1.8T Oil Leak Troubleshooting

I've been working on my first rebuild of a motor and been stuck for awhile trying to track down oil leaks. Thought I'd post my progress here in case someone see's something obvious. This is a 2001 1.8T AWM.

1. On first start engine was leaking oil from the front. Tear down showed the front crankshaft seal was wet. After installing a few more crankshaft seals and having the same leak I eventually learned the difference between a rubber/spring type seal that was on there versus the newer PFTE seal type. After getting the audi seal install tool and cleaning the surfaces to install the PFTE dry I solved the front crankshaft seal leak. During these repeated tries to get the front crankshaft seal to stop leaking I went ahead and did 20 minutes of the initial ring seating run in since I was worried about losing my hone.

2. Engine still leaking from the front, crankshaft seal is now perfectly dry, but there is oil all over the front underneath the timing covers. I reassembled with the timing covers off and the front radiator pulled out in what audi calls "service position". This let me record a video of engine start. An oil galley plug right above the crankshaft seal was pouring out oil. The machine shop had installed these plugs as part of the block cleaning. As I was drilling a pilot hole to use a slide hammer to remove the plug the plug spun out freely on my drill bit. The machine shop had used 9/16 welch plugs, I reinstalled a 14mm that the engine spec calls for. Started engine again, still leaking but less from the plug I just installed. I removed the plug which required a slide hammer to get free this time. I reinstalled with Permatex #1 and let it cure 24 hours.

3. At this point there was no leaks, I did a fresh change with another 5w30 conventional and did 300 miles of run in. It was keeping steady oil levels during run then I changed over to 0w40 synthetic. At this point the car started leaking oil again, but not immediately, I discovered the leak while fixing a broken boost controller. The leak was not from the nose, its now leaking from the mid/rear driver side.

4. I had only replaced one galley plug in the front. There are 3 total, 2 up front and one in the rear. I repaired the other front galley plug and resealed the crankseal housing and installed another crankshaft seal as part accessing the other front plug. I removed the motor to get at the last plug. Unfortunately that plug was completely dry, I installed a fresh plug with permatex #1 anyway. The rear main seal was also dry. I inspected the motor for leaks and found oil around the oil filter housing/block. This is located in the driver mid rear. I also found a ripped pcv vent hose (original I did not replace during rebuild). So in addition to redoing the rear galley plug I installed a new audi oem oil filter housing gasket, pcv breather valve, pcv hose to replace the torn one and new pcv breather o-ring. I had used an aftermarket gasket kit when doing the rebuild, I replaced these hoses/gaskets/orings with audi oem this time.

Got the motor reinstalled and started her up, massive leak from the nose again. Driver mid rear is dry. Just finished getting it open, front crankshaft seal is dry but oil all over everything. Going to reassemble with the covers off again and record another video to try and see where the oil is coming from now. Maybe I did a poor job of the galley plug install.

That's the current state of affairs, pretty discouraged thus far but powering through. From a fully assembled car I can strip it down to the crankshaft seal in about 30 minutes flat now!

oh wow you have had some issues, my initial thoughts were that you could be getting pressurizing in the crankcase causing this repetitive issue it would pay just to check that and also check the oil level is correct to the amount it could have in it,

Regards Ross

I thought pressurized crankcase may have been an issue as well. I had replaced the pcv regulator as part of the rebuild and I did check that I'm getting airflow back into the intake from the crankcase by disconnecting where the regulator connects to the intake and feeling for airflow. They call this pcv regulator the "hockey puck". I had replaced the PCV elbow, main tubing and cleaned all the hard pipes. Oil levels are right where they should, measuring the fills and accounting for a deeper oil filter.

Thanks for the suggestions, I appreciate it! It's a race weekend so going to resume troubleshoot next week.

Solved the leak issue. A front oil galley plug had damage on the galley bore where the plug seats! There was a chunk/groove missing on the top of the bore wall at the deepest part of the bore. When I seated the plug fully against the lip this allowed the groove to get completely around the plug.

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My solution was to redo the plug again with permatex #1 but only seat the plug flush with the block face to minimize the impact of the groove. 100 miles of no leaks so far!! I didn't notice the damage because its a groove on the top and its hard to see, have to sit on the ground looking straight up with the block in the motor.

Motor is running strong, shaking the car out at open test day this coming friday.

well done this is great news

Regards Ross