This may not be caused by endogamy. I have a personal case where a known (by paper trail) 2C2R matches me with 236 cM total. This is way beyond the expected amount and is due not to endogamy. Her Great Grandmother was my father's cousin. The rest of her relatives going down that line were non-Jewish, so endogamy does not come into play, nor inheritance through a second line.
When you inherit DNA from a set of great grandparents, you do not always get an even split between the two. And you may continue to inherit that larger amount going further. It does not always get diluted by halves in each generation. This is what happened in my case. My match maintained more of that specific multi-great grandparent's sequences that would be expected.
Another example is my wife who shares an untouched 48 cM segment on a particular chromosome with relatives who are known 6Cs. Some chromosomal sequences continue unaltered.
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Bob Smiley
Kirkland, Washington USA