Tweet
after TB replacement, belt vibrates REAL bad
Hi, last year I replaced a timing belt in my 91 3.4 DOHC and I have been having problems with it ever since. Just recently I broke it out of winter storage to try and figure out this headache again. First some background, it’s in an 86 fiero that I have driven for about 10k miles. The engine has about 15k miles since it was rebuilt, bored, internals balanced, heads refurbished with mild polishing, etc. Last year the TB blew out at about 5k rpm going onto the highway. I replaced it, timed it, did the whole job correctly to the books, the only differences are that I installed 94-95 cam cogs for easier adjustment, and re-used all the pulleys since they only had 15k on them. then I started it and it vibrated REALLY bad, it sounds like its grinding at 3k rpm (can easily hear it in the cab from 2500-4000 rpm, but 3k is the worst)... but its not grinding, its basically like how a guitar string put out sound except on a timing belt. At first I thought the belt wasn’t tight enough so I rebuilt the tensioner, tried it again, same thing. So I increased the spring pressure on the tensioner... probably doubled the pressure forcing the arm out. Put it in, and the same thing happened. And the last thing I did last year was bought another stock tensioner and put it in, then just drove the car for a last test drive before winter and the TB jumped a link at the crank shaft so I towed it home. I just re-timed it after I got it out of cold storage and the problem hasn’t changed so that’s where I am now...
I am getting to the point where I am starting to strip threads on the intake and valve covers because I have taken the off and put them back on so many times, ANY help is appreciated, I would like to get this problem resolved soon. Thanks in advance guys.
Has anyone ever had this bad vibration before?
How tight should the belt be? (At the belt, not the tensioner pulley, how can I test it?)
These are non-interface motors, but is there ANY way to mess up the drive train on them with timing belt blowing or bad timing?
Could it have anything to do with the newer style cam cogs?
Can it be some sort of harmonic imbalance? If so where can it be coming from?
Anything else?
I am getting to the point where I am starting to strip threads on the intake and valve covers because I have taken the off and put them back on so many times, ANY help is appreciated, I would like to get this problem resolved soon. Thanks in advance guys.
Has anyone ever had this bad vibration before?
How tight should the belt be? (At the belt, not the tensioner pulley, how can I test it?)
These are non-interface motors, but is there ANY way to mess up the drive train on them with timing belt blowing or bad timing?
Could it have anything to do with the newer style cam cogs?
Can it be some sort of harmonic imbalance? If so where can it be coming from?
Anything else?