Chicago Mayor Rahm Emanuel’s proposed changes to the city’s unpopular parking meter privatization deal got a chilly reception from some aldermen at a City Council hearing on Friday, with many concerned the changes would lead to another windfall for the private firm that now controls the meters.

But as he maintained the mayor’s plan would be “a wash” for Chicago Parking Meters LLC, Emanuel’s top lawyer warned that making too many tweaks to the proposal would likely tank it entirely.

Friday’s was the first of three expected hearings on Emanuel’s changes to the contract, which he estimates will ultimately prevent the city from paying more than $1 billion in reimbursement costs to CPM for meters temporarily taken out of commission. Separately, the deal would also allow free Sunday parking in most neighborhoods, in exchange for forcing drivers to feed the meters longer during the rest of the week.

Aldermen questioned why the city couldn’t separate the two components of the deal and vote on them separately, but Corporation Counsel Steve Patton said that would likely sink the deal entirely, after months of negotiations.

“It is part of a package,” Patton said. “It’s not a menu where we can say, you know, ‘Well, we like this and we don’t like that and we like this,’” Patton said, adding that negotiations with CPM would be “back to square one” of aldermen reject the mayor’s deal.

“So I would implore you, don’t ask me to do that,” he said. “‘Cause I can’t guarantee the outcome.”

Despite an invitation from the Finance Committee, officials from the parking meter company didn’t show up to Friday’s hearing.

But Patton’s advice didn’t sit well with aldermen like Pat Dowell, from the 3rd Ward on the South Side.

“I do have problems with some of the other components,” Dowell said. “But I feel like I’m being put in a position to approve this, uh, and didn’t have a role in helping you make that decision.”

Alderman Brendan Reilly, whose 42nd Ward near downtown would see parking meters extended by three hours, until midnight, suggested that aldermen should reject the plan and send Emanuel’s lieutenants back to the bargaining table.

“Well, that’s what’s most troubling,” Reilly said. “We’ve been told this is a take-it-or-leave-it deal.”

Aldermen were wary of any part of Emanuel’s plan that might be a financial boon for CPM, after they hastily approved former Mayor Richard Daley’s initial $1.15 billion privatization plan in just a few days, only to learn later of provisions that would cost the city millions down the road.

Emanuel’s administration has estimated free Sunday parking will cost CPM $8.4 million in lost revenue each year.

But several aldermen questioned the mayor’s estimate that the extended hours would only reap the company $7.4 million a year, asking for more data and a cap on company profits to insure against a windfall. They also wanted guarantees CPM would not be able to share customer data it might obtain through a new pay-by-cellphone option that’s part of the mayor’s deal.

“You’re essentially asking us to place a bet on a deal that benefits the mayor politically,” said Ald. Ameya Pawar of the 47th Ward. “But we have to bear the consequences, and so do the consumers.”

The City Council’s Finance Committee is set to meet for another hearing on the proposed parking meter contract on Tuesday, with a possible committee vote Friday. Emanuel has said he wants his negotiated deal before the full City Council for final passage at next month’s meeting.

Alex Keefe covers politics for WBEZ. Follow him @akeefe