How much can a crankshaft turn?
You can turn a crank as far as you want… as long as you can find bearings. They used to make a lot of bearings as far under as 0.050″ and 0.060″ or more.
Can you bend valves by turning camshaft by hand?
Registered. Yes, I manually rotated a crank years ago after lining up cam gear marks to center valve cover arrows. Resulted in bent front intake valves and once the starter got involved, a valve snapped off and locked against the piston. Moral: Some FSM diagrams are misleading, and it’s possible to bend valves by hand.
How do you tell if a crank needs to be turned?
Generally speaking, if the crank shows less than 0.001-inch runout, it’s probably fine. If the crank shows more than 0.001-inch runout, it needs to be either straightened or replaced. Crank straightening is a precision task that should only be handled by a skilled specialist.
Is it easy to bend a valve?
In many engines, it is possible for the pistons to contact the valves if the engine’s cam timing is incorrect. If the timing belt or timing chain is replaced but the engine is not timed correctly, it is very easy to bend a valve on an interference engine.
Can a starter bend valves?
Yes the starter is strong enough to bend valves and if the crank is turning and not the pulley, then yes the piston will hit the valves. Pistons are moving up and down and valves are stationary. More damage is done in an interference engine by trying to restart it when a timing belt breaks.
What happens to the crank when the shaft bends?
When the shaft bends, it’s the crank web that is actually deflecting, so most of the stress is concentrated on the fillets on both sides of the rod journal. That’s why the crank usually breaks in the fillet radius if it’s overloaded and bent too far too often.
What to do if your engine has a bent valve?
Turn the engine over by hand a couple of times to make sure no internal components are contacting before you button everything back up. If the timing belt were to snap on an interference engine, there is a very good chance that a piston will contact a valve and bend that valve.
Can a broken timing belt cause bent valves?
Interference vs. non-interference engines. The level of damage caused by a broken timing belt can depend on the type of engine you have in your car. A non-interference engine provides clearance between the valves and pistons, so if the timing belt breaks, you might end up with bent valves, and you might have to have your cylinder heads rebuilt,…
What makes a valve bend on a non interference engine?
A non interference engine is an engine design that has the valves and pistons spaced far enough away from each other that there is no possible way for them to contact, regardless of the timing. If the timing belt or timing chain is replaced but the engine is not timed correctly, it is very easy to bend a valve on an interference engine.