The Craftmans Shop > New from Old
Puma / Dorman 6LE / MacFarlane B46B / 110 kVA Generator Resurrection
awemawson:
Innovative use of Technology :clap:
We have had a LOT of rain in the last few days resulting in our 10 acre field flooding to an average of four inches (*) (local river tops it's banks and comes visiting), so it was no surprise to find a small puddle on the floor of the tractor shed under the generator but directly under the join in two roofing sheets.
But the timing seems strange - not directly as the heavens opened but some time later, so perhaps a small coolant leak, but the water in the puddle looked very clear - how to prove it one way or the other :scratch:
Well when filling the coolant up I had no idea if there was any anti-freeze in it or if so at what concentration, so I bought a cheap Brix diffraction meter calibrated in percentage Glycol. This will tell me if it's coolant or not!
With 15% Glycol it's certainly NOT a roof leak, we have a minor coolant leak. Sure enough I found a flange with four studs that allowed a good turn per stud - it MAY be the leak but anyway I'm satisfied now what I need to look for !
(I calculate that we received AT LEAST 4,500 TONS of water yesterday - probably much more as it runs off pretty fast - most was gone by lunchtime today)
awemawson:
I finally got the exhaust & Silencer assembly back on this morning, having given it a couple of coats of 'Stove Paint' - in matt black. Amazingly it took a full can and a half of aerosol (400 ml cans).
The exhaust manifold really should have a coat or two as well, but it's a horrid shape to mask up for spraying and I've not yet found a source of brushing stove paint.
Ran the generator up this morning to bake the paint - I was expecting quite a pong but it was surprisingly odourless :thumbup:
Update: I have now found a source of brushing high temperature matt black stove paint, but it won't be here now until second week of January, by which time I'll be in Barcelona !
awemawson:
I've been chasing a small but persistent coolant leak for a few days, and eventually traced it to the flange between the head and the thermostat housing casting. I wanted to fix it before moving the generator to it's new home as it is far easier to get at things where it is. The leak was dripping onto the charging alternator so definitely needed fixing.
There is a cross bar, bolted to the front engine lifting eye, that supports braces for the radiator, and this bar had been installed resting on the aluminium casting of the thermostat housing - probably for ease of setting out when it was built. This was no issue until I used the same cross bar to support the weight of the silencer. This weight was putting a shear force on the sealing flange and probably caused the leak in the first place.
The solution that I came up with was to raise the bar 6 mm and give it positive location not by resting on the casting, but by a pair of 1" angle iron verticals bolted to the generator chassis.
Verticals measured and test fitted then blown over with a coat of the same blue hammer finish paint, and put on one side whilst I investigated the thermostat housing / flange / gasket etc. Dismantling involved removing the associated rubber coolant hoses, an action that was far easier to write about than do! I'd hoped that I could re-use the originals, but they are rather manky. New silicone ones ordered (FOUR different diameters! 45, 47 50 and 51 mm!)
Unbolting the leaking flange I was surprised to see that it held two thermostats, each operating at 74 degrees C, and plumbed in parallel, presumably to double the flow :scratch:
Cleaning things up I drew up the gasket flange in Autocad, ported it over to the laser cutter as a DXF and cut some gaskets in two different gasket materials. The removed gasket looks to have been a cork one and hand cut, with bits over laying the thermostat bore in places. I'm not sure how thick it needs to be to set the right 'pinch' for the thermostats, hence cutting a few. I tested the thermostats in boiling water to prove that they opened - I didn't measure the temperature but frankly it's not that important so long as they open!
Hoses not arriving until middle of next week by which time I'll be in Barcelona, so play will resume when I return.
awemawson:
I had a pleasant surprise on Saturday evening when a knock at the door announced a Hermes delivery with my hoses that weren't due to arrive until Tuesday.
So today I set too. All fairly straight forwards but actually not simple as everything is extremely tight both to fit and to get at.
I started by fitting the cast elbow with it's two (different diameter !) hoses then moved on to the thermostat housing. As I had anticipated, the gasket thickness was critical, and initially assembling it with a single thin paper gasket I could slip a 5 thou feeler gauge between the faces when bolted up tight as the thermostats themselves were being pinched. I ended up using the two red fibre gaskets which are each just under 1 mm and it tightened up seemingly OK.
Filling it up with the six gallons of coolant that I'd drained off for this exercise all seemed well. I started it up and watched it running for five minutes while I cleared away my tools. Still all seemed well so I left it running while I cleaned myself up and downloaded these pictures allowing time for the generator to come up to temperature.
Going back to turn it off there was water EVERYWHERE :bugeye: The hose clip on the end of the heat exchanger had worked it's way off the end of the pipe :bang:
Now it had been murder tight but these silicone hoses are quite slippery and the pipes that they go onto have a cast in bulge to help sealing but in this case it leaves very little room between the end of the bulge and the end of the hose for a clip to sit, and if it's too close to the bulge you are tightening the clip on a tapering bit of pipe, which is what I think had happened.
Never mind, forgo lunch, drain down again, and re-make the joint :doh:
Second time round we seem to be OK - I left it again to come up to temperature, and, fingers crossed I think we are OK.
All a bit of a pain but at least it's done :thumbup:
awemawson:
One last job to do to complete the 'vermin barriers' on the generator - cover the holes in the bell housing.
I've been telling myself for a while that there is no need to do this, they just give access to where a clutch could be housed (although of course there is not one fitted) so just the engine to alternator coupling in there - no insulated wires to tempt them in to chew.
But the realisation that if a rat or more likely a squirrel, were to set up home in there, and I then started the generator, clearing out the ensuing mess would NOT be pleasant :bugeye:
So - simple job, draw up a cover taking it's mesh size from the existing ones that are on the alternator itself, and CNC plasma two (one each side), slap a coat of paint on, drill and tap holes in the bell housing to retain them then off for a cup of tea.
. . . well jobs don't always go to plan do they :bang:
The cast iron of the bell housing must be well chilled - it is as hard as a witches t*****y. Wanted to tap it M4, so 3.3 mm tapping drill. First drill bit went nowhere - never mind I have the remains of a box of ten HSS 3.3 drills. Next one blunted almost immediately. No cobalt drill in this size, so tried a 2.5 mm that I had to hand - it made a hole and then snapped on break through.
. . . so I've ordered up some 3.3 mm Cobalt drills, and when they arrive we'll see how gently I can drill some more holes. The tapping might get interesting as well !
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