Engine Painting

I've always tried to do b) for anything that I've got completely in bits, but it never quite works out perfectly because I always seem to manage to chip, scratch or scuff something that I shouldn't which then requires some touch-up (and as you say, things like bolts etc. need to be done afterwards anyway).

I'm crap at painting, too - I always get more on me or the surrounding area than I do on the thing I'm supposed to be painting :-)

I allways paint the indavidual parts as i think it gives a really clean look where ever you have a gasket , I replace the nuts with whitworth stainless and then use small washers under then to stop the paint from chipping when undone, the problem with painting the nuts comes when you have to take something back off.

rgds bob

I tend to basically follow (b) although my preference is to replace all bolts, nuts & washers with new stainless steel items and to paint with "engine paint" which needs no primer or undercoat, thus avoiding too much buildup of paint in corners, etc. Pete

On the rare occasions that an engine is so far gone as to need re-painting (cue John - yawn :-), also B though definitely NOT using SS fasteners or washers that did not feature on the original.

ttfn

Not only do they not feature they are, apart from the thread, the wrong size and expensive.

The SS fasteners I've seen are all made to the same dimensions as carbon steel ones. However, they do not have the same tensile properties, unless you've got some really grotty originals that is. However, on older engines, this is rarely a problem. As for painting engines, there's no fixed answer. I tend to paint them after the major components are assembled provided they are the same colour and finish. That way gasket and mating surfaces don't get contaminated by paint. The type of paint used for a 1900 engine will be very different to that needed on a 1980 engine. I know this isn't an engine, but for an example of what can be achieved, have a look at this rebuild

bow to an expert here. He has rebuilt a machine to the highest standard. The end result is not only beautiful but useful as well. I've always looked upon machines as a means to an end rather than an end in themselves.

John

My understanding is that stainless steel fasteners are usually stronger than ordinary steel, but a little weaker than the lowest grade of high tensile steel. Personally I would not replace the original fasteners with stainless steel, except possibly on exhausts, as they corrode badly.

Does anyone know the complete and accurate story behind the reduction in the across flats dimensions of Whitworth fasteners? I have heard that the dimensions of the heads of fine-threaded fasteners were reduced by one size during WWII as an economy measure, but have encountered some coarse-threaded fasteners which also appear to have smaller heads.

Best wishes,

Chris

My general inclination is not to repaint unless really necessary. Working clothes are best. That said, I do like brushed aluminium and if the finish is quite irrecoverable (I like younger engines) will remove ancient corrosion & the remnants of paint with a brass cup brush and leave the bare aluminium unpainted. In some cases I might lacquer it. Tinware, cylinders & heads in cast iron must of course be satin black. I ALWAYS leave an out of the way area of original paint in case a later owner wants to reverse my choices.

I don't replace reusable plain steel nuts nor do I paint or coat them. I find that the slight oil film that pursues even the best kept engines will keep them rust free if the engine is frequently run.

Regards,

Kim Siddorn

"THE DOUGLAS STATIONARY ENGINE RESOURCE (admin)" wrote in message news: snipped-for-privacy@brightview.co.uk...

I never feel confident using ss fasteners in stressed or structural areas, OK for trim and baffles etc, but that's about it. Stainless on stainless will not torque up reliably, the material binds up on itself and a fastener that you think is tight will undo virtually with finger pressure.

I think the characteristic is caused by the chromium in the alloy, and is the reason why you can't use chrome plated piston rings inside chrome plated bores.

Julian.

I've rebuilt various bikes over the years and fitted many stainless fasteners of all threads and configurations. I recall that SS nuts, bolts & washers were standard fittings on the gas turbines I worked on thirty odd years ago - indeed, I still have a small selection from those happy days.

Now I think about it, they DID come supplied with Nyloc nuts or those locknuts with a double slot machined into the locking part.

Never thought much about it until now, held brake drums on wheels, rebuilt Vincent front forks .....

Yikes!

Regards,

Kim Siddorn

Galling is a problem on Stainless and Titanium fasteners, which can be relieved a but by anti-seize compounds etc.

We've used them on the trailer successfully, st on st, with no big issues, but oiling them first helped prevent any unexpected locking up.

Peter

-- Peter A Forbes Prepair Ltd, Rushden, UK snipped-for-privacy@prepair.co.uk

Well done John I thought you were going to go off on one with the subject of painting :-))

Every machine my company builds is with Stainless Steel, 316, and they wouldn't know lubricant if they fell in a vat of it, This week I needed to get a panel off without damaging the face of it so ended up very carefully drilling a seized M5 Allen bolt with a 4.2 mm drill so that I could remove it and recover the thread. Its not unusual to use a slightly larger drill for tapping to stop the seizing occurring.

Martin P

It's certainly a problem, the first hit on google gives this, which is fairly interesting reading:

Since Screwix started knocking out SS fasteners at such cheap prices I stocked up on their entire range for my workshop and used them whenever I could - after a few surprises due to galling I now have a lot more respect for this problem and only use them in non critical situations. I think you're OK if you use stainless on HTS, but stainless on stainless is where the problems potentially arise.

I don't know much about the GT's you worked on, but I don't remember any ss fasteners on modern(ish) engines like the CF6. IIRC mostly quality HT steel and cadmium plated for corrosion resistance. Also an abundance of slimmed down nuts for use in shear applications. Could be wrong as my memory isn't

100%

Julian.

Hello

Thank you to all those who responded to my original post (below). I appreciate your comments.

The consensus seems to be: Prime, undercoat and top coat individual parts and then reassemble, painting nuts as appropriate.

However, if none original washers and nuts are to be avoided, as Roland suggests - are there any hints and tips for avoiding damage to the top coat at assembly when tightening nuts etc?

Regards

Ade

My advise is just to purchase a nice little artist's paint brush and touch them back up afterwards, that's what I do when I'm reassembling my junk!

Julian.

If the nuts are sound then I lightly chamfer the inside corners. Not strictly correct but avoids the paint damage. I do the same when making new ones.

hth Roland

Shouldn't that read 'outside corners'? Washers work here as long as they don't rotate. Assembling while the paint is new (dry but not hard and brittle) also helps especially if washers are used. Be carefull when painting any mating areas or where fasteners seat. The paint will stop metal to metal contact. The inevitable vibration will result in movement that rapidly destroys the paint and the fastener ends up loose. It's also possible to build up a cumulative error with paint. I built an engine and painted evrything, including mating surfaces. Every joint was therefore held slightly apart despite tightening the bolts. The engine ended up measurably larger to the point where it wouldn't fit into the subframe.

John

I don't quite see that as it only increases clearance at the root of the thread. The flanks and bolt tip remain unchanged.

John