DETROIT (AP) _ Mayor Coleman Young kept out of sight Monday and left the last minute campaigning to his challengers in the city's mayoral primary as he seeks a record fifth term.

Young is expected to lead the field of 13 candidates in Tuesday's non- partisan election. He made no campaign appearances Monday and has voted by absentee ballot.

Neck-and-neck for the No. 2 spot are U.S. Rep. John Conyers, a late entry in the race, and accountant Tom Barrow, whom Young defeated in 1985. All three are Democrats.

The top two finishers advance to the Nov. 7 runoff.

Election officials expect about a third of the city's 507,000 registered voters to cast ballots, a turnout that favors Young.

''Generally, the bigger the turnout the better for an incumbent. But he's the exception,'' Deputy City Clerk Jeff Blaine said of Young. ''I figure the first 50,000 people out (to vote) are his. We know he's going to get his people out.''

Young, 71, the city's first black mayor, was first elected in 1973.

Conyers, 60, picked up the endorsement of the Rev. Jesse Jackson over the weekend, backing he called priceless to his campaign. The 40-year-old Barrow has gathered endorsements from a few city unions and church leaders; the bulk having committed to Young.

On Monday, Conyers greeted workers at a Ford Motor Co. assembly plant in Wixom, 40 miles from the heart of downtown, while Barrow campaigned at the downtown campus of Wayne State University and at a ''Save Our Neighborhoods'' rally at Freedom Baptist Church.

Meanwhile, long-shot Charles Costa, a local businessman, shook hands on a Detroit street corner and knocked on neighborhood doors. City Council President Erma Henderson, also a dark horse, attended meetings with groups endorsing her including a United Auto Workers local.

On Sunday, thousands of Young's supporters gathered for a downtown rally.

A poll released Sunday showed the mayor with more than twice the support of any of his challengers.

Young was backed by 42 percent of Detroit voters surveyed by WJBK-TV and Wayne State's Center for Urban Studies.

The poll, with a 4.7 percent margin of error, found Conyers with 14 percent and Barrow at 12 percent. Of the 427 registered city voters contacted, 25 percent were undecided. The telephone survey was conducted Friday and Saturday.

Two weeks ago, a similar poll found Young's support at 38 percent, Conyers at 12 percent and Barrow at 9 percent.

The National Weather Service predicted cloudy skies Tuesday with the chance of rain late in the day at less than 20 percent.

''In Detroit, most people vote on the way to work or on the way home,'' Blaine said. ''We're looking for turnout in the low 30s (percent of registered voters), which unfortunately is halfway decent for a primary around here. The absentee numbers are pretty good that we've seen.''

Twenty-three percent of registered voters turned out for the last mayoral primary in 1985, Blaine said.