Turbo Oil Leak

As some of you might know I have been chasing a leak in my turbo since last fall. It was reported to me that Tweety smoked like an old Chevy. As of today I am still chasing. At first it seemed that the bearing in the turbo were leaking past the seal. The seal is a ring type and after examining it and the condition of the bearings and shaft of the turbo, I concluded that the turbo was OK. Several other issues however were present. First of all my cold oil pressure was over 60 PSI and the after warm up it is 40. Because of cooling problems I changed oil to 20 W 50. This was a mistake, because it created less flow and more pressure. I have now gone back to 10 W 30. The warm up of the oil today was quicker. The pressure was still at 55 plus during warm up. A quick check of my VW book tells me that the engine needs between 25 and a max of 45 psi. The Ford turbo engines all list 50 psi as the correct pressure.

An associate of mine told me that every production turbo aircraft engine utilizes a scavenge pump to pull the hot oil out of the turbo. After looking at my setup, I can see that the turbo return oil is trying to force its way back into the case at the oil sump, below the level of the oil. After removing the return line, it is obvious that the return oil port is below the oil level in the sump area, because two quarts drained out with the line removed. I have decided to install the two stage Vanagon oil pump and use the Transmission side of the pump as an oil suction line for the turbo. Below is a picture of the original pump and then pictures of the two stage Vanagon pump.

The original type 4 pump uses the pump portion which inserts into the engine to support the drive shaft and to provide passageways for the oil inlet and outlet. On the type 2 Vanagon pump this same space is used to house one set of gears. The overall dimentions of the type 2 pump is the same with the exception that the exterior is countoured to only provide space for the gears. On the type 4 pump the exterior provides both porting and space for the gears, utilizing the wasted space of the type 2

With the Vanagon pump there are two separate pumping chambers, each separated by a thin plate. Each chamber has its own set of gears and a separate inlet and outlet for the oil to flow through. The gears for the engine oil pressure are about 1/3^rd larger then the transmission side of the assembly. The drive gear of each set is on a common shaft with a keyway for each of the two gears. The drive gear shaft is in direct contact with the distributor drive gear. The other two gears are on a shaft and turn freely. An additional port on the pressure side of the pump is provided for the use of an oil cooler.

Installation is nearing completion and below are a few pictures of the progress.