Puma / Dorman 6LE / MacFarlane B46B / 110 kVA Generator Resurrection

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awemawson:
Time is pressing this morning as we have a luncheon appointment, but I'd intended to cut the hexagon on my bronze stock to re-make the heater unit as an integral (no joints) piece.

Sadly my bronze bar proved just too small so I've ordered a short length of 35 mm brass hex to make one later. However I thought that I'd have a go at re-making the first one I made - I'd thought I'd run out of silver solder and used silphos instead however a recent rummage has revealed another stash of various silver solders at differing melting points :thumbup:

So the plan of attack was to clean up the inside of the joint between the copper slug and the brass fitting and run a fillet of silver solder around it. First attempt didn't fully wet, but a re-clean in the grit blaster and re-flux cured that.

To inspect the joint properly I then again grit blasted it, and although it looks sound I decided to subject it to a 'bubble test' at 100 PSI. Cobbling various plumbing fittings together to adapt it to my airline I dunked it in a bowl of warm water and looked for escaping air. None apparent so I 'think' it is now sound.

PekkaNF:
Heaters are a little picky that way. When they are subject to changing temperature gradients parts tend to find weak spots.

awemawson:
No joy sourcing the correct heat exchanger sealing ring - parts book calls it an O ring (#576/35) but it has a rectangular cross section.

Simply Bearings delivered a pack of 4 mm x 83 mm and 4 mm x 84 mm normal O rings so I could try different fits. The original created a seal that very easily (too easily) could be pressed home. I tried the 4 x 84 first with copious amounts of Vaseline and careful pre-cleaning of the groove and taper on the adaptor. No way would it just press on, but pulling it on with it's mounting bolts it went home when I did a trial assembly. This let me pull it apart again and examine the O ring for damage, as possibly it could have had it's crown cut off. No visible damage so I decided to go with this size of O ring.

Out with the Blue Hylomar sealant, a light smearing on both sides of the gaskets then it was just a case of bolting it together - except for those bolts that are at 90 degrees to each other and clash. To get the engine side gasket aligned I had first to put it's bolts in, loosely tighten two of the ones around the O ring, remove the engine side bolts, put in the other two round the O ring, pull them up reasonably tight, put back the engine side bolts and rinse and repeat. All this fussing as of course as the O ring housing is drawn together, the alignment of the engine side bolts changes as the flange is drawn down the side of the engine ! Got there in the end.

Can't test it until I've sorted out the water jacket heater.

awemawson:
This afternoon I had a bit of time to start on the exhaust modifications.

First I plasma cut a flange with a 65 mm hole from 12 mm plate - first time I've cut as thick as that on the table. First attempt failed - lack of penetration (which wiped out a set of consumables) so for the second attempt I cut the tracking speed in half to be on the safe side, and all was well.

Then set it up in the 4 jaw chuck for boring and threading. "Take a 72.8 mm drill . . . " well obviously I bored it and threaded it to be a tight fit half way up a 2 1/2" male BSPT fitting.

All seems to screw together but I've still not finalised how the exhaust will run. It will be easier to get ideas when I have bits to screw together !

awemawson:
An exhausting morning - literally :clap:

Objective: to try and reduce the existing exhaust system to its component parts.

a/ Original exhaust flange is welded to a length of flexible pipe which is welded to a pipe stub, so that's not unscrewing

b/ Tail Pipe is welded to a socket fitting which is screwed onto the silencer - that unscrewed with heat and much effort

c/ Pipe stub on flexi screws into elbow on silencer - that again unscrewed with heat and a lot of puffing and blowing

d/ Elbow screws onto pipe stub on silencer - this has so far resisted all efforts to unscrew it. I've had it glowing red (oxy-acetylene torch) - I've shock cooled it with water, and tried several times but . . it want's to stay where it is :bang:

Never mind, I can still try a few layouts, and accept the limitation that it has an immovable elbow ! Without being able to unscrew the elbow, a drain plug in the silencer cannot be rotated to a functional position.

First vertical - probably simplest but I don't have the height where the generator is going

Secondly folding backwards then a 180 return to bring the tail pipe pointing forwards again. I prefer this lay out.

Either layout needs a short flexi from exhaust flange to pipe to avoid cracking the manifold, and #2 will need a heat shield to stop radiated heat downwards. Both will need some sort of support framework making with the silencer mounted on rubber suspension.

. . as usual all suggestions welcome :thumbup:

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