OM603 - which way is engine rotation ?
 

Hi there everyone - I feel dumb asking this, but I am taking the head off my 300TD, I don't remember exactly which way the engine turns. I need to set the cam to TDC on cyl #1. The FSM only says to turn the engine in it's direction of rotation (so vague). I looked at the fan blades, it looks like, standing in front of the car, looking at the engine, the engine turns clockwise. I don't want to crank this backwards.

Thanks !

Most all (with noted exceptions) engines rotate clockwise...

Thank you ! That what I thought, but needed to confirm.

It is CW if you are facing the engine. You can tell also by spinning the engine using the starter motor - tie down the shut off valve if you do NOT want the engine to start.

You can turn the engine whichever way you want, it is not going to jump a teeth on the OM603. It is physically impossible for the timing chain to jump a teeth if turned backwards ( CCW ) as the TC is restricted in 2 places, near the IP and the oil chain.

Virtually all engines turn counterclockwise when viewed from the power take-off end of the engine. The exceptions are chain saws, paired marine engines, and some older English cars IIRC.

Most all turn CW when viewed from the front, looking aft, i.e. if you tighten the crankshaft bolt, you will rotate the engine in the correct direction. The main exception I know (recall) is some 60-70's Ford Lincoln engines. Easiest way to tell is look at an engine-driven fan blade. All should pull air thru the radiator.

Looking at the fan blades used to be a way to tell, but more and more vehicles today use reverse-rotation fans.

Can we just spin the engine using the starter? Assuming the starter works and engine rotates freely. Why makes life so complicated? If you cannot determine which way the engine rotates then it is better to leave the job to a mechanics who can.

The OP concerns is rotating it backwards may cause the Timing Chain to slip. It ain't going to happen with an OM603. I have done it many many times, CW, CCW, you name it.

I think the concern is resistance at the cam and IP might overcome the tensioner (with no oil pressure) allowing the crank to rotate ahead of the cam. It should be safe to turn the engine CCW through the cam sprocket but you might instead loosen the cam sprocket bolt.

Another telltale is the crank pulley timing marks. From a stationary point the crank should turn from BTDC to O* to ATDC.

Sixto
87 300D

Wow, thanks to everyone for the tips. I already have the head mostly off, was given a tip from another member that I really should set the cam and engine to TDC for cylinder #1. I don't want to turn the engine with the starter at all because I already have the guide rail pins out. My guess of looking at the fan turned out to be correct.

I spent lot of time working on my om617 engine, adjusting the valves once every 3 or 4 months, had it down pat. I have no real expirence with the om603, so I am just being a little cautious. Didn't know that turning the engine backwards was ok, I was warned by many trusted friends to never do that on a 617, just assumed the same applied here. I still don't think I'll turn mine backwards (out of habit would be the only reason).