Car guys i need your help with timing belt problem.

i got my truck (1986 Isuzu P'UP 2.3L with spacecab) back together and running but the timing belt wants to slid off the front of the cam, oil pump and ideal pully the 2 spacers are on the crank pully and is fine on it but the belt wants to come off the rest of the pullies. http://www.isuzupup.com/images/smiles/icon_eek.gif what might be causing this? http://www.isuzupup.com/images/smiles/icon_question.gif

 

How's the bearing in the tensioner pulley?

 

Is it slipping off once you crank it over? (immediately or does it run for a while)
My best guess is either misalignment from one pulley to the other, or if you have a tensioning wheel it may have slipped or bad bearings in it. I am assuming belt is new and correct type.

Had a problem 2 months ago with a ford van at work that would go through power steering belt about every 2 months...turns out the shop mechanic forgot to put a spacer behind PS pump b4 mounting it ....rolleyes The difference was very hard to spot visually



that might of helped

 

Is it a new tensioner as well ? I changed a timing belt on a BMW last year, and the new tensioner that came with it was slightly warped. I only noticed when I bolted it onto the engine and spun it with my fingers. It was slightly out of true and I refitted the old one rather than risk it.
Or maybe the belt is defective. It's quite rare for new parts to give trouble straight away but not completely unheard of.

 

Run a straight edge across all the pulleys if you have enough room, but generally alignment isn't an issue with timing pulleys. Also see if there is any play in any of the pulleys with the belt off. If the cam pulley for example is cocking slightly with the tension of the belt on it, the belt will pull itself off. One other thing, on some Fords I work on, there can be two different belts for the same engine, one with square cut teeth, or round cut teeth.

 

sound advice.
does that motor run the water pump off the timing belt? I'd check the bearings there if it does.
Not too familiar with that engine.

 

What have removed and replaced,have you had the head off?