Last night I was sitting pretty, so to speak, but this morning I decided to fit the wooden blocks and springs to mount the front fan assembly and check the clearance on Brian’s engine. After torquing up the pulley centre bolt, I noticed a few millimetres of clearances, but on rotating the turbine or fan, it scraped the top of the sensor.

I have never seen a misshaped turbine before, so I tried several different ones I had lying around, and surprisingly they were all misshaped, with the resultant wobbling just catching the top of the sensor at some point, so obviously more clearance was needed.

I had two options change the sensor, or recess the sensor some more, and as all my work on the sensor was completed and it is a cost effective (aka cheap) solution with excellent sensitivity, I was reluctant to change the former. This meant recessing the sensor into the timing cover. As I looked at this, I thought I’d check the oil light function, and this too was just too tight a fit, such that the oil light would never illuminate, which isn’t a bad thing, but it isn’t how I intended things to operate.

So a quick 3D tweak was in order, and this has been passed onto the 3D CNC fabricator. Slightly annoying for him, but better for us all. Oil light switch surface has been reduced in thickness (blue area) in the picture below, and below this the recessed area to add more sensor to turbine clearance. Not quite as elegant as I’d like, but it’ll do for now, and after testing there might be a slight refinement for the next batch.





PS I thought I would weigh this part, and check the calculated weight in the CAD model versus the actual weight. The CAD model suggested 719 grams, but the actual weight was 723 grams, which is pretty close, and well within 1%. Incidentally, the standard part weighed around 530 grams, but this new timing cover is considerably thicker in places.