Chasing our first oil leak

Quick timeline:

1. Changed the oil at 119k Miles or so (Jan 8)

2. Got my UOA back and it recommended fuel injector cleaner because it looked a bit like we might be getting gasoline contamination in the oil (Jan 16)

3. Added FI cleaner to a full tank of gas and drove around. (Jan 18 it arrived. Didn't add it for another week?)

4. Noticed a small oil leak on the floor (Jan 29)

5. Located what I thought was the source, and then did a pretty thorough cleaning

6. Had leaks overnight but then they stopped

7. No leaks since. (? Not sure why)

I am not associating any of these events, simply laying out the timeline of what happened. Step one for me in t-shooting something is usually 'what changed'. The weather was poor for much of this timeline so it is hard to tie things together since I was not driving much. Since it has stopped, my current theory is perhaps I had a tiny bit too much oil in there and it came out the RMS when I drove enough to really get the temp up. The dip stick says it is not full though, so I'm not sure about that. FTR I would be fine if it never leaked again. I don't need to know why.

The basic process of chasing down a leak, any leak is to:

1. Look for where the oil is dripping from, and follow it to wherever it actually came from.

2. Clean the areas involved as best you can and then monitor things to confirm your leak(s)

3. Once you know where it is coming from, you can figure out what repairs may be needed. Or not.

I do want to call out this excellent article from the folks at FCP Euro on common air-cooled 911 oil leaks. I read it top to bottom a few times. Thanks! https://blog.fcpeuro.com/find-fix-common-oil-leaks-classic-air-cooled-porsche-911

The process is easy on paper, but not always so easy in real life under a dirty 35 year old car.

To keep this terse, I'll just follow the pics I took along the way.

Here is the leak as we found it on the 29th. I had just lifted the car where it was to see better. it seemed pretty far forwards for oil.

I checked the newest hose I had replaced. (what changed...) Dry at the engine side...

Dry at the tank side.

Checked the rear engine line. Nothing exciting, and no way for that drip to move forwards along the chassis

The rear lines don't look great, but they are not the issue.

Here is where the drips were coming from, they were running from the bell housing down to the lowest point on the transmission. You can see it running from L to R down that ridge.

Oil was coming out from what appears to be an inspection window (or drain hole?) in the bell housing. (that is the ring gear you can see inside, I think.). Based on the location, it could be the thermostat (on top of the engine), the oil cooler (above and just in front of this) or the rear main seal. Since it stopped we don't know, yet. I have to keep monitoring things.

So I got the car up on the quick jack in the driveway, let the engine run until it was up to temp and then gently scrubbed it with degreaser and used the mild head (for spraying on soap) on our power washer to rinse it off. Scrubbed the tank...

Scrubbed the passenger side...

scrubbed the driver's side

I do this with the engine running for a couple of reasons. First, the heat helps loosen the ancient grease and dirt and second, the water evaporates quickly and you don't leave water all over everything. It's more like driving in the rain.

And now we drive, and observe and see what happens.

Feb 5th

Drove about 40 min all in, grabbing groceries. After I got back, my leak was back. So sitting doesn't seem to be an issue, but driving is. Same spot. I need to do more cleaning and inspecting to nail down where it is coming from.

I also went through my old pics and found this one from about a 2 months after it was delivered:

Yup, same spot. Wet. It was not dripping, but it looks like this has been a while in coming. It's hard when the whole bottom of the car has this kind of coating on it, it's not clear what is causing what.

Feb 11, 2023

I took the day off from work Friday and spent the morning scrubbing the bottom of the car and seeing how high I could get the temp. I scrubbed to see leaks, and I ran up the temp to see how high the oil level would indicate. Had I put in too much oil?

The answer is yes I did, and for a couple of reasons.

1. I did not get the car hot enough when I was checking the level; it needs to be hot hot.

2. I had previously aimed for halfway on the gauge just arbitrarily. This time I tried to fill it, and even though it was ok on the dipstick (not over), after reading a lot on line, it seems that mid-way is really the target even in a hot engine.

3. So it wasn't over by much, but just enough to have extra pressure and it chose the RMS to come out. My old Triumph would push oil out the dipstick if it went over. I guess they all have their spots.

So I put on some heavy rubber gloves, let the car cool off and once it was safe, I turned the sump drain plug until it was just coming loose. I held it in place but on an angle to let oil come out in a controlled fashion. I chose the sump rather than the tank after more reading and the point is that there is less oil in the sump, so this is easier to do in a more controlled fashion. I drained what I thought was about a quart. From reading it appears that between the low and high marks on the dip-stick is about 1.8 quarts, so my logic was to get it back to the bottom of the range and then add back a little to get the gauge to the middle again.

I removed some oil, checked it and the gauge was down towards the bottom. I took it for a real drive, got the temp up and topped it off when I got home. I have not had a leak since Friday and I've probably got 70+ miles on there since fixing this. The bottom is still clean and dry. Lesson learned!

The cautionary tale I kept running into is an owner who would take the car to an oil change shop and they would then fill it cold, up to the top of the dipstick. That would be 2 quarts over the high end - give or take. The issue is (so I have read, I don't know) with the oil level too high the crank foams up the oil and that foam starts coming up into the intake and can get on to the engine and cause a fire (in addition to whatever leaks occur).

I was lucky that I was only a tiny bit over and that just forced a very small leak.

I had filled it to between 1/2 & 3/4 but the engine wasn't warm enough. Once it got nice and hot, the level went almost all the way up. This is too high, and it let me know.

Still between marks on the dipstick, but too close to the upper one.

Cleaned up the G50. Not everything came off, but it probably hasn't been this clean in 25 years.

The case is still clean and dry after some real miles.

While I was filthy and cleaning anyway, I got as much as I could up into the timing chain & rocker areas so we can see what is going on there.

Ditto on the other side of the engine. With everything clean and dry, any new leaks will stick out.

March 6 2023

The car is over 120,000 mi now so it has been nearly 1,000mi since it stopped leaking. Life is good!