And the ABYC section I mentioned earlier does address them specifically for gasoline engines. The stretch into diesel engines, however, is only made by those interpreting the recommendation by applying it to all engines on a boat, not ABYC itself.

Again, the ABYC stuff are only recommendations, and only for US boats. Some of their recommendations could be considered downright dangerous - particularly some of their electrical standards, which are in complete opposition to the recommendations from other standards bodies around the world. I purposely go against several of the ABYC standards because they are illogical or wrong. This isn't the bible or law books we are talking about here.

As for surveyors and insurance, we have 3 diesel engines on board with a combined 4 non-shielded racors in their engine rooms. We have used 5 different insurance companies and 5 different surveyors and none have ever asked or specified heat-shielded filters. The secondary filter on our Kubota-based generator itself consists of a small plastic bowl that has no way to put a heat shield on it. This generator is sold solely as a marine generator to be used in an enclosure (it comes in a tight enclosure).

So, yes, a particular surveyor or insurance company may require shielded filters because of some personal reasons, but I would simply let my money talk and get another surveyor or insurance company.

Of course, adding those shields is easy enough, but Racor/Parker gouges you for $50-70 each! I won't buy one on principle!

Mark