1955 Model D150 Version 2 - Painting engine

[Big Al]

I need to repaint my engine to its original finish. At the same time, I will be replacing all the gaskets at the various joints, and replacing any worn bearings, etc.
After removing the small transmission end cover, which contains the oil filler plug, will I be able to easily replace the cover against the spring action of the dished washers which act on the plate which retains the bearing?
Also, at the opposite (front) end, can the transmission case be disconnected from the gearbox without displacing any of the transmission or gearbox components?
I am happy about removing the flywheel, and the clutch cover, although I expect to have to re-adjust the clutch cover nuts on the pull rod once everything is back together again.

[Steve J]

Removing and replacing the rear cover on the tailcase is not a problem - just remember to replace the two dished washers with their inner edges touching each other. Get it wrong, the washers apply no pressure to the alloy bridge piece, and the pinion group will slide back and forth, causing wear to the crownwheel & pinion teeth. The spring action isn't that strong - just tighten the 4 retaining bolts evenly to make sure they all take the load as you tighten them. If you split the tailcase from the main casting, the laygears and the sliding upper gear will come out, no doubt about that. If the engine is out of the frame, it's not that difficult to reassemble the gearbox & the two castings. Try and do it with the main casting in the frame & it's about 10 times more difficult!

[Big Al]

Many thanks, Steve. The engine is already on the bench.
If I turn the engine upright, so that the rear cover is uppermost and the clutch cover is at the bottom, will that prevent the laygears and sliding upper gear from coming out when I split the tailcase from the main casting, or is it not worth worrying about? I know some of these things turn out to be easier than they appear from reading the manuals.
Alan

[Steve J]

If it's on the bench, don't worry about it! I'd be inclined to split the casings anyway, and have a close look at the state of the gears and the selector parts - especially the state of the engaging 'dogs' on the gears, the splines on the mainshaft & layshaft, and the spring loaded roller for the gear selector. Discovering that the gearbox jumps out of gear when it's all back together is a real downer, believe me!
Reassembling the gearbox is not that hard - the way I do it is to clamp the tailcase vertically in a vice, with the gasket face uppermost, and lower the main casing onto it, engaging the mainshaft as I go. The trick is to assemble all the gears into the tailcase, engage 3rd gear to locate the upper sliding gear against the final driven gear (the one splined to the torsion driveshaft), and rotate the mainshaft so that its splines will slide directly into the upper sliding gear. Get it all carefully aligned, and it goes in first time (with a bit of luck).

[Big Al]

Thanks very much, Steve.
I will take your advice, and check out the state of all the parts.

[Big Al]

What is the best way to prepare the engine for painting?
Should I just degrease and lightly rub down with a fine wet and dry paper?
How should I treat the cylinder head and barrel before painting? I have a pressure washer for cleaning patios etc. Could I use this instead of vapour blasting for example?

[Steve J]

I'm no expert on this, but wire brushing the alloy casings works quite well for me, and degreasing the surfaces before painting is essential. Rub the casting down with wet or dry paper by all means, but if you are going to try to replicate the original finish, you may end up with a surface finish on the alloy which is actually smoother than the original. As far as I'm aware, the cylinder head was never a painted item, and I'd be inclined to clean it to bare metal and call it a day! Get all the rust off the outside of the cylinder if possible - bead blasting may be the best alternative, but wire brushing may clean it up sufficiently for the high temperature paint to stick. (I'm sure the paint used for painting barbecues doesn't require - or often get - a totally rust-free surface. Some on here have used it to paint expansion chambers, so a D150 cylinder shouldn't be a problem...) Domestic pressure washers are OK for removing loose dirt & crud, but my limited experience is that they are not very effective at removing all the old paint or baked-on deposits.

[Big Al]

Many thanks, Steve. Very helpful.