Possible valve damage
 

This past weekend I replaced the front cam and crankshaft seals on my 01 montero. Also new timing belt. I thought I got everything back together correctly, but after starting the truck, it sounded like top end/ valvetrain noise. The cam timing marks were dead on, but the crankshaft was one tooth behind after taking everything apart again.
I did rotate the cam gears separate from the crank, and it's possible the crank timing mark was lined up. Is that a sure way to bend valves? Also, is how tight should the belt be between the cam gears and water pump, and driver's side cam gear to crank gear? I'm now having trouble keeping all my marks lined up when turning the engine over by hand with the belt and tensioner set.

In the future, whenever possible, do not rotate camshafts separate from crankshaft. However, even if you have done so, setting the timing back to proper marks should take care of it. The key is to make sure you got all the marks lined up correctly. Best way to do this is to look at timing marks using a mirror and follow the ridge of the gear tooth to the marks on the valve heads and on the block. If you just look without aid of a mirror, its easy to get misaligned.

Being off one tooth on timing will not damage the engine and should not result in any noise. You will likely not have proper engine performance and CEL will eventually come on, but nothing more than that. Its easy to correct with re-setting timing to proper marks.

When checking/setting timing, make sure to rotate engine ONLY in clockwise direction. If you go in opposite direction, you can't set timing correctly because timing belt tensioner may compress and show false timing alignment.

Also, you always want to rotate CRANKSHAFT to the timing mark, then check CAMSHAFTS to see of both of those got aligned. If not, move camshafts one tooth in whichever direction they need to go. First align driver side camshaft, then the passenger side. Tension the belt and rotate crankshaft two full rotation again before checking timing.

The tensioner pulley needs to be pre-loaded so that the safety pin in the tensioner rotates completely free and easy. If you have any tension on the pin - you do not have the right pre-load on the pulley.

When you rotate the crankshaft in clockwise direction and properly pre-load the tensioner pulley, your timing belt should have ZERO slack between any components.

Thanks for the tips. I should be able to get it set right on Wednesday morning. Someone mentioned that the valvetrain noise could have been lifters that got bled out rotating the cam gears by themselves. I let it run for a few minutes until it idled down. The noise seemed to be on both heads. Does that sound reasonable?

That is a good point on the VLA bleeding out when camshafts are rotated without oil pressure in the system. Check timing once more to be 100% sure it is correct. Then perform a VLA bleeding procedure as described in the attached page from the FSM.

I got the belt on and tensioned correctly. Quadruple checked all the timing marks after rotatingseveral times with the pin in and out before I put the front end back together. It runs really smooth, but still had the valve train noise. I did the vla rpm/ idle cycling from the service manual. It sounds like 95% of it is gone. Could need more cycles to get the air out of the lash adjusters. Thanks to all for the input.

Now I need to ecm to relearn transmission shifting, seems a little off now.