a/n: Rey is a Mechanical Engineering major, taking a class and practical lab for repairing/designing diesel engines. Luke is the prof.

“Now the most important thing is to keep track of the components. I can’t tell you how many times I wound up with ‘spare parts’ after reassembly.”
A few of the students giggled. Rey just rolled up the sleeves of her grease-spotted coveralls and leaned closer, sighing as her hips pressed against the vibrating engine block. Luke’s stomach flipped as their eyes met…and then darted away, an expression of polite attention on her face.
“Well,” he said, straightening. “To state the obvious, before we can take a look inside, we need to shut the engine down.” There were more giggles. Luke smiled and gestured at Jessica, who was inching towards the kill switch in what she clearly thought was a subtle manner. “Jessica, if you please?”
The twelve students watched attentively as he walked the third-year engineering student through the shutdown process. It was the first lab, and since most of the students in Diesels 1 had never changed their own wiper fluid, much less disassembled a 6-cylinder Caterpillar engine, he figured he should start with the basics. Soon the engine lurched to a halt. He smiled thankfully at Jessica and had Snap set up the chainfall.
“Today we will be removing the fuel injectors and changing the oil,” he said. “I hope you all brought your toolboxes?” Most of the class nodded. “Excellent. Now, please divide into teams – three to an engine. The instructions are on page 8 of your lab manual. Mr. Dameron and I will be observing. Please do not hesitate if you have a question or require assistance. You have until 2:00. Now get to it!” He clapped his hands and gestured at the four engines set up around the lab.
“It’s a good bunch this year,” said Poe Dameron, a Ph. D candidate and the lab TA. “The demographic’s certainly changed since I was in undergrad. I wonder why?” He shot Luke a sly glance.
“You certainly haven’t changed,” said Luke, in a tone that meant ‘you are so full of it’.
…Though Poe did have a point. 8 out of the 12 students in the lab were girls.
“You know there’s a waiting list for this time slot…” Poe continued. Luke rolled his eyes.
“Shouldn’t you be helping someone?”
Poe cracked his very best shit-eating grin.
“You know, Finn over there looks like he needs some help with that torque wrench…”
He mussed his dark hair and sidled over to where the tall, black man was fumbling with said wrench, trying to set it to the correct value, and glancing up at Poe with wide, hopeful eyes. Luke suppressed a grin.
“Professor Skywalker?”
Luke jumped. Rey was standing close enough that he could see the sweat beading on her forehead, and her rosy, blushing cheeks. Well, it is hot in here… he thought, steadying himself.
“What can I do for you Rey?” he asked, taking a careful step back.
“We’re having some issues…” she said, leading him over to her station. Rey, Jessica, and Bea (who went by BB) were clustered around their engine, a green V-4. They’d gotten the cover off and exposed the cylinder heads and fuel injectors, but had so far been unsuccessful with their removal attempts.
“It’s just here,” said Rey, tracing greasy finger over the insertion point. “We detached all the lines, but…it’s just in so deep. Like it doesn’t want to come out.”
“Ok,” said Luke. “Pass me the oil please. And that rag.”
BB and Jessica exchanged a quick, (and rather unnecessarily smirky, in his opinion) look and passed him the items.
“Now sometimes you just have to give it a little extra lubrication, like this,” he said, dripping oil around the head. “Hmm,” he frowned, his long fingers carefully circling the area, oblivious to the fact that he had the three girls’ undivided attention. “The fit is a bit tight…Now, give it a pull…” Rey reached in and tugged gently, to no effect.
“Eh, still nothing,” she said. “Maybe if you – “
“Ok, you hold here and I’ll twist here – there, now try it.” Rey leaned in, their faces so close they were almost touching. Her breath was warm and light on his cheek.
“Like this?” she murmered, twisting it to the left, her fingers slippery and hot against his.
“Eh, maybe…This?” Luke gulped and focused resolutely on the injector. “Ok, now!”
“Ah…” gasped Rey as the injector slipped out. “Now that’s better.” Jessica snorted.
“That’s wha-“
“Don’t. Just don’t,” BB muttered. Jessica smacked her in the arm.
“Uhm, yes. Great!” said Luke, a little too loudly. Rey smiled proudly, cradling the dripping, tapered cylinder in her hand. BB tossed Rey the cloth with a happy giggle.
“Thank you Professor!” said Rey. “I’ll just clean this up and we’ll change the oil.”
“Dibs!” said Jessica, grabbing a screwdriver and crouching down near the oil reservoir. BB pouted and started arranging the removed nuts and bolts in proper replacement order. Rey held the injector carefully and ran the cloth up and down it’s smooth length. Once she’d removed the worst clogs, she got a fresh cloth and encircled it, moving her hand slowly up and down. Then her eyes flicked to his. Luke felt his throat run dry as he realized he’d been staring. She held his gaze and bit her lower lip, smoothed it over with her tongue. She lifted the injector until it was level with her chest, grasped the larger end, and started pumping it rhythmically, breathing in and out with each stroke, giving the end a little twist before she slid back up…
“Professor? Sir!”
“What?” Luke jumped. Snap waved him over, gesticulating franticly with a broken screwdriver. Luke sighed and came back to earth. Looks like it was the first re-drill of the semester…

a/n 2: This is a fuel injector: http://pawlikautomotive.com/wp-content/uploads/2012/04/cummins-injectors.jpg