The Bolivian Army today toppled the president that it had helped palce in power four months ago, and promised elections next year. It was the 184th coup for the landlocked South American nation in 153 years of independence.

Army commander Gen. David Padilla Arancibia led the bloodless takeover and said he would serve as provisional president until elections July 1, then turn over power on Aug. 6, Bolivia's national day.

Padilla, 52 ousted Juan Pereda, an air force general who seized power with army help in July after cancellation of elections that he claimed to have won.

Those elections climaxed an intensive effort by the Carter administration to foster a return to constitutional rule by the many military governments in Latin America.

The elections ended the rule of another general, Hugo Banzer, whose seven years in the Palacio Quenmado - "burned palace" - was a modern-era record for longevity in Bolivia. The palace takes its name from a coup years ago. In front of it is another landmark: a lamp post from which a deposed president was hung.

Banzer had chosen Gen. Pareda as the military's favorite in the July elections, running against a former president who served during Bolivia's 1950s era of revolution and relatively democratic rule.

That former president, Hernan Siles Zuazo, ran strongly in the voting despite evidence of massive fraud in favor of Gen. Pareda. The electoral court canceled the results and Pereda seized power, blocking U.S. efforts to establish a precedent here for the neighboring military governments of Argentina, Chile and Brazil, Peru next door, is in the process of returning to civil rule.

Siles Zuazo welcomed today's coup and the accompanying promise of prompts elections but said his center-left coalition would remain vigilant.

Pereda, 47, had promised elections in 1980, apparently too late for the current mood of the military. Next year is the 100th anniversary of the start of the War of the Pacific in which Chile captured Bolivia's territory on the Pacific coast.

All Bolivian leaders, civilian or military, call for recovery of the outlet to the sea and the army has called for national unity to accomplish that next year.

Bolivia's 6 million population is mostly Indian and one of Latin America's poorest. The price of the main export, tin, has fluctuated widely and the miners' high production costs put the country at a competitive disadvantage.

According to unconfirmed reports, Pereda flew from this mountain capital to his personal power base in the lowland eastern city of Santa Cruz after the army takeover.