What is the relation between crankshaft and camshaft?
A camshaft uses egg-shaped “cams” to open and close engine valves (one cam per valve), while a crankshaft converts “cranks” (the up/down motion of the pistons) to rotational motion.
What is the purpose of crankshaft camshaft timing?
The camshaft is connected via the timing chain and sprockets at a 1:2 ratio to the crankshaft and therefore revolves once for every two turns of the crank. Its purpose is to operate the intake and exhaust valves in the correct timing with the piston as it sequences thru the four strokes.
When to replace the timing belt and crankshaft?
On most cars it is normal to inspect the front crankshaft and camshaft seals while replacing the timing belt. When you have the front of the engine apart they’re right there but generally neither are particularly easy to remove.
Can a camshaft be turned without a belt?
However, both camshafts need to be lined up with the timing marks as well as the crankshaft turned to TDC before you install the belt to keep everything lined up correctly. My belt guide also shows this not to be an interference engine, so the cam shafts and crankshafts can be turned independently without causing damage.
Where are the timing marks on the crankshaft?
The mark on the camshaft sprocket should be aligned with the mark on the inner timing belt cover or the edge of the cylinder head. With the distributor cap removed, the rotor should be pointing toward the No. 1 mark on the rim of the distributor housing.
When to set the cams on a crankshaft?
I would suggest at this point in time that you start with the crankshaft at 30° before top dead center and set the cams. At this point, there will be plenty of clearance for valve in every cylinder. When the cams are in position, then rotate the crankshaft to TDC and install the belt.
Why do you need to lock down the timing belt?
Even though belts will not last as long as a chain, they are quieter and often easier to line up correctly with the cam and crank locked down. Anytime the belt is removed, the cam and crank need to be aligned to TDC No.1, which is where the marks on the crankshaft pulley line up with the pointer on the front cover.
What happens when you have a camshaft timing error?
When a cam timing error slithers in, it can arrive from either of two directions: A cam drive either wears and becomes loose and jumps a tooth or more, or it completely breaks. In either case, camshaft timing often rattles a death song and the engine quits. Approach a timing problem with caution.
Do you have to be dead on with timing belt alignment?
Because modern vehicles use so many electronics to control the engine with things such as crank and camshaft timing sensors, technicians need to be, as we say in the industry, “dead-on” with the timing belt alignment. The cam gear cannot be off by even a tooth, or the engine will set a DTC.
Why do I need to check the timing on my engine?
Valves may already be biting into the pistons and you may cause more damage. Should the engine turn freely by hand and you have easy access, position the crank and check the timing marks on the crankshaft and cam.