very high oil pressure

[jhhturner]

I have an unflown Nipper with a 1834 VW. The small amount of paperwork that I have relating to the engine indicate that it was built by the owner before last from a Mexican crankcase which Barry Smith machined for the larger cylinders and supplied bearings, gaskets etc.
The engine has two oil pressure relief valves. I understand that the one nearest the propeller with a long spring prevents over pressure to the oil cooler . The rear one with a short spring is the oil pressure relief valve proper.
The engine had not run for about a year following the death of the previous owner. When we started it the oil pressure was only about 20 psi at 1500 rpm ,dropping to 5 psi when warm. Investigation revealed that there was only a spring in the rear relief valve. I ordered a new piston at a refreshingly cheap non aviation price and fitted it. The oil pressure is now about 40 psi after start , but rises within about 30 seconds to 90 psi when my courage fails me and I stop it. The new piston is not a tight fit and comes out with the spring ,so I assume that it's not stuck.
I've cleaned the crankcase hole and swapped the two pistons with no effect.
Does anyone have any suggestions ?

[JAB]

Without stating the obvious, have you checked your gauge and or your transmitter. I had a simular problem, checked both out to discover it was the transmitter.
I have a split quad oil pressure, temp, cht and egt gauge with a transmitter by Westach.
Hope this helps

JAB - XD

[jhhturner]

Mine is the same quad gauge and I did try a mechanical gauge when I had the low pressure problem . Since it agreed at low pressure I have assumed that it's correct at the high pressure end-hope I'm right.

[JAB]

I have just had a chat with John who has G-AWDA. He had the exact same problem. His remody was to change the relief springs,this was on the advice of Barry Smith, all is well now.
Suggest you give Barry a call.

Cheers JAB

[jhhturner]

Many thanks - I shall call Barry on Monday.