I need Help! Timing Belt Related

geordi · **Posted:** Fri Aug 10, 2012 12:36 am

There is no problem I know of with rotating the engine backwards by hand. I do not believe that a person could easily break a rocker by hand, turning it forward or backward, that would take a fairly large amount of force.

When trying to seat the crankshaft key on an old belt that is still installed - You can't. The cam keys will seat properly b/c they are very close together with each other, and hide the total stretch of the belt. The crankshaft is far away, and the keyhole will be as much as one tooth off, and will not be able to lock in. If the vehicle drove itself to the timing belt job, trust that when both top keys are properly installed, the crankshaft is in the correct position.

Just ensure that with the new belt tensioned, when the cam keys are installed, the holes in the crankshaft pulley are perfectly vertical and horizontal. Anything else is WRONG.

skates04 · **Posted:** Fri Aug 10, 2012 1:51 am

Your not going to break a rocker or bend valves turning it by hand unless you are really torquing on it with a breaker bar then maybe, If your helper felt resistance and stopped there should be no problem... I have never done a timing belt on a CRD but I have on many other vehicles and have never had a problem going backwards when getting everything in line.

Eric · **Posted:** Sun Aug 12, 2012 9:35 am

In general, no engine should be turned backward for any distance. When the oil pump turns backward it pulls the oil out of the galleys & returns it to the pan. This can result in a loss of prime & a dry start.

Of course there may be other specific reasons not to turn the engine (& transmission!) backward.

geordi · **Posted:** Sun Aug 12, 2012 12:12 pm

That might be true if the engine was capable of rotating backwards at speed - not by hand. The very design of the oil pump is that it moves massive amounts of oil through it to get to all the places the engine needs. The oil pump needs fast rotation for that to happen, and the drainback of gravity shows that the pump is not a sealed-flow design which holds the gallery full while the engine is off.

The oil viscosity (stickyness) is the only thing that keeps the engine surfaces covered while the engine is off, and prevents a so-called dry start. Rotating the engine by hand in either direction is not going to wipe that off or cause any heat buildup - it all happens too slowly.

Want to know the strength of an oil coating? After my wrecked engine had SAT on the ground, outside, with the cylinder top open, for 3 months... (Ask me how pissed I was with the mechanic about that) the internals were STILL soaked with oil and fully rust-free. Unfortunately the top of the block wasn't so lucky.

I need Help! Timing Belt Related

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