Crankshaft question - Predator 301

[Fordiesel69]

I have a technical question about output side of a crankshaft. I removed a briggs 305cc 10HP engine that failed, and its 1" shaft with 1/4 in keyway was extremely tight against the fan impeller I removed. It required a bolt to be threaded in the nose of the impeller to get it off the shaft, and my impact had a hard time.

The harbor freight engine has a large diameter plain bearing surface where it exits the engine case, then the machine it down to 1". Overall the predator is longer overall, but actually a touch shorter on the part they turned down to 1". This causes the impeller to bottom out on the back side as shown by my larger circle in the photo. On the old engine it would bottom out on the front surface of the crankshaft where the bolt is shown by my smaller circle. Will this be of any concern?

To avoid any galling or the impeller loosening up, I coated the crankshaft heavily with shaffers extreme pressure moly grease. Then installed the impeller, and locked a grade 8 bolt with a lock warsher plus blue loctite.

Can anyone see any issues with this? I explored the idea of removing the impeller again and cleaning off the grease and use that special loctite that locks things down on splines. (like the stuff you use on differential input yolks.)

 

[DriveHard]

Do you have a similar drawing of the impeller? That design will answer your question more quickly than the shaft design. You need to know how it can take the load you are putting on it.

 

[ironman_gq]

Is the impeller keyed? I've always put those things together dry, lube just lets things move around more and that's typically a part you don't want to be moving.

 

[Cujet]

Without knowing how robust the impeller is, it would be impossible to know whether using the inboard side as load-bearing, will suffice.

As I understand this, previously the bolt side of the impeller would be clamped against the crankshaft.

However my guess is that it will be fine. In general when a bolt is under tension due to significant stretch, it is more reliable. A situation like this could be similar, depending on the components, as the bolt is not bottomed out but instead has load on it from compressed and stretched components.

The other option could be inserting a shim-washer inside the bore of the impeller.

 

[wings&wheels]

Assuming I understand this correctly, the only thing I would be concerned about is that if the impeller is butting against the shoulder, not the end of the crankshaft, the impeller area under the bolt head is not supported by the crank nose and I would be careful when tightening. If you have it all together already and it works, then I would not worry about it but keep an eye on it for a bit.

 

[Fordiesel69]

Impeller is keyed. No drawing of that unfortunatley. It is together and working and the only reason for the moly grease is that a youtube channel did this same engine transplant on a different model, with one of those junk blue dura maxx engines and the crankshaft galled and basically lathed itself to destruction. Loose I bet my friend will feel vibrations. Galling may just up and snap.

So far so good. 1hr of runtime and bolt did not loosen and no new vibrations. Acutally no vibrations outside of a typical lawnmower..

 

[The_Eric]

Grab pair of calipers and measure the difference between the depth of the impeller and length of the crank and add the corresponding amount of washers between the end of the crank and impeller.