* Interference: The most serious possibility is that the timing belt was installed incorrectly and the valves have hit the pistons. This is a common problem when the timing is significantly off. If this has happened, you'll likely need a major engine repair, possibly involving replacing bent valves or even damaged pistons. You won't be able to simply turn the camshaft.
* Bent valves: Even if the pistons and valves didn't make direct contact, the timing being severely off *could* have bent valves. The engine's resistance you're feeling is a strong indicator of this possibility.
* Seized component: A seized component within the engine (e.g., a connecting rod bearing, piston, etc.) can prevent the camshaft from turning freely.
* Timing belt tensioner or other belt components: If the tensioner is broken or the timing belt is jammed, it would prevent normal camshaft rotation. Check that the tensioner is functioning correctly and that there is no binding or damage to the belt.
* Incorrect installation of camshaft gear or other timing components: It's possible the camshaft gear is incorrectly seated, or another timing component is installed incorrectly, leading to the obstruction. Double-check all timing marks and the installation procedure.
What you should do:
1. Do NOT force it: Trying to force the camshaft will likely cause further damage.
2. Remove the timing belt again: Carefully remove the timing belt to confirm its correct installation and check the tensioner. Inspect the belt for any damage.
3. Inspect the valves and pistons: If possible, check the valve clearance and inspect the pistons for damage. This usually requires removing the valve cover and potentially the cylinder head. This step often requires specialized tools and knowledge.
4. Inspect other engine components: If you find no obvious valve or piston damage, check other components for seizure.
5. Seek professional help: Unless you have significant mechanical experience, it's strongly recommended to take your vehicle to a qualified mechanic. Attempting to repair this yourself could result in very expensive damage. The initial cost of diagnosis and repair will almost certainly be less than the cost of extensive engine work if you continue to attempt repairs yourself.
The resistance you're encountering is a serious warning sign. Don't ignore it; addressing the problem promptly will minimize the damage and cost of repairs.
