bit lower than usual. Used Comna classic 20w50 and just assumed it might be a bit thinner than the previous oil.

Started her up yesterday afternoon standing for a while and the pressure went straight up to 40psi which is the normal cold pressure but dropped to about 20 when revved, normally does the opposite. Also sounds a bit graunchy.

When I get a chance I'll drain her down and take the pump cover off, see if there's anything odd in there.

Any ideas?

Check the oil relief valves and for any shiny particles in the oil.

Cheers Keith's

Soon as I'm over the flu ill have a go at it, forgot those valves tucked underneath,  good call

Thats curious - almost exactly where I am at the moment

Last trip out, engine fired up with full oil pressure, but when going along slowly or tickover, the oil pressure drops quite dramatically to the point I`m not actually happy driving it.

Need to also drain it out and see what it going on inside and I`m going to remove and service those oil relief bits as well.

Interesting to share findings on here 

Dave, yours is how mine started, almost as if the oil was too thin. Now it's reversed and drops when the revs increase.

A common issue giving oil pressure reading oddities is from engines that have had silicone based sealants used on them. Bits of silicone don`t dissolve in hot engine oil. Old school wax based sealants do. It could well be that a bit of crap is in one of the relief valves or both if the engine is based on a 1600 block. If crap has got to the relief valve/s it will probably be in the wrong side of the mesh filter as well. (Assuming you have the original strainer still fitted).

Got an external filter fitted, I know that doesn't catch everything,  has anyone got a diagram showing the oil path routes?

Here is a good one Dave https://zuczek1302.com/2018/12/21/the-air-cooled-vw-engine-oil-system/

That's brilliant keith,  thanks

Had a similar problem a few years ago it was a sticking valve, replaced them and the springs with CSP items.
My engine is the later type with the two valve setup.

VW Oil Control Valves

Cheers Chris

That's a useful little article Chris,  were did yo7u find it?

From the book How to rebuild your Volkswagen air cooled engine by Tom Wilson

 

Mine is a 2 litre lump, so slightly different, but I guess also similar enough with the pressure relief valves, which is where I was heading -

However, finally got around to draining the oil out over the weekend into a large oil catch can underneath, and I swear I spotted something, but not certain. As I removed the sump nut and all started to drain, it was almost as if I had a small amount of "gloopy" liquid come through, maybe an egg cup full, but almost runny jelly for want of a better description. Colour of oil is ok, and I`ve tried to pour out the contents to see if I can find this lump, but its not there. Did I dream this or was it a thing?

I`m now going to refill it with cheap crappy oil and run a full engine flush though it just in case and then strip out all the strainers, filters and pressure relief valve.