Both sides had second-half chances and Motherwell had a goal disallowed before the game ended in acrimonious fashion with Hearts wing-back Jake Mulraney sent off for apparently swearing at the referee in the 90th minute.
Motherwell moved back into third place in the table following a third consecutive win and clean sheet while St Mirren jumped above Hearts, who are in a group of three teams on 12 points at the foot of the table.
Hearts are hoping to appoint Stendel in the coming days after protracted negotiations involving Barnsley, who have been seeking compensation for the manager they removed from his post two months ago, and he faces a challenge to get their confidence back up.
There was precious little goalmouth action until the goal. Hearts were lively at the start but were gradually forced back without being cut open by the hosts, who named an unchanged team despite being hit by a bug.
Hylton continued to look dangerous and had a shot deflected wide as Motherwell started the second half with purpose.
Hearts finally got going as an attacking force about 12 minutes into the half with Ryotaro Meshino twice getting shots away, the first volleyed over from 18 yards after Halkett's knockdown and the second from further out giving Mark Gillespie a comfortable first save of the game.
Uche Ikpeazu had come on in between to add some physical presence to the Hearts attack but the visitors' best chance came after Motherwell centre-back Bevis Mugabi lost possession after bursting into the opposition half.
Hearts quickly worked the ball into the vacant space but Gillespie got down well to stop Steven MacLean's shot from the edge of the box.
The Edinburgh side soon had a let-off when Motherwell had a goal ruled out for offside, perhaps needlessly, following a counter-attack.
The visitors had chances – Jamie Brandon blasted wide and Ikpeazu curled not far off target from 18 yards.
But they could not mount any sustained pressure in the closing stages and Mulraney vented his frustration as Motherwell played down the clock with referee Alan Muir showing a straight red card.