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Correctly Timing the Crankshaft
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=85605		 Page 1 of 1
Author:  joe_ [ Fri Nov 18, 2016 7:28 pm ]
Post subject:  Correctly Timing the Crankshaft
I recently put the timing belt on after doing a bunch of work, and the thing's not starting. What worries me is, everything I read on this forum and in the service manual says that during timing belt installation, the flex plate locking pin should be in place and the front crankshaft sprocket for the belt should have its bolt holes at the 12/3/6/9 o'clock positions and the timing mark at the 3 o'clock position. However, I can't make both of these things happen.

When the bolt holes and timing mark are in the correct positions (and the red paint marker from whoever changed the timing belt previously is lined up), the timing pin doesn't go in to the flex plate.
Image Image

And when I rotate the crank so the timing pin goes in, all the markings at the front of the crank are one tooth clockwise from where they should be
Image Image

I tried lining it up both ways, but it won't start. Does anyone know which way is correct?
Author:  jws84_02 [ Fri Nov 18, 2016 7:40 pm ]
Post subject:  Re: Correctly Timing the Crankshaft
Ignore the markings on any of it. Crank needs to be at 12,3,6,9. With the mark at 3. With it there now you need to make sure each cam is in time. If you can't get the pins in the cams you'll need to remove the belt and each sprocket then lock the cams. Once all that is good, put the cam gears back on but leave them loose. Then put timing belt back on and tension it up. Then tighten the cam gears to 80lbs. Rotate twice by hand and check to see if pins go back in. Pray the rockers aren't damaged
Author:  joe_ [ Sat Nov 19, 2016 2:00 am ]
Post subject:  Re: Correctly Timing the Crankshaft
But the bolt holes for the harmonic balancer should be at 12/3/6/9 when it's correctly timed and the flywheel/flexplate locking pin is in place, right? What concerns/confuses me is that when the bolt holes are lined up (first set of pictures in original post), the flexplate pin doesn't go in. Rotate the crank clockwise a bit and the flexplate pin goes in, but the bolt holes are no longer lined up (second set of pictures).

As far as I understand, the flexplate is held on by 8 bolts, so there's no way for it to be just a few degrees off. And the crankshaft front sprocket appears to be keyed to the crankshaft from what I'm seeing in this picture from Mike92104's rebuild thread, so it's not like it can be removed and reinstalled in a different position like the cam sprockets. So how the heck are the front crank sprocket and the flexplate a timing belt tooth off from each other?
Author:  flash7210 [ Sat Nov 19, 2016 9:05 am ]
Post subject:  Re: Correctly Timing the Crankshaft
What kind of pin are you using for the flex plate?
I've always just used an Allen wrench.

Trust the crankshaft.
Don't know why the flex plate hole is giving you problems.
Author:  Rabert [ Sat Nov 19, 2016 12:07 pm ]
Post subject:  Re: Correctly Timing the Crankshaft
I had a similar problem when replacing the head gasket. If I aligned the flexplate with an allen wrench the crank would not be @ 3 O'Clock. I ended trusting the crank at the 3 O'Clock position. That was about a year ago......so far so good.
Author:  joe_ [ Sat Nov 19, 2016 1:59 pm ]
Post subject:  Re: Correctly Timing the Crankshaft
flash7210 wrote:
What kind of pin are you using for the flex plate?
I've always just used an Allen wrench.

6mm Allen wrench.

flash7210 wrote:
Trust the crankshaft.
Don't know why the flex plate hole is giving you problems.

Rabert wrote:
I had a similar problem when replacing the head gasket. If I aligned the flexplate with an allen wrench the crank would not be @ 3 O'Clock. I ended trusting the crank at the 3 O'Clock position. That was about a year ago......so far so good.

Ok, so maybe I had it right the first time.

I'm thinking I'll pull injector #1, stick an allen wrench down the hole, turn the engine, and see whether TDC corresponds with the crank bolts being at 12/3/6/9 o'clock.
Author:  joe_ [ Sat Nov 19, 2016 4:01 pm ]
Post subject:  Re: Correctly Timing the Crankshaft
Yep, cylinder 1 is at TDC when the bolt holes on the crankshaft timing sprocket are at 12/3/6/9 o'clock and the timing mark is right at 12 o'clock. So the crank sprocket is the correct timing and the flexplate is wrong.
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