Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Have stripped the engine to check the needle bearings and apart from two score marks on the outside of each one they seem fine, they look like pinch points when the crankcase is tightened up.Put the engine back together with new flywheel grub screws,the flywheels have a slight wobble after finally pulling them off and first firing there loose again, will have to try some hardened ones as Ade suggested.Still no idea why the engine stops any help would be welcome.Thanks Trevor.

Thanks for the offer Ade but I've already ordered some hardened grub screws will wait and see if that cures the problem.

The score marks on the bearings run across the outside , the drive side is worse than the other and quite deep running the whole depth of the bearing ,
does this suggest any particular problem ?.

Regards Trevor.

Hello Ade,
Here's some photos of the crank and bearings,the drive side appears to have flattened out when I reassembled everything and the other one now has a score going round as well as across itself.
Looks like new bearings may be needed, if you can email me on trram@tiscali.co.uk i'll send you my address,and take up your offer for some bearings.
It also looks as though the inside edges are wearing down any idea what could be causing this ?.
Regards Trevor

The engine is now running again with a new piston and ring , two new main bearings thanks to Ade(Yozhek) , and new hardened grub screws on the flywheels . New governor springs have been ordered as well ,  as the original ones had stretched to far , my fault . It's running on temporary springs
which will do for now.

Thanks for everyone's help in getting my engine running again .

Regards Trevor.

Hi Trevor,  you might continue to experience occasional flywheel loosening even with well to9oòrqued typical hardened set screws as the flywheel-crankshaft interface receives hard impulse hits. Hardened, serrated tipped self-locking type set screws grip the shaft better. Unless you drill & tap a new set screw hole about 90° to 100° separation, you're stuck with the Worst case, inferrior, 180° set screw locations. You might consider using Loctite Red on the set screws & glueing the flywheels to crank shaft with "on demand" debondable adhesive since after sorting out the crankshaft bearing issues flywheels seldom need removal. Have fun improving the beast, ...tom.