Author Topic: Markings on crank that indicate TDC? (Read 3833 times)

anarchyx34 · « **on:** July 19, 2006, 09:33:02 pm »

I currently have my 1.6td on an engine stand so I can give it a freshening up before motor swap time. Anyway, I have the belt off, and the sprockets off (next step is the crank seal).. Anyway, I know how to get the cam and pump to tdc using the tools, but the crank I'm not 100% sure about and like a fool I didnt mark anything before I took the belt off. I know there's a mark on the flywheel that indicates such, but I dont have a flywheel since the motor's on a stand. It seems like the slot in the end of the crank for the sprocket's keyway seems like it just about lines up with the top bolt on the seal housing.

So does the above picture show a crank that is or close to (I may have moved the crank a little taking the pulleys off) TDC?

houseofdiesel · « **Reply #1 on:** July 20, 2006, 05:38:15 am »

Your looking at the wrong end of the motor, the tdc marks are on the flywheel. If you do not have the transmission on the motor your need to measure the distance between the two upper bellhousing bolts and the mark on the flywheel should be exactly have way if I remember right...others should comment too. You must have the flywheel on though, no other way that is easy. The front crank keyway would be way too inaccurate as one degree on that small a diameter would equal a couple of teeth on the timing belt...ouch.
Just install the belt once the motor is in the car, it is not that hard.

anarchyx34 · « **Reply #2 on:** July 20, 2006, 08:39:33 am »

Yeah, but how am I going to know if I put the flywheel on 180 degrees off or not?

houseofdiesel · « **Reply #3 on:** July 20, 2006, 01:00:56 pm »

You cannot install the flywheel off 180, unless you installed the dowel pins in the wrong place when resurfacing the flywheel. It only goes on one way

tylernt · « **Reply #4 on:** July 20, 2006, 05:04:34 pm »

Quote

You cannot install the flywheel off 180, unless you installed the dowel pins in the wrong place when resurfacing the flywheel. It only goes on one way

I dunno, you can install it 60 degrees off. I know, I installed mine that way. :oops: Oops.

Anyway, if the oil pan is off you can look at the pistons. At TDC the outboard 2 pistons are up and the inboard two are down.

anarchyx34 · « **Reply #5 on:** July 20, 2006, 07:40:58 pm »

I'll be taking the pan off tomorrow so I guess I'll see then. I have a feeling that the notch in the crank lines up with the bolt at TDC. We'll see.

Master ACiD · « **Reply #6 on:** July 21, 2006, 08:13:42 pm »

pull the 4 injectors out. put 1 finger in the first injector hole and turn the motor over with a breakerbar untill the #1 cylinder just stops blowing air out the injector hole. this is "close" to tdc.

it may not be perfect but atleast you wont be 180 degrees out.

anarchyx34 · « **Reply #7 on:** July 21, 2006, 09:31:50 pm »

Well I just had the pan off and I checked it out. The piston seems to reach TDC when the notch in the crank lines up with the bolt. However, I'm still not sure if TDC means when the piston reaches the top or when the connecting rod is pointing straight up and down, unfortunately I didnt pay attention to what was going on when I checked this. If the crank was off a tooth would there be piston-valve interference?

tylernt · « **Reply #8 on:** July 21, 2006, 09:54:57 pm »

Quote

I'm still not sure if TDC means when the piston reaches the top or when the connecting rod is pointing straight up and down,

The con rod will be straight twice, at TDC and again at BDC (Bottom Dead Center).

Here's a cross section at TDC:

And here's TDC again in a photo. The middle two crank throws are down (green), the outer two counterweights are down (red).

Author Topic: Markings on crank that indicate TDC? (Read 3833 times)

anarchyx34

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