5SFE Getting timing right: Rotating cam and crank shafts independently

[fullofzen]

Before I took off the timing belt, I got the crankshaft and camshaft to their respective positions to get the piston 1 to TDC...however, I at some point ended up rotating one or both of them away from their respective timing marks that in the course of taking off the camshaft sprocket, etc. Oops.

Since the 5SFE is non-interference, is it okay to rotate each of these independently as much as 360 degrees clockwise to get them in the correct positions for TDC? Thanks!

[71Corolla]

Yes.

[fullofzen]

Okay cool. And btw...why is it a bad idea to rotate counter clockwise in the case of either the cam or crank shafts? Can't quite figure out why Haynes warns so highly against.

[1996camry]

highly against rotating the counter-clockwise because your car is rotating in clockwise so the valve closed in right sequences. high against rotating counter clockwise because possible damaged the valves.

[RonR]

Yes this is a non-interference engine so valves and piston can not come in contact even if cam and crank are not in sync.
Rotating the cam counter clockwise is fine if you are just lining up the timing mark and both cams(intake and exhaust) are synced/timed correctly.

Same for crankshaft.

Basic reason they include that warning is that people loosen up the cam sprocket bolt when they turn it counter clockwise and forget to check it when they are done.

[71Corolla]

I think the main reason you are not supposed to turn the camshafts backwards is the irregular shape of the cam lobes. I don't know if rotating the cams in a reverse direction will harm anything or not, but who wants to be the one to find out?

[bolink654]

I've turned engine backwards alot. Including my 5SFE. I've also turned just the cam or just the crank backwards.

On some subarus (edit, maybe it was Volkswagen I'm thinking of?) if you turn the crank backwards with the timing belt on, it may skip. These same engines, when equipped with a manual trans, came with an additional pulley/tensioner to keep this from happening if the engine was left in gear and bumped/parked on a hill in the wrong gear.

I usually take out the spark plugs, and when fine-tuning the timing, I just throw the harmonic balance pulley (or cam pulley if fine tuning the cam) on it and turn it by hand, because when you put the bolt in to turn it, you often move it when trying to take the bolt back out.

[JohnGD]

^ as mentioned, my guess too is that the reason for not rotating it backwards is because it'll mess up the belt tension.

If the belt is off, and 5SFE is a NON-interference engine, you can turn the crank/cam either way just to line things up. Come to think of it I don't think I've turned things backward round and round. Maybe 1/2 to 1 turn at most. I don't know if things develop a wear pattern for example, at least not that I could see.