Tuesday, 30 May 2017

Deep Breaths

For those who fancy python wrestling without the risk, might I suggest one of these?

You'll find them underneath certain SUL buses - those built after 1964, and some earlier ones which were retrospectively fitted. What is it? You'd better read on...

This is potential cause number (3) of 671's white smoke issue, albeit the least likely, but a job to be done regardless. It's the exceptionally elaborate network of pipes through which air is drawn, cleaned and delivered to the inlet manifold of the engine. 

Perhaps less well known than the equivalent statistic about arteries in the human body, it's nonetheless true that if 671's air intake was stretched out end to end, it would actually cover ground from Minehead to Lynmouth and back - twice.

Now, a quick lesson in SU air intakes, for those who themselves gasp with excitement at such things: 

Early SU buses, and all SU coaches, were originally fitted with air intakes on the front roof dome. The air was drawn through trunking above the driver's head (hidden by panelling on the coaches but exposed on the buses), the sound of which made for a noisy cab environment when the bus was pulling hard. There was also no air cleaner to remove unwanted particles from the air before delivery to the engine. 

Western/Southern National modified its SU coaches to draw their air directly through an oil bath filter, fitted under the floor alongside the manifold - as exhibited by 420, whose original intake vent wasn't re-fitted when the dome was replaced on conversion to dual-purpose. West Yorkshire (and very possibly others) also fitted air cleaners to their SU buses; as we know the floor is lower in the SU bus than it is in the coach, hence the intake and cleaner had to be taken forwards where there was more space. Later SUs were built to this spec and as a result, 671 has this big long python...

More to go wrong! The rubber sections of 671's had collapsed, restricting the air flow. The air cleaner was full of muck. The end cone was rotten and in danger of breaking apart. So I thought it worth wrestling the python onto the bench.

A thorough clean of the air cleaner (ironic) and pipes followed, together with new hoses, elbow joints and clips. 

But what about that cone?

A moment of midnight inspiration made me wonder if any similar cones were made for tractors - you know those little musroom things that stick up through the bonnet? The answer was yes - but also an identical one, for a Massey Ferguson tractor.

A double result at just £20. Something else now ready to go back on...

... just as soon as the chassis is dry. I did mention I'm working on that, too?

Breathe deeply...

Thursday, 25 May 2017

Just The Start

"Where do you even start?"

Human beings are wired to ask this question whenever they see somebody else's unenviable task before them. Usually it's rhetorical, an attempt at driving home what an idiot they think you are for taking on such an impenetrable project. 

But occasionally they genuinely do want to know the answer.

When it comes to restoring a bus there are different philosophies on the answer. Much as I look forward to making a visual difference to 671 (which in its current state prompts the rhetorical form of the question quite a lot), this idiot believes it's best to begin with the vital organs: all the various components and control systems associated with the chassis, the engine, gearbox, hydraulics, brakes, steering etc.

So that's where I've started on 671. 

Work since January has mostly been allied to the engine which was suffering with a severe white smoke issue. There are several potential causes, and consequently several work fronts to be started, all of which 'need doing anyway' whether or not they solve this particular problem.

First of all, the fuel injector pump. Having replaced the diaphragm in the pneumatic governor last year, it became clear that, really, the whole pump needed an overhaul. Of particular concern was that the cold-start mechanism was locked open, allowing excess fuel at all times and therefore one potential cause of the smoke (1).

Briefly, the cold-start is a device that helps the engine to start from cold by providing extra fuel. When the knob is turned, it allows the rack inside the pump (which governs the amount of fuel being delivered to the engine) to spring forward to a position where it's enabling maximum fuel to aid starting. When the engine fires, the vacuum created pulls the rack backwards, the spring inside the knob returns it to its original place, closing off the excess fuel position during normal running. 671's cold start mechanism was mangled and a tiny (but crucial) spring broken.

With expert help from Sheppard Senior and parts from my two donor pumps (useful having a pump that's common to the Fordson Major tractor, no?...), a strip-down and rebuild has resulted in a fully functioning cold start mechanism, and injector pump.

With pump absent, I've taken the opportunity to fully degrease, prime and paint the top of the block and some of the surrounding chassis. 

Incidentally, this operation was interrupted with an operation of a different kind on 671's owner, meaning that the first and second coats of silver were applied while trying not to burst nineteen stitches in the upper-abdomen - but that's another story!

Six goes with Jizer, followed by four coats of paint, have resulted in a much brighter and well protected environment. 

Learning from my endeavours with 420, my preventative pipe replacement programme has been extended to 671. I've made replacements for all the main fuel pipes, which were quite worn and mostly fitted with potentially troublesome press-fit olives. They all now have neatly braised 'proper job' ends, like these two seen under construction.

I've also had a new set of injector pipes made. Once bitten...

All this is now ready to be refitted, at which point we can address potential smoke cause number (2), the timing.

Meanwhile, in a world of many simultaneous workfronts, I've already been grappling with potential smoke cause number (3)... come back soon to find out about that.

Remember, this was just the start...

Monday, 22 May 2017

Since We Spoke...

Active restoration of BDV 252C has begun...

In fact, I've been 'at it' in earnest for nearly six months and there's now much to report. During a few rare moments with clean hands, I'll do my best to bring you up to date via a series of posts that show you the various work-fronts in action and explain what's been making me so filthy.

The project has continued apace since January, when 671 was moved from storage into an area where it can be immobilised and worked on in relative comfort for the first stages of its restoration.

Last year's preparatory work on the electrics and pneumatic governor meant that it would now start on the button and tick over without either stalling or gradually revving itself into oblivion - both little interim triumphs.

During the move, it was rid (at last) of everything that didn't belong to it, not least the dozens of unwanted bus seats which previous owners had heaped inside it. The interior, whilst depressingly worn after years of neglect, is all there and has dried out nicely after its first few months 'in prison' (for this is how it must feel to 671 after a lifetime out in the open).

Since January I've been gaining momentum with at least a day a week, often two or sometimes even three, dedicated to on-site restoration. Much else for the cause happens in between those days - the sourcing of parts and other spendings of money - but it's those days which move things along.

And moving along things are. Join us soon to find out how... and what this is....