View Full Version : what causes a jump in timing?

01-29-2006, 05:40 PM
i just got my celica running after an engine swap. i cranked it and let it run and it seemed to idle a little rough so i kinda concluded that my timing was a little off. but by the time i got back with a light and tach i started the car and it just died. no backfire or anything and it wouldn't fire up again.after a lot of research i pulled the dist.cap and decided to see if it lined up on tdc with tension wire one and they will not line up. i think this tells me my timing is off. i'm going to pull the timing cover today and see if the crank and cam are both at tdc for cyl 1.i will inspect the belt but how can i really determine if the belt is too worn.i would love some advice on why jumps in timing occur.could reving it with the timing a little off cause a more serious jump somehow or is my belt just worn.according to whom i bought the motor from it only has 35,000 miles on it. certainly not enough to have a worn timing belt without a more serious cause.

01-29-2006, 10:42 PM
its probably a worn belt or tentioner. milage is not the only thing u have to consider. age will wear the belt just as badly.

Midnight 2
01-29-2006, 10:43 PM
I had a similar problem with an old Pontiac Sunbird. The timing belt was worn and under certain loads if the belt is worn enough it can jump teeth obviously advancing your timing or retarding it.

You are correct in thinking 35,000 miles not being enough for a worn timing belt... Just take into consideration how long the car was sitting.

01-29-2006, 11:17 PM
yeah, you should always replace all the belts with an engine swap anyway. After all you wouldn't run it without changing the fluids...

01-29-2006, 11:24 PM
skipped tooth