shovelhead failure - help : V-Twin Forum: Harley Davidson Forums

sdesla01 · 01-21-2003, 09:02 AM

700 miles after a dealer rebuild of my '69 shovel, I rode 7 blocks to the gas station and all was well. I turn off the the bike, filled up with 5 gallons o' premium and hit the starter to take off.

The starter engaged, the crank spins, but not the cylinders. I pushed the lump home and started to disassemble. I took the motor out of the frame and removed the heads. The pistons rock up and down as they should with no noises when I push down on them, but I can turn the crank by hand without moving the cylinders. Just clicks and clicks. No pushrod movement or anything.

I need some help on the possibilities of what failed before I split the cases. Any direction would be greatly appreciated.

Steve

shovelbolle · 01-22-2003, 12:15 AM

>>The pistons rock up and down as they should with no noises when I push down on them, but I can turn the crank by hand without moving the cylinders.<<
...moving the cylinders ???
Maybe state this again.
No pushrods moving ? No lifters moving ?
How`s about the pinion-gear ?

However this is a case of dealers warranty. ****er refuses ?
Burn the shop down. Shoot the mechanic.

ray

Roger48 · 01-22-2003, 12:52 AM

This post must be a gag, we all know that the dealer won't work on a Shovel.

wyodude · 01-22-2003, 04:49 AM

Quote:

Originally posted by sdesla01
The pistons rock up and down as they should with no noises when I push down on them, but I can turn the crank by hand without moving the cylinders. Just clicks and clicks. No pushrod movement or anything.

Steve,

If you can turn the crankshaft by hand and the pistons don't move, then both connecting rods have snapped. If this is true, it is very difficult to beleive it just happened (I'm not doubting you, just stating an opinion). Connecting rods usually fail at very high rpms.

wyo

sdesla01 · 01-22-2003, 08:19 AM

The pistons rock up and down as they should with no noise - the rods are intact on the crank - nice and smooth still. No metal shavings in the oil when I drained it. It is as if the flywheel is disconnected from the crank. Just have never seen anything like that before.

steve

chopper_larry · 01-23-2003, 05:09 PM

I hope you mean "you turn the crank by hand, and the PISTONS don't move" (indicating very severe lower end problem) ...... the cylinders NEVER move. Need more info. It's possible but unlike IMO, that ALL
the lifters went down at the same time. Do you let the motor warm up before hard revving? And what was your style of break-in?

chopper_larry · 01-23-2003, 05:17 PM

I hope you mean "you turn the crank by hand, and the PISTONS don't move" (indicating very severe lower end problem) ...... the cylinders NEVER move. Need more info. It's possible but unlikely IMO, that ALL
the lifters went down at the same time. Do you let the motor warm up before hard revving? And what was your style of break-in?

jcrow · 02-22-2003, 08:49 AM

This doesn't make sense, sounds like the flywheels are spinning on the crankpin. Where are you turning the crank from?

58Panhead · 02-23-2003, 09:21 PM

If you seriously need some help, rewrite your post, or have someone rewrite it for you. I need a little more clarification on "the thingies don't spin when I pull the handle"

AndrewM01 · 02-25-2003, 03:05 PM

I never worked on a shovel, but lots of other engines in the last 40 years or so. Its hard to understand from your description, but I gather the OUTPUT SHAFT, the one the primary drive sprocket lives on, the one that stricks out the main bearing in the left case, will turn but the rest of the crank assembly doesn't. That shaft has a tapered end that fits into a matching taper in the flywheel on that side. There's usually a key in a groove that helps transmit the drive force. The shaft is held in the taper by a nut on the inside of the flywheel. This nut is turned down to a very high torque. Now, if someone forgot the key, or it broke, the high torque on the nut would provide enough friction in that taper so it'll drive for a while, but that'll loosen up a bit with heat and stress (we're talking maybe .0001" or .0002" here,) and the crankpin will just spin in the taper. As soon as it turns, even a little, the tapers, which have to be a perfect match, will get buggered up, and it won't drive again. Maybe a really good machine shop with precision grinding equipment can save the pin and flywheel, but its good odds you'll need new ones. I have seen this one before but its really rare. Hope its something else...
Andrew

PS Its possible that the shaft itself broke, but I'd think if it did the flywheels wouldn't run true in the case and there'd be a terrible noise. Its just barely possible the cam side shaft would hold it true enough to turn, though. Same diff, new lower end parts and setup, though.

D.Ed · 02-25-2003, 08:50 PM

Sounds to me that someone forgot to torque the sprocket shaft. It ran on the key until it sheared and is now jusy spinning in the flywheel. Seen alot of this in the early '80s when HD went to the big taper on the sprocket shaft and they were using to low a torque rating. Everyone I saw spun while cranking on the starter. Take it back to the dealer and *****. Otherwise you will have to pay for it all over again.