Main and Auxiliary Engine Repairs at Sea
I joined my first ship the MV Orama; a 39,000T oil tanker, in Portland Maine in 1966 as Junior Engineer (actually15th Engineer ). I had just finished serving my time as a marine fitter at Harland and Wolff Belfast, leaving there to join the British Merchant Navy.
Over the few years I gained promotion, and in 1968 was sailing as Third Engineer on MV Torr Head; an Ulster Steamship passenger/cargo vessel that carried six Engineer Officers and an Electrical Officer.
The following sections describe the breakdown of a diesel driven generator, leading to the second most dreaded condition at sea; (fire being the first one) a blackout!
The first section takes us on a short tour of the engine room of the MV Torr Head – remember please that this was over 40 years ago, so some of the details are a wee bit hazy.
Quick Tour of MV Torr Head’s Engine Room
As I said earlier, I was sailing as Senior Third Engineer awaiting the results of Part A 2nd Engineers BOT Certificate.
As you step into the engine room of any ship you are greeted with the heat, noise, and the familiar mixture of different smells: hot oil, diesel, and faint exhaust fumes.
Entering this particular engine room was no different; walking along the top plates gives access to the cylinder heads, with the air start and relief valves, fuel injectors, and exhaust gas pyrometers. Working our way down, the next levels contain the turbo-blowers, fuel pumps, the oil purifier room, the workshop and spares store, switchboard, and so on until we reach the bottom plates. Here the crankcase doors, main engine controls and instruments display panel are located. The bottom plates also contain the three diesel generators, numerous oil, fresh water circulating pumps as well as the seawater water supply and cooling pumps, coolers, and the exhaust gas boiler.
Aft from the control station is the thrust block and propeller drive shaft that enters the shaft tunnel through a water tight bulkhead, our access being through a manually operated watertight door. Here the shaft continues supported on white-metaled bearings before exiting the after hull through the stern gland and stern tube to drive the propeller.
Blackout!
I was sound asleep and rudely awakened by a banshee-like howl, followed by the main engine slowing down.
I jumped into a boiler suit as the lights went out and headed down to the engine room, making directly for the standby generator. I fired this up and the electrician, who was already at the switchboard sporting red underpants and engine room boots, promptly put this genny on line. Immediately we had power again, and by this time the rest of the engineers were arriving and re-starting the various pumps.
Once all the pumps were running again the Second restarted the main engine and the Chief informed the bridge that we were back in business.
I was due on watch shortly, so once things settled down the rest of the engineers went back to bed and I stayed down with the Fourth Engineer, and asked him what had happened.
Seemingly the howl I heard was from the generator turbo-blower, and he hit the Engineers Emergency Call Button, put the engine room telegraph to stop, and stopped the main engine.
He then ran over to the generator and hit the emergency stop - lights out!
This was not the way I would have done it, but he was a first trip Fourth Engineer; and he did well as it turned out.
In the next section we find the cause of the generator breakdown, and how we repaired it. In those days we had to repair the equipment as best we could; if there were no spares- we made them.
What Caused the Generator to Fail?
The Chief rang down and told the Fourth to stay on watch to allow me have a look at the generator to see what the problem was; the Old Man had been on to Head Office and the shore-side engineering superintendents wanted answers. Luckily it happened when we were in the middle of the North Atlantic, so the ship had been in no immediate danger.
Back at the generator; I removed the rocker-box covers and immediately was aware that the rocker gear was bone dry- not a drop of oil in sight. My Junior Engineer was turning the engine over with the barring gear and I noticed one of the exhaust valves was stuck open, with the rocker at the closed position. It had obviously seized open due to lack of oil; so this was why the turbo-blower had been howling at the moon.
The Chief had appeared again, smelling nicely of rum, and I told him that I had found the problem, but not the cause. However the cause was soon traced to the rocker gear lube-oil manual control valve; it was shut, starving the components of oil.
The Chief went off to inform Head Office, and I took over my watch again.
As Third Engineer I was in charge of the generators, so I regarded them as my babies and had stripped all three generators for routine maintenance since being on the ship, but had never had any trouble with them before this.
Back at the generator, I opened the oil control valve again and told our greaser to pump up the oil pressure using the hand pump, whilst my Junior Engineer kept baring the engine over and I made sure none of the other valves or rockers had seized, fortunately these looked o.k.
Stripping the Cylinder Head
The Second came down early and took over the watch allowing me and my Junior to get back to the generator. We disconnected the fuel oil, lube-oil and air start piping from the defective cylinder head before removing it and getting it up to the workshop for a closer examination.
A four-stroke diesel engine cylinder head contains the inlet and exhaust valves, rocker gear, cylinder relief valve air start valve and fuel injector. We soon discovered the rocker arm for the exhaust valve was indeed seized on its shaft and, the exhaust valve stem seized into the phosphor bronze valve guide.
What a mess; where do I start? Times like this I wish I worked ashore and could call in the manufacturer team - not really, looking back this is why I served a marine fitter apprenticeship; now was the time to put it into practice.
I removed the rocker arms and shaft, sliding the inlet valve rocker off the shaft after applying a little oil; it was very slack fit on the shaft.
The bushing was badly marked, but we might get away with it, albeit with excessive clearance. The seized exhaust rocker arm took a little more time; I rattled it off with a copper hammer, being careful not to damage the shaft. This rocker arm brass bush was very badly damaged and there was no way we could use it again.
I oiled and then knocked out the seized valve stem and gave it a wee rub with emery cloth-good as new- thankfully; the valve guide looked fine on closer examination.
I laid the pushrods on the stainless steel workbench top and did a quick check; thankfully they were straight and undamaged.
We carried the obvious spares for the generators, a couple of exhaust and inlet valves and springs, cylinder liners, pistons and rings, etc; but no rocker arm bushes, valve guides or push-rods. It was my job to order generator spares as required, but as I had never used these components at maintenance overhauls, I never ordered any. However I made a note to order these and have them delivered to the ship next time in Belfast.
We also carried a couple of lengths of steel and brass round bar, for machining bits and pieces for equipment. I kept these locked in my generator spares store (a tip I learned on tankers trading in Far East), as the greasers would cut them up to sell these ashore for scrap. I was going to have to machine a new bushing for the exhaust rocker arm, and I might as well make one for the inlet valve rocker as well.
I was mighty relieved that I didn’t need to make a new valve insert as didn’t carry any phosphor bronze bar, however I would have made this from the brass bar or even mild steel, leaving plenty of stem clearance and it would have got us going again.
I told the chief the good news as we trotted off to breakfast and a few hours sleep. I had expected a bawling out for not ordering the spares but he just thanked me, gave me and the Junior a couple of cold beers from his fridge, and said he would inform head office.
I was just drifting off to sleep when the Chief came into my cabin and said Head Office wanted to know how to stop this happening on their other ships. I had already thought about this and I was going to wire the oil control valve to supply pipe in the open position. This seemed to satisfy him, and before he asked, I told him I would machine a couple of new bushes for the rocker arms. (Telling him under my breath where to go!)
He was under a lot of pressure as we had three gennys; at sea we had one running, one on standby, and one under maintenance. As we came close to port and went to standby we added another generator to the switchboard, leaving the third one on standby – as things stood we had no standby and were due in Montreal in three days time.
Machining the New Components and Rebuild Operations
On my noon to four watch, I left the Junior at the controls and went up to the workshop, picking up a bar of brass on the way.
We had a set of inside and outside micrometers which I was familiar with, so I measured the shaft and knocked the old bushes out of the rocker arms and measured the inside diameter of these, adding five thousands of an inch on the outside diameter of the bush to form an interference fit. I cut a length of the brass bar and clamped it in the lathe chuck. Well, here goes nothing; but it went surprisingly well and in no time at all I had the first bush ready to fit to the rocker arm. I knew I had forgotten something – I hadn’t put an oil groove inside the bush or drilled a supply hole.
Back to the lathe and as soon as I had the bush machined, I run a spiral groove around the inside of the bush, parted it off and drilled a wee oil supply hole right through into the groove.
Next, I knocked the bush into the rocker arm and tried it on the shaft– a little bit too tight. A quick run through with the expanding reamer did the trick. We had all the right gear, which was down to the Chief’s good selection of engine maintenance tools.
Same again for the second bush and we were ready to rebuild. I let the Junior clean up the head and rebuild the valve gear whilst I had a cup of tea and a cigarette at the controls. A few sketches of the cylinder head under repair are shown below;
We both stayed down after watch and rebuilt the genny, setting the valve tappets and reconnecting all the pipes, priming the lube-oil system ready to fire up the engine.
Well, moment of truth, we turned her over on air whilst bleeding the diesel lines, and keeping an eye on the oil supply to the rockers and away she went– no satisfaction is as great as seeing and hearing an engine you have repaired bursting into life.
Beautiful oil supply – a bit much with the control valve full open so I closed it in a few turns until there was a good supply, then wired the valve securely to the oil pipe.
I looked down from the genny platform and the Chief and Second were giving me thumbs up whilst I got splattered in oil.
I stopped the genny and jumped down beside the two of them, telling the Junior to replace the rocker-box covers.
Once this was done we fired her up again and I went to the switchboard and put the genny on line. We let her run for about an hour on load then lifted of the offending cylinder rocker box to reveal the rocker arms glistening with oil and not too hot to touch.
Well, thank you Harland and Wolff, and the City & Guilds Engineering Certificate Course. This was a mandatory part of the apprenticeship for which I had attended night school two nights a week and one full day; a part of the course was learning machining skills on the lathes and milling machines.
So ends the saga of the generator failure due to lack of oil. I was only 23 years old at the time and what a responsible job. We should always learn something from these occurrences; keep a good selection of spares and lock any manual oil control valves in their operating positions were my lessons learned.
Don’t forget; when the repairs are successfully completed; have a few cold beers to celebrate (and calm the old nerves)– Cheers!
References
- Author’s Experience
