Both Carlisle and Southend created chances in an entertaining fixture at Brunton Park which brought two goals in two minutes just ahead of the break.
A thundering cross from Symington brought early applause from the crowd as Bentley struggled to deal with just beneath his bar. He got two hands to it but Bolger was needed to complete the clearance.
The visitors created space when they kept the ball in the midfield areas and Coulthirst stepped forward when he spotted an opening for an overlap. He had options and his shot from 25 yards was weak and always heading wide.
A Carlisle corner caused problems as Potts battled for it on the edge of the area with the action flowing from end to end. Leonard moved across to hook it away as the blue shirts flooded the box in search of scraps.
The Cumbrians had a good chance to open the scoring on 10 minutes when a long kick forward from Gillespie was flicked on by Paynter. Sweeney tried to control it and his touch left Marriott with a difficult chance at a tight angle. He had to lift it and he put too much on the shot as it angled over the bar.
United went close again moments later when Paynter pulled wide to deliver a low near post cross. Marriott arrived at pace but he was under pressure and his volley rattled into the side netting.
Southend came into it midway through the half and a long throw was glanced on by Corr with plenty of yellow shirts in attendance. It bobbled through to defender John White and he sent a powerful drive wide of the target.
Marriott twice had shots blocked as Carlisle passed the ball well and the visitors went close again at the other end when Dicker was robbed of possession in midfield by Coulthirst. Weston pulled free, beat O'Hanlon and then wasted the moment with a shot which was never going to trouble the keeper.
Centre forward Barry Corr showed fantastic technique when a dipping pass from Weston invited a volley on the run. He kept his eye on it and Gillespie had to be alert to prevent the top corner bound rasper from finding the roof of his net.
Southend had a good spell and O'Hanlon stopped Weston in his tracks as he skipped through two challenges with the ball at his feet. Carlisle eased the pressure with some good movement from Sweeney and Paynter which left Brough with time to cross. Marriott won the header but it bounced wide with the keeper beaten.
United were on top and they made it count when skill from Potts brought men forward in support. Brough was released and his perfect cross found Antony Sweeney who made no mistake with a crunching header which Bentley could do nothing about.
But the home lead was wiped out on the stroke of half time when Clifford picked the ball up 40 yards from goal. His grasscutter whistled through bodies and the unsighted Mark Gillespie could do nothing as it popped into his bottom corner.
A measured United build up which involved Potts, Brough, Paynter and Dicker announced the home intentions with just two minutes on the second half clock. Symington got it and cut back before unleashing a powerful left foot shot. Bentley could only parry it but the danger was quickly cleared.
Marriott was unlucky as the blue shirts stayed forward for a corner when his touch left Bentley flapping at thin air. He was ready to celebrate but it bounced agonisingly wide.
It was all Carlisle and a slide rule pass from Paynter left Marriott with a clear run at goal. He shot early, from 19 yards, but Bentley was well positioned to save it.
A huge kick forward put Southend on the front foot and Coulthirst twisted and turned as he battled for it with Thirlwell. The experienced captain won the day as he blocked the shot on the stretch.
The game was finely balanced and Symington beat two before finding Potts on the edge of the box. He took a touch but he lifted his clipped shot over the bar.
The Shrimpers reorganised and started to look dangerous and Grainger had to hook the ball away as a Coulthirst header threatened to creep in. And the same player put a shot on a plate for Leonard when he pulled the back but Gillespie did well to drop low and palm it away. The big stopper had to recover quickly to prevent the lively wide man from finishing it off.
Another huge ball forward caused problems for United as it bounced short of the 18 yard box. Gillespie had to head it and Barnard wasted no time in sweeping it back at the empty goal. Worrall touched it on but O'Hanlon did well to hold his balance and lob it away.
Weston was wild when a deep cross fell at his feet with Southend pushing on, and Carlisle went close when Elliott looped a header just under the bar for Bentley to catch.
Gillespie was busy through the closing stages, with saves from Worrall and Barnard required, and Carlisle swung balls into the box as they searched for the goal to earn them the win.
But it was honours even come full time as United made it two games undefeated from a tough week of League Two football.
United - Sweeney (43)
Southend - Clifford (45)
Southend - White (52)
Carlisle United - Gillespie, O’Hanlon, Thirlwell, Grainger, Symington, Brough, Dicker (Dempsey 70), Potts, Sweeney, Marriott (Elliott 70), Paynter. Subs - Hanford, Amoo, Gillies, Rigg, Douglas.
Southend United - Bentley, White, Coker, Prosser, Corr (Barnard 76), Weston, Hurst (Atkinson 64), Bolger, Clifford, Coulthirst (Worrall 64), Leonard. Subs - Ibenfeldt, Thompson, Payne, Smith.
Referee - Mr Chris Kavanagh
Attendance - 3,847 (269 away fans)