The U's picked up a valuable point on the road at Vale Park, after Luke Norris equalised for Steve Ball's travelling side after Devante Rodney had put the hosts ahead just after half time.
Steve Ball made two changes to his starting eleven at Vale Park from the side that grabbed an important three pointst at Scunthorpe in the week.
Kwame Poku and Ben Stevenson returned to a starting berth, with Luke Gambin and Courtney Senior sitting on the bench.
The U's looked to make a fast start at the empty Vale Park, and won themselves a corner in the opening thirty second when Harriott and Bramall combined well down the left flank. The ball was cleared to Chilvers from the corner, who saw his shot fly just wide of Brown's post in the first minute.
But Vale also wanted to get an early goal, and almost had it from the right boot of Alex Hurst. The wide man was found unmarked in the centre of the area, but could only curl his effort wide of Gerken's left post - a let off for the U's in the early stages.
The U's 'keeper was called into action shortly after, as he got across well to his left. Tom Conlon's free kick was heading for the corner of the net, but Gerken pushed the ball around the post before the U's were able to clear.
The home side were asking all the questions of the U's defence, but it was a Colchester forward that put in the best stop so far. Luke Norris was in the right place at the right time to block Emmanuel Oyeleke's powerful volley, blocking the ball on the line.
With twenty minutes played, Steve Ball's side forced a save out of Scott Brown. Jevani Brown neatly found Callum Harriott on the edge of the area, who looked to shoot only for his curling effort to be palmed away by the home 'keeper.
For the remainder of the half, there were no real clear cut chances for either side. Vale were often threatening of Gerken's goal without actually testing the U's 'keeper, while there were limited chances up front for Brown and Norris.
The teams headed for the dressing rooms goalless with room for improvement on both sides in the second half.
Just a minute into the second period, the home side thought they had found the breakthrough as Mills slid the ball beyond Gerken, only to be flagged for offside. Rodney burst through the middle before the ball squirmed out to Mills who colly beat the U's 'keeper only for his goal to be disallowed.
The travelling side didn't have their spirits dampened by that scare and nearly found the opener themselves. Callum Harriott found Norris who powered his way forwards and curled an effort just wide of Brown's far post.
But it was the home side that did get their noses in front twelve minutes into the second half. Devante Rodney was the man who found the net, after driving forward and unleashing an untoppable effort into the bottom right corner of the net.
The home side wouldn't be able to hold their lead for long though, as the U's equalised seven minutes later through Luke Norris. Ben Stevenson spotted the run of Norris who took the ball to a tight angle before blasting it under Brown to make it 1-1.
Vale rallied again and looked to get their noses in front, but like in the first half really struggled to test Gerken for the final twenty minutes of the half.
Luke Norris went close to snatching all three points in stoppage time when he turned and shot towards the near post, with Brown parrying and palming away the follow up from Michael Folivi.
The U's remain in the play-off places after the full time results around the country, taking their points tally to twenty-eight from seventeen games.
Sitting in sixth position, Steve Ball's side will travel to Cambridge United on Tuesday night, who themselves have fallen out of the top seven after a strong start, now sitting ninth after their most recent game, a 2-0 defeat on the road to Forest Green Rovers.
Port Vale starting XI: Brown, Joyce (Pope 77'), Legge, Smith, Worrall (McKirdy 74'), Oyeleke, Conlon, Mills, Rodney, Fitzpatrick, Hurst.
Unused subs: Robinson, Brisley, Clark, Burgess, Visser.
Colchester United starting XI: Gerken, Welch-Hayes, Bramall, Smith, Norris, Brown (Folivi 62'), Harriott (Sowunmi 90'), Chilvers (Gambin 62'), Eastman, Poku (Senior 62'), Stevenson.
Unused subs: George, Clampin, Tchamadeu,