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Old 04-01-2021, 05:26 PM
Vans101 Vans101 is offline
Join Date: Apr 2016
Location: San Jose
Posts: 72
Default Fuel Pump Garlock Seal Leaking...Oil Separator???

After this last flight I noticed a fair amount of engine oil dripping from the flange drain drain pipe of the Romec engine driven fuel pump. It was a fair amount of oil dripping down and that pipe has always been dry so that is concerning.

I asked Don at Airflow Performance about this oil leak because the Romec pump is new and I bought it from him and he said that the oil leak must be coming from the "Garlock" seal installed in the fuel pump mount /drive accessory housing.

Has anyone experienced this?

The engine was rebuilt about 12 hours ago so I wonder if the seal has gone bad already...OR...perhaps something else is in the mix.

I do have some concerns about the Oil Air separator...I mention this because there has been a fair amount of oil leaks in the engine (pan gaskets, mag cover block off gaskets, cylinder head oil drain hoses, turbo oil scavenge pump housing flange) and I am wondering if the oil air separator (it is the mini unit) might be the culprit in not allowing the engine to vent properly.

The engine is a Lycoming 540 with a 1 inch diameter vent fitting at the top of the accessory case and I have installed a 1 inch ID hose from the crankcase fitting to the side of the separator. The separator is mounted above the top of the engine and there is also a 1 inch ID hose and a 1 inch ID aluminum vent pipe that points straight down from the separator and the aluminum vent pipe exits the bottom of the engine compartment.

The end of the vent pipe is bevel cut at a 45 degree angle with the beveled opening pointed toward the back of the airplane. I read that the beveled cut should not point forward because that makes the cut into an air intake scoop and that would pressurize the crankcase and if it is pointed backwards then there is a venturi effect that causes a negative pressure area helping to scavenge the engine.

I also installed a "Whistle Valve" opening on the side of the aluminum down pipe.

The separator is installed according to instructions and the drain hose does indeed have a continuous downhill slope from the bottom of the unit.

For those that are running an oil air separator, where on the engine did you install the oil drain back line?

On my engine both magnetos have been removed so I tapped into the magneto block off plate with a fitting so I presume the oil drain back will just drop down into the accessory case.

So sorry the long stream of consciousness but if you all have any ideas I am all ears.

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Old 04-01-2021, 06:13 PM
jrtens's Avatar
jrtens jrtens is offline
Join Date: Apr 2018
Location: Utah
Posts: 173

Yes. Garlock seal leaks are fairly common in the accessory drives.
I had one leaking into my #2 alternator on my Cirrus.
They may not have replaced the seals on your rebuild.

The service center replaced it quickly although I think you need a special tool.
12iS SLSA #5
Salt Lake Int'l
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