The 2001 CLK55 engine sprung a leak, evidenced one morning by a visible oil puddle behind the right front wheel. It was a narrow lake of oil, probably no more than a couple tablespoons, originating near the rear of the engine. After putting the car on ramps I crawled under to take a look.

I uploaded the photo and had a bit of consultation with ChatGPT as to the possible source of the leak, and eventually discovered there was oil on the front of the engine below the oil filter housing, and a bit near the oil filler cap.

The yellow arrow points to the oil filter housing, which needed to be removed. I feared the worst, but found that it is a simple job. There are two rubber seals between the filter housing and the finned oil cooler, attached with four bolts removed with a T30 socket. The filter housing also has upper and lower halves, with a rubber seal between them. These are held together with a large hollow “bolt” that requires a 46 mm socket for removal.

When I first spotted the oil, I was tempted to donate the car to charity. However, what I feared would be a time consuming, difficult, and expensive repair turned out to be simple and straightforward.

I am an advocate of AI for help diagnosing car issues but ChatGPT was a bit off with this repair. First it insisted that I could replace the oil level sensor without removing the oil pan, telling me that it was removed from bottom of the pan, held by 3 bolts. NOT!

And then it was pretty clueless about the 46 mm bolt securing the upper half of the filter housing to the lower half that bolts to the engine block. By providing photos and working through it, I’m hoping it got a little smarter.

Next up, in a few thousand miles, replacing that oil level sensor. And then… fixing the ABS/ESP/BAS fault, which means having the pump rebuilt.