Perkins AD3-152

I'm fearing the worst - worn piston rings, causing "blow by" into crankcase. Is this a common problem?

In our case, it was aggravated because the loader frame interfered with access to the oil filler cap, and careless employees used dirty funnels to add oil. Sand and dirt was added every time.....

On the flip side, the Perkins is one of the cheapest engines to overhaul. Aftermarket parts are half to two-thirds the cost of some other makes - probably because of the large numbers of the engines around, and standardization - the 3.6" bore three cyl and 4 cyl in the same model series (indirect injection vs. the later direct injection (slanted injectors)) take take the same sleeves/pistons/valves/rings, with a couple of minor variations.