Check valves

[Harryblue]

Has anyone used these on their Turbo?

As I understand it, this prevents oil from seeping into the sump when the car isn't being used, thereby preventing oil leaks whilst it's standing.
I've seen people use them, and manual valves, on dry sump motorcycles, but the risk is that if the auto check valve fails (or you forget to switch on the manual one) then you've stopped oil flowing from your oil tank into the engine, with obvious catastrophic consequences.

If I understand correctly, once the car is running and the oil pump is pumping, then the pressure opens the check valve and it flows as normal, then when it shuts down the valve closes and prevents oil slipping by into the sump, I think they call it wet sumping or something.

Oil Inlet Check Valve (72-89) 911/ 930

SKU: (RS-30A) Rothsport (72-89) 911/ 930 Oil Inlet Check Valves eliminate oil migration from the oil tank to the engine reducing excessive smoking on start up typical of cars that sit for long periods of time.

rothsport.com

 

[Luddite]

Hb, seems you well understand the risks in terms of m/cycles and I suspect it is no different in an air cooled Porsche.

I think in air cooled Porsche terms, the issue may well be that as best I can remember the aircooled car`s handbook instruction was just to drive off as soon as the engine was fired up... I suspect that may have been when a Porsche might have been expected to be driven fairly regularly or perhaps at least once a week. However with many Porsches of that era now being laid-up for months at a time, I suspect as the result of the oil tank being mounted higher than the engine casing, that gravity seems likely in time to allow the oil to drain into the engine through the oil pump gears...?

I think other than the issue of having engine cases split vertically as per many old Brit m/cycles, and leaving the floor of the garage well lubricated, the issue of having a high level of oil in the crankcases, might just lead to some degree of excess crankcase pressure build up when the engine is initially fired up, and perhaps more so if it fires up immediately, and is revved to any degree, to warm it up somewhat...?

My guess is that it might be best to fire it up and let it tick over for a minute or so then drive off keeping the revs down till it`s engine temp/ oil level gauge displays that all is looking good...?

Just thinking in type and claiming zero expertise...

 

[Harryblue]

Yes I think basically that's it, the idea is that oil is not stored in the sump like a wet sump lubrication system and it's stored in a separate tank and only pumped around the engine when it's running. The problem if it gets into the engine when it's not running is that it can then take it's time finding every opportunity to escape onto the floor, or even worse all over your engine and catch fire.

So in theory the check valve is a good idea, but if it fails at any point then there will be no oil flowing around the engine.
I know a chap who had a manual one and forgot to turn it on and destroyed his engine when it ran without any oil being circulated, so in general the advice is not to bother and simply put up with it, I usually drain the sump every now and then and put it back in the tank, and if it's stored for any length of time I take all the fluids out anyway.