rotate engine by hand?

[Gothmolly]

So I'm trying to replace a failed IP, and I need to bring the motor to TDC. Following the advice of some, I jacked the car, put it in 5th, and started rotating the passenger wheel. I got about 1/8 of a rotation and then bam, the thing stopped - it got to the point where the force I was exerting was twisting the whole motor in its mounts, but the thing refused to turn. I even pulled the GPs.

What's the trick for manually rotating to TDC ?

 

[mctdi]

Is the TB still on, turning the camshaft also?

 

[diy_fool]

Is the bad IP still in the car with the timing belt in place?

If it is, then the engine should turn.

If not, the camshaft won't turn with the crankshaft. So your pistons will hit the open valves as you turn the crank. The cam has to turn in time with the crankshaft to keep all clear. It turns at half the rate of the crankshaft.

 

[Gothmolly]

The belt is still on. Turning the wheel, everything turns, but then just stops. If I tap the starter, everything turns too. It just seems to jam up when I do it by hand.

 

[AndyBees]

TDC achievement

Is the IP locked or just not doing its thing? If it is not locked, getting the engine at TDC is a very easy task!

Put the tranny in neutral and use a "tool" to rotate the engine! IIRC, the crankshaft bolt is a 12 pt 19mm. Also, you should pop-off the TB cover so you can see that all is rotating. And, remove the "plug" at the bellhousing on the tranny side of the engine to see the TDC mark!

I've never heard of rotating a wheel to rotate the engine!

 

[diy_fool]

You're good, just need more torque.

Ues a tool like Andy says.

 

[DanG144]

Rotating a wheel, with the engine in 5th gear is a very quick and simple method of accomplishing the task. Passenger side wheel goes clockwise.

The 19 mm twelve point socket and breaker bar is what most of us use during TB replacements, but for cam inspections and other tasks I always use the wheel.

It sounds to me as if you may have excessive slack in the TB, allowing some internal component to impact when rotated by hand.

Of course it could be a CV joint, or issue in the transmission.

I would try the 19mm socket and breaker bar, clockwise only.

The starter can bend valves.

Do not apply more than about 50 lb ft of torque.

 

[ninedee_golf_tdi]

Put it back on the ground, turn the wheel hard right, use a 2' long, 1/2" inch extension with a 19mm 12pt socket on it and turn the crank clockwise as you're facing it from the wheel well..

 

[Gothmolly]

Thanks guys, the car ran fine before I parked it to swap the seal on the IP, so I'm puzzled why suddenly a) I have a bad TB, or b) there's something else jammed up. The wheel turn trick rotates everything with minimal effort until bango, it just stops.

Since the crank is inaccessible from the top, don't I need to lift the car to get to it ?

 

[RiceEater]

As diy points out you just need more torque. The transmission "multiplies" the engines torque; so it "divides" the torque you can apply by hand >10x (1st gear). Think about the principle of push starting.

 

[DanG144]

It sounds as if ninedee is saying you can do it on the ground with the wheel still on it.

I have always jacked it up, removed the tire, removed the side skirt, then used the 19 pt socket, when I want to use this method.

I will try his method one day.

 

[DanG144]

As diy points out you just need more torque. The transmission "multiplies" the engines torque; so it "divides" the torque you can apply by hand >10x (1st gear). Think about the principle of push starting.

It usually takes less than a 30 lb application of force to turn the wheel. Not hard at all, if you go slow (to let the pressure bleed off) or pull the glow plugs.

 

[Gothmolly]

As I said, the plugs are out, hence the confusion.

 

[DanG144]

Got,
I understand. I was simply saying that this is NOT a case for applying too much force. Normally very little force is required.

 

[Lug_Nut]

But he's in 5th gear, not first. The torque multiplication factor is much less (but the rotation speed is higher to maintain the torque*rpm constant). Plus he has the wheel diameter in his favor.
G-M, please tell me you didn't rotate the tire backward while in 5th. What that can do is have the crank pull the 'slack' and tensioner before the cam and pump and can cause the belt to skip or jump time.

 

[fruitcakesa]

I was about to post that engine rotation should be clockwise when viewed from the crank pulley side.
BTW Take off the TB cover and you can rotate it via the cam bolt with an 18mm wrench.

 

[diy_fool]

I missed the point about the glow plugs being out. So you have no compression to fight.

Fifth gear is easiest to turn over by hand so that part is right. I'm beginning to think Lugnut has a point. The cam timing may be off. Pull the timing belt cover and look for anything abnormal. You might not see anything though.

I'm backing off on my recommendation for more torque.

The belt is still on. Turning the wheel, everything turns, but then just stops. If I tap the starter, everything turns too. It just seems to jam up when I do it by hand.

If the belt jumped and the starter turned it over, there is a possibility of bent valves. The starter has a lot more torque than you and could power it through minor contact. So go slow here until you figure it out- no more starter.