Porsche 911 rothsport oil inlet check valve installation 911 (1965-89) – 930 turbo (1975-89) pelican parts diy maintenance article 101 gas station


One of the common problems with classic 911s can be a plume of oil smoke from your exhaust on start up. This is especially true for cars that do not get driven regularly or have sat for a while. While this is not harmful to the engine if after starting you get the engine up to operating temperature it can be quite embarrassing. There is nothing worse than having all eyes on you as you step into your 911 only to have a gigantic smoke screen come from the exhaust on start up.

The majority of this smoke on startup comes from oil from the oil tank migrating back into the motor. Rothsport has come up with an ingenuous solution to this problem by designing an oil inlet check valve that restricts the flow of oil back into the motor and opens instantly on start up. Installation is quick and easy and a perfect solution for cars that sit for long periods of time. Note; the valve is clearly marked with an engine side and a tank side. Failure to install the check valve in the right orientation will lead to oil starvation and catastrophic damage to your engine. Please make sure to read all the instructions and double check the orientation of the valve when installing.

The oil migration problem happens in the S-hose and while you can drain the oil and install the check valve without removing the hose from the car we highly recommend installing a new S-hose. The hose is prone to degradation (especially if the car sits for long periods of time) and it is easy to do and cheap insurance. See our tech article on S-Hose replacement.

I have used on late model SCs and Carrera with great success. that is the late model 964 or small orifice oil passage or restrictor as it is sometimes called had created a flow problem with the camshaft getting a very low volume of oil although the oil light stayed out and the oil pressure was 20psi at idle, the system cavatitated and created a horrible camshaft lifter noise. due to the early design of the sump suction pump it had no enough drain down to the sump for suction pump to do its job therefore based on these results I CAN SEE WHY THE OIL VALVE WASN’T ABLE TO GET A DRAW TO THE SUCTION PUMP! I think ROTHSPORT products are top quality AND WILL GIVE A UPDATE ON THE 2.7 SOON AS I CAN FIND THOSE OLD SCHOOL RESTRICTORS I TOOK OUT OF SOMEONES SC

Comments: 2.7 litre had no oil pressure and was not circulating thru external cooler lines after install of this device upon removal the engine was back to normal operation and the oil light stopped flickering, am wondering why I got these results

Comments: I’ve got an ’86 3.2 which fouled #5 spark plug after approx 17k miles. I’m aware of the valve guide issues with these engines. Since it was only #5 and that appears to be the cylinder closest to the oil migration area, I wonder if this check valve might address this issue, hopefully allowing me to postpone a top end overhaul for a while. Your thoughts would be appreciated

Comments: You guys do a great job but there is an error in the catalog section, at least for the early cars, maybe all cars. For a ’67S you list the valve suggesting the replacement of the long return hose, not the short S-hose. This could have dire consequences since the valve would stop flow back to the tank. I hope this helps.