I think Argentina was gutted in the 1880s (only a slight difference, but it makes the War of the Pacific more interesting when the Chilean Navy attempts to help its 'enemy' against a foreign invasion. Local problems are one thing, but empires looking to make new dominions on what you might look on as your soil is another).
This shift in power in South America averted the Civil War, and since even if the new president was "Chile for Chileans" the Americans would be more behind Chile (against the British and South Africans) as it stood to keep the Old World out of the Western Hemisphere as best it could. The 'Baltimore Affair' might have still happened, but without the switch in govenment during the Civil War, the war scare would likely not have happened.
However, in the 1890s or early part of the 1900s Chile had to have started getting naval aid from both Britian and Nordmark. Probably by seeing the weakening of Argentian as a bonus without gaining support from the South Africa invaders directly, as they would still be considered a threat during that generation.