International banking problems have kept some top Treasury officials on the road and in the air lately.

Deputy Secretary Tim Mc-Namar, expected back by the end of the week, has been with a congressional group touring troubled debtor nations in Latin America, including Peru, Mexico and Brazil. McNamar also visited Argentina.

All these countries owe a lot of money to U.S. banks and are now following economic programs arranged through the International Monetary Fund. Dennis Thomas, assistant secretary for congressional relations, and Tom Dawson, deputy assistant secretary for developing nations, also were on the trip.

Officially it was described as an opportunity for the U.S. officials to meet with leaders and businessmen in the Latin nations to examine their financial problems and ways to solve them. Privately, officials described it as a "sales trip" to encourage support for President Reagan's legislation to increase IMF resources.

The bill is now going through Congress and is widely expected to pass despite congressional uneasiness.

Treasury Secretary Donald T. Regan, who arranged the whole thing and initially planned to go along, pulled out because of pressing business at home, including new economic forecasts and budget battles on Capitol Hill. The new forecasts, released last week, went part way toward correcting what Treasury officials thought was too much pessimism in the original forecast.

Regan is expected to find time to go down to Mexico with Secretary of State George P. Shultz this month for discussions about what the State Department calls "our myriad economic and financial ties" with Mexico. Treasury officials say Shultz asked Regan to accompany him on the April 18-19 visit.

New money for Mexico is bound to be on the agenda. Senior bankers estimate that declining oil prices could prompt Mexico to request $1.5 billion to $2.5 billion of extra money from its creditors this year. NEW FACES . . . Carole Dineen, formerly of Bankers Trust, is the new fiscal assistant secretary in charge of overseeing the government's financial operations, with responsibility also for cash management and managing the public debt.

Other changes: Jacob Dreyer, who was second in command to Denis Karnosky in the Office of Monetary Policy Analysis under monetarist Beryl Sprinkel, has moved over to the Office of Economic Analysis under Manley Johnson. Karnosky departed for Chicago some weeks ago, and neither he nor Dreyer has been replaced. Dreyer, who has concentrated on studying how the rest of the world affects the domestic economy, is acting as one of the two deputies to assistant secretary Johnson.