PREPARATION

As fellow enthusiasts we understand the reason you want to recondition and preserve your components is that you value them – so we will treat your treasured items as if they were our own. Some people express concern about blasting gasket surfaces and delicate components so we will only use techniques and processes which are proven do no damage. While bead blasting does not remove material and will thus do no physical damage to any surface, as policy we will not directly blast gasket mating surfaces, bearing housings etc.

 

If blasting media isn’t completely removed from components before being assembled, it will cause damage. We take great care to shield or mask gasket surfaces or bearing housings and plug or block oil-ways and galleries but we never assume there has been no media ingression; we scrupulously wash out and blow through all components. Rather than writing in detail about the lengths we go to please follow this sequence of pictures and notes below on how we treat different components.

We make great use of a number of these perforated rubber mats components to prevent delicate surfaces from getting scratched or otherwise damaged during the blasting process. The perforations in the mats enable blasting media to flow or drain back into the sumps of the blasters. We also use similar protective matting on work benches during preparation and finishing for similar reasons.

We stock a large number of these EPDM bungs in a wide selection of sizes for blocking blind holes, oil galleries etc to prevent ingress of blasting media.

BMW boxer crank case pushrod tube holes are tricky to block because they have a 30 degrees included angle taper, making our EPDM bungs are unsuitable. These truncated conical blanking plugs and washers were made specially, turned from acetal copolymer, which is free machining and dimensionally stable. We use similar truncated cones fixed with allthread to protect fork sliders. Due thanks to Steve Scriminger from Scriminger Engineering.

Crank case with oil pump housing and rear main bearing masked and blocked. The top bolt has a nut behind the plastic spring plate so the bolt head presses the blanking plate (the lid of a screw top jar) into the old main bearing oil seal thus preventing it from being dislodged by blast pressure.

Timing case crankshaft and camshaft bearing apertures plugged with bottle tops pressed into place. The plugs did not need to be restrained because they were protected from direct blasting by replacing the timing chest and cover, although these components were subsequently removed for individual blasting with the gasket faces placed face-down.

Left hand side of crank case with all apertures plugged and blocked. The sump was also retained to protect the inside of the crank case although it was subsequently removed and blasted separately with the gasket surfaces face-down. The engine number stamps were rather indistinct so this area was masked and manually polished later.

Right hand side of crank case with all apertures plugged and blocked. The timing chest was also retained to protect the inside of the crank case and the timing chest covered by the timing cover although these parts were subsequently removed and blasted separately with the gasket surfaces face-down.

The crank case after blasting showing no evidence whatsoever of any ingress of blasting which saved a lot of laborious cleaning work. Nevertheless everything was scrupulously pressure washed, blown out with compressed air and treated with white spot oxidisation inhibitor.