Agriland Article 21.02.2018
One of our visitors at the recent Q8 Millstreet Spring Farm Machinery Show was Justin Roberts. He very kindly offered to visit our premises in Douglas Street and contribute an article to the Agriland online magazine. Have a read of the article below.
Trade focus: ‘Lifting the lid’ on what an engine specialist does
The internal combustion engine has been with us for over 150 years; it has come a long way since Beau De Rochas patented his four-stroke design in 1862.
The increase in power we have witnessed has (in some cases) been matched by an increase in reliability. Yet, they can still go wrong; they can still ‘give trouble’.
Thankfully, when it all gets too much and the motor fails there are firms willing to dismantle it… and re-engineer the various parts to help prolong the life of the unit.
One such company is Murphy Engines Overhaul of Cork city; it has been serving the motor trade since 1967.
Initially, there were four brothers who started off repairing and supplying electrical components – such as starter motors and alternators.
During the early 1970s this business divided into two, as engine refurbishment began to play a larger role. So, the present company branched off – to specialise in that side of the trade.
Today, it is still a family-owned company run by Micheal Murphy (who joined the business in 1984). Micheal is a keen advocate of engine re-manufacturing and is enthusiastic when explaining what it entails.
He also knows about the pitfalls of not doing the job properly, or maintaining an engine as it should be.
The head is the most vulnerable part of an engine; it is the most stressed part and the first to give problems.
It is the repair of this major component that makes up a large percentage of the work.
Valves, especially, are subject to damage as they suffer high temperatures and continual pounding against their seats. Micheal noted that replacement of the seat, with the correct insert, is the only way to counter the recession of the valve into the head.
“You cannot match the manufacturer’s tolerances by simply re-cutting the seat,” he insisted.
Skimming of heads and blocks
Another regular job undertaken is the skimming of both heads and blocks. Most of this is done on a manually-operated surface grinder.
Grinding can cope with aluminium and iron, or a mixture of both, where steel cylinder liners are present in an alloy block. Manually-operated machines offer greater flexibility – an important advantage given the huge variety of components being worked on.
“I could only justify CNC tools if we worked with regular production runs of the same engine, rather than individual jobs,” noted Micheal, as he pointed to the sheer variety of engines awaiting attention in the workshop.
Often the company is asked to undertake complete rebuilds, involving all these steps. However, care has to be taken in balancing what is possible and what the customer may expect.
For instance, as an engineering machine shop Murphys is not in the business of building ‘race’ engines, and avoids doing so – except for the machining operations the company is equipped to handle.
This philosophy extends to commercial and agricultural diesels, where an engine’s ancillaries and final set-up are left to the customer. “We can stand by our work but we cannot be responsible for the way it is installed and operated,” explained Micheal.
“A lot of our work comes from experienced mechanics who know the extent of what we do and – by the same token – will know exactly how to re-set the engine when it goes back into the vehicle.”
Engine failure may not always be the fault of the operator, Micheal said. There were some families of engines that had basic design flaws, although he wasn’t too keen to say which.
However, at the mention of the porous Ford block he believes that, despite the improvements that Ford made in addressing the problem, it never quite remedied it totally.
“There is always a gap between an engineer’s design and the practical application,” he explained. “Sometimes that gap is tiny; sometimes it is huge.” It’s as diplomatic a way of putting it as any.
The ‘chipping‘ of tractors can also cause problems, despite the tales of bravado that often surround this activity.
Although two tractors rated at different power levels may appear to share the same type of engine, there are often differences Micheal suggested.
Cooling capacity is one obvious distinction, but there may be more subtle variations – such as the (material) composition of wearing items – valves and bearings in particular.
If someone wants 180hp, then they should buy a 180hp tractor.
He is also less than enthusiastic about the reliability of some common-rail injection units.
“They offer tremendous advantages in terms of power and efficiency, but they are not as robust as the old injection pumps,” he noted.
“Fuel quality is much more critical with modern injection systems,” he claimed.
Lubrication is another area that’s vitally important to engine longevity. Here, he highlighted two golden rules.
Two golden rules
The first is to always use the specified oil and the second is to change it within the recommended service interval – not afterwards.
As for the extended service intervals now being recommended he thinks that many manufacturers are being “over-optimistic” and urges that oil be changed before reaching the limits suggested in some handbooks.
Besides the engineering side of the business, Murphy Engines Overhaul is an agent for Yanmar diesels, alongside various ‘original equipment manufacturers’ (OEMs).
Wherever possible, the company uses components sourced from the latter, but around 20% of parts will – unavoidably – come from third-party suppliers. This is especially the case with older or less common engines.
However, they will consider overhauling any make or age of engine, if they think it’s possible and the parts are available.