I am going to submit this at the risk of being shot down in flames by the moderators, as it concerns a corsa 1.0 engine, not a Vectra (I do own a Vectra as well!). The reason I have submitted it here is to hopefully get some experienced advice from proper mechanics etc, as the Corsa forums are populated by airheads and are a waste of time. So, here goes:
Engine in question is a Z10XE 1.0 ltr. The timing chain slipped causing a coming-together of the pistons and valves, resulting in a damaged head and 2 holed pistons. I obtained another engine that had suffered a similar fate but not so excessively, and used the head and 2 pistons from it to repair the original engine. The block identifying letters were a bit confusing but I very carefully measured the pistons and bores (using proper instruments) and they all are the same on both engines. After fitting a new timing chain and tensioner, the engine is now running really well, I have done a compression test and all is good - but, the engine is burning oil. I have checked the valve stem seals against a new one and they look fine, no deterioration and as tight a fit on the valve stems as a new one. I did actually replace them on one cylinder which wasn't easy with the head in place but decided due to the condition of the existing ones it was not worth doing the rest. I reckon it's burning about a litre every 750 miles. I am wondering if using pistons from another engine, albeit the same mileage and size etc, is causing oil to bypass the control rings and get into the chambers, but it seems like a lot of oil is going that route if so?? any ideas anyone???