Mitsubishi Repair: 1993 3000gt engine, gm man, vacuum leak

Question
i know you get a lot of questions, but if you could help me out i would greatly appreciate it....i'm an ase certified tech in 4 areas, but a GM man! i have a 1993 mit. 3000gt and i just replced the timing belt and water pump( yes, a ecu also) and it has started making a top end noise, front right(looking at the motor) this problem has occured slowly, i did not replace the tensioner, could this be the problem?  starts making noise about 2500 rpm and will not idle, like a vacuum leak.....any feedback would be appreciated....thank you   -Ryan

Answer
Ryan,
I have run into this problem with an Eclipse after a timing belt change had been performed.  And yes, it was a tensioner problem.  Since then, I've never replaced a timing belt without replacing the tensioner as well.  I've even seen this happen on Hondas.  Replacing that tensioner is pretty critical.  I believe the cost for a 3000GT is about $100 from the dealership.  Give it a shot, and install a new tensioner.  Hopefully that will fix your problem, but if not, you'll have piece of mind that your old tensioner won't fail completely and cause even worse problems down the line.
Good luck!