Jim Grant's Tech Tips
`89 Jetta timing belt
Is it true that when the timing belt goes out on an ’89 VW Jetta 1.8 16v engine it’s necessary to do a valve job because the valves get warped do to the stress on the engine?
Warped due to stress, I wouldn’t word it that way. It is more like the valves got bent because the pistons beat the daylights out of them. Basically, there are 2 engine designs in this world; 1. The interference engine. 2. The free running engine. Your engine is known as choice #1 The interference, bang and bend engine. The job of the timing belt is to open and close the intake and exhaust valves in the correct relationship to piston movement. When the timing belt fails to maintain this critical relationship, a piston can be heading up while a valve is still open. When this piston to valve collision occurs something has to give. If you’re lucky, it’s the just valve/valves that get bent, if you’re unlucky the valve/valves get bent and the piston or pistons break too. I’ve seen it happen all 3 ways. Oh yes, the third way! This is when you’re a really lucky person and nothing gets bent. For those of you that have the free running engine design, that free running thing is not a guarantee. All it takes is that common carbon build-up on the pistons and valves to take away that precious clearance that turns a free runner in to a colossal collision interference type motor. That is why timing belt maintenance isn’t an expense it’s a money saver.