My 914 1.8 crankshaft Question

[kim914]

I recently took off my 1.8 head and clean up a little bit and replace all gasket and seal. But now I reassembly all parts together and trun the impeller. Find out the crankshaft can be move back and forth. Is that how the way is?

Thanks guy

Kim

[Jason Porter]

The crank moves back and forth inside the case, while the case is assembled???

That's not exactly what you want, unless I'm way off base here. That could cause vibration, bearing failure, a piston hitting a head, or all of the above.

Did you loosen/remove any case nuts/bolts? How much play is there? Has the engine been rebuilt? Is the crank moving front to back on the engine, or side to side?

[Dave at Pelican Parts]

Most importantly: Is the flywheel bolted on? If not, then don't worry about it yet. If the crank has fore-and-aft slop with the flywheel bolted on (and with the three shims behind the flywheel seal), then you need to figure out how much slop ("crank end-float") there is.

There is a spec for it, listed in the various manuals (e.g., Haynes). It's a very small number, just a few thousandths of an inch. If you have significantly more than that, and the flywheel and shims are in place, your engine is dead. It may run, but it will be running on borrowed time. Time to either look for another engine, or rebuild this one and have it align-bored.

Note that align-bore bearings for the Type IV motor can be tough to find. They don't need it every time they're torn down, like the Bug engines do, so there isn't a large supply of the bearings for it. It might be easier just to find another motor with a good case, or even a runner.

--DD

[kim914]

I did not take one of the crankcase bolt off. I just clean up my head and put everything back together, and the crankshaft is move back and forth (from flywheel end to impeller) while I turn back and forth of the impeller.
I have not install the flywheel yet and have the play is around 1/8 inche.

Thanks for replay with all information

Kim

[Dave at Pelican Parts]

If the flywheel isn't on the crank, then you should be OK. You'll probably want to meansure end-float once you get a flywheel in place (and torqued), in order to make sure you've got the correct shims.

--DD

[DDS]

Yup, the flywheel pins the shims.
You set the end play using the three shims before you install the crank seal. You will have the flywheel on and off to do so. Make sure you measure between its extremes, tapping it with a mallet can help.
Didn't know that with three shims in place and excessive end play that the case was dead, I thought you could just re-shim and be ok. Makes sense if the wear is on the non-shim end of the travel I suppose. Could it not be the flywheel side that wears or the shims themselves or the main bearing with the thrust surface?
Why would align boring correct an end-play problem?

DAve

[Zeke]

Originally posted by DDS
Yup, the flywheel pins the shims.
You set the end play using the three shims before you install the crank seal. You will have the flywheel on and off to do so. Make sure you measure between its extremes, tapping it with a mallet can help.
Didn't know that with three shims in place and excessive end play that the case was dead, I thought you could just re-shim and be ok. Makes sense if the wear is on the non-shim end of the travel I suppose. Could it not be the flywheel side that wears or the shims themselves or the main bearing with the thrust surface?
Why would align boring correct an end-play problem?

DAve

All very good questions. And RIMCO usually has a supply of oversize bearings for align bore. They run about $75.

[Dave at Pelican Parts]

As I know from experience:
The wear appears to primarily happen on the thrust surface of the main bearing. This can be replaced, no problem.

However, the slamming back and forth and slopping around will often cause problems with the bores. They need to be at the very least checked--chances are pretty good that they will need to be re-bored.

I'm glad to hear that the align-bore bearings are getting easier to find now. They have varied between "tough to find" and "very tough to find" for quite a few years now.

--DD

[DDS]

Ahhhhh. Hopefully Kim's was sloppy 'cuz the flywheel was off.

Dave