The answer lies in the oil!
By Mike Hunter
Boating New Zealand Magazine
Issue # 162 February 2000
The commercial sector of the marine industry, particularly shipping, has long recognised the value of using engine oil as a diagnostic tool to check out the health of the engine - sort of like a blood test on humans and a lot less expensive than pulling the whole motor to bits.
The oil analysis detects traces of various metals which indicate degradation taking place in the engine, and detects contamination of the oil quality reserves which in turn gives an indication of the oils performance and its useful life.
Every engine, regardless of its size, has the common elements of iron, copper, lead, aluminium, chromium, silicon, sodium and tin as part of its manufacture. Through use or abuse of the engine these elements can break down, in minute quantities, to be transported around inside the engine by its lubricating oil.
The presence of these elements in the oil can mean the following:
- iron: wear from the camshaft and piston bores
- copper: wear from bearings and bushes and contamination from oil coolers
- lead: white metal component deteriorating - bearings
- aluminium: piston wear
- chromium: valve stems and top rings
- silicon: dirt; sump gasket attached with silicon- a no no!
- sodium: salt, or glycol antifreeze contamination
- tin: white metal breakdown - bearings
Problems with engines on two of his commercial vessels have alerted one Auckland charter skipper to the benefits of oil analysis. With one engine being stripped down after it overheated and then stopped working and the other being closely monitored until its next 100-hour oil change, the analyses of used oil samples have proved extremely accurate.
On some of the superyachts in Auckland at the moment Hieatt may take as many as eight samples from the various engines in use on board. Here he performs his oil doctor role in the engine room of one of the visitors.
Case One
The charter boat had been slipped for her annual survey, expected to take three weeks. The haul out time extended to three months as extra work was found necessary but because the long-term dry storage was unexpected, no steps were taken to prepare the engine for its long stay on the hard.
When the boat went back in the water, the owner changed the oil, ran the engine and had an oil taken sample for diagnostic analysis to make sure everything was in order. This particular engine had twice had oil analyses done but the third, by a Wellington laboratory, gave great cause for alarm.
The report featured alert codes for high aluminium, high chromium, high copper, high iron, and high sodium.
Once he recovered from his initial shock, the shaking owner realised that when the boat was slipped, at least one exhaust valve would have stayed open, probably an inlet valve as well, and for three months they sucked in the salty, dirty, dusty environment they were sitting in, contaminating at least one cylinder in the engine.
The owner realised he should have "winterised" the engine by removing the injectors, squirting in a lot of oil and turning the engine over on the starter to squirt the oil mixed with the incoming diesel right through all the nooks and crannies of the engine, fogging it with lubricant, and preserving it from the ravages of the fresh sea air.
Because he didn't, the salt air got into the engine, and began to oxidise the iron bore of at least one cylinder. Once the engine was re-started the pistons were going up and down over this rust zone, wearing the chrome (rings), the bore (iron), aluminium (pistons) - a little each revolution, and dropping the scrapings into the oil.
As a result of the analysis the alert was sounded but the owner has reserved his decision until the next analysis is done.
"The experts would say we have seized one piston," says the owner, "but you've got to think what's happened. The engine is running okay to the ear. That's my interpretation and if the next sample shows all the alerts drop then my theory is correct. And OK we have one cylinder which is down on compression - we checked that - but we think we have the answers for those readings."
The diagnostic service includes a report on each engine, with recommendations. In this case the analysis showed a "marked, if not alarming, increase in the wear metals from the top of the engine. These increases included alerts on iron, aluminium, and chromium".
The report from Marine Diagnostic Service Ltd also showed an increase to the level of warning on soot, which may relate to the wear-metal increases. Even though the last two reports have shown a couple of alerts, they had remained consistent. The alerts shown gave the impression that one of the cylinders had dropped a ring or something of similar nature.
"The alert on copper is lower than in the last report and is probably not of major importance. The level of sodium had increased to a level where it had drawn an alert. Again, there was little or no water shown and the glycol was negative so the sodium can only be the residue of the salt environment."
The recommendations were:
1. Call your marine engineer immediately to make further investigations.
2. Check the air filtration system for any points where salt air may get in.
The report ended: "I know this is not the best news at this time of the year but the increase in the wear-metal count left me with only one option and that was to inform you. By further investigation I hope that this report may have prevented a possible engine failure."
According to Kelvin Hieatt of Marine Diagnostics Ltd "the engine is on its way out - but hey it's not going to die now! Just bring the oil changes back from every 300 hours to every 150 hours, and help keep the quality of the oil as high as possible. This will extend the life of the engine. The next sample will hopefully show that everything is back in line, and that it was just a lubricating and fitting the engine back into work problem caused by sitting unprepared on the hard."
Hieatt works with the owner of all the boats he samples to respond to the easiest and cheapest way to remedy the alerts his samples have shown. The presence of soot is a sign of problems with the fuel supply or showing the engine is not breathing properly. Hieatt says blow by, when the engine's rings are almost shot, is one of "the hardest things to tell an owner".
Usually the advice to the owner is to check for over fuelling which can be done relatively cheaply by checking the injectors, re-seating them or fitting new nozzles, and taking a look at the fuel pump.
"A rebuild is the last thing an owner wants to hear. Obviously we try to eliminate the smaller problems first".
Sequence #
3 2 1 Oil in use 1330 DMX DMX Laboratory # 991208.056 990326.036 961203.029 Ticket # B11978 A89623 A79203 Date Sampled 07/12/99 25/03/99 01/12/98 Date Received 08/12/99 26/03/99 03/12/99 Oil Service hrs/km 309 237 281 Oil Used - Litres 4 1 4 Total Engine hrs/km 816 - 1081 Oil Changed? Yes - No Viscosity 40°C (cSt) 115 115 102 Diesel Dilution, GLC (%Wt) n/a n/a n/a Soot Index (IR) +1.7 1.3 0.7 Water, dispersed (% Vol) 0.04 0.02 0.07 Oxidation (Abs/cm) 17 12 10 Glycol Antifreeze (IR) Negative Negative Negative Metal Analysis
Iron (mg/l) *110 64 48 Copper (mg/l) *16 *28 *67 Lead (mg/l) 2 1 3 Aluminium (mg/l) *81 8 6 Chromium (mg/l) *54 +9 +10 Silicon (mg/l) 10 8 10 Sodium (mg/l) *64 +14 6 Tin (mg/l) 14 7 14 Comment:
Alert Codes: High Aluminium, High Chromium, High Copper, High Iron, High Sodium
Case Two
The same owner also had a medium-sized ferry working on the Waitemata harbour, which had also rung alarm bells in the lab. This engine had been having almost monthly oil changes and sampling at 253 to 346 oil service hours
The soot index had slowly climbed, signifying "blow by" or worn rings, but the oxidation was the rapid riser. The problem was so serious the engine had to be removed and replaced with a new one at the height of the season.
The Marine Diagnostic report from Kelvin Hieatt was unswerving in its recommendations:
"As you know we have received the sixth set of reports back from the lab for the oil samples drawn from your vessel's engines and gen set:
Port engine: As you can see from the reports there are still no warnings or alerts on the wear metal analysis. However, the viscosity and soot are still high, but this time both have only drawn warnings rather than alerts. The hours are longer (346 hrs) and the injectors have been serviced. Hopefully the work carried out during the time ashore will assist even further.
Starboard engine: Well what can I say? Although the oxidation level did not pull a warning it was not far from doing so. The level is the highest it has been since starting the analysis program and what it shows is that the oil has been heated up at some stage.
As usual the viscosity and soot have both pulled alerts, however this time, like the oxidation, they are the highest they have been since starting the program. As this engine has continually drawn warnings and alerts for viscosity and soot it would appear that the answer could be a little deeper that the fuel problem we first thought. It is hard to know which one of the three reasons high soot can be blamed on: excessive blow-by, overloading or over fuelling. Definitely the injectors are the easiest and correct place to start due to cost.
I know you were keen to see if any wear-metal showed up, but as you know, nothing more than the usual did. Wear-metals will not always show up in a case like this as the engine may have bedded itself back in after it was cooked the first time. The over-heating that took place a week or two before the engine started to blow oil may have been the last straw and lead to a weakening in the rings. I know that there has been a lot of discussion as to why this engine died and that the oil analysis program did not foresee it, but I'm afraid an overheating problem to this extent is something the program is unable to detect or forecast. If by chance when the engine is pulled down there is an opportunity for me to see the ring gear as it comes out this would be much appreciated, as it would assist in the further development of my knowledge of your engines."
Gen set engine: The gen set remains clear of any signs of degradation at 377 hours. This is an excellent result as it confirms that the gen set is free of the diesel problem that showed up in the first sample. It is also starting to confirm the length of service the oil is capable of and that servicing it at the same time as the main engines is fine.
Our recommendations for the port engine are as follows:
1. That at 300 hrs we undertake another sample so as to monitor the effects of the work done and the warnings shown on soot and viscosity.
Our recommendations for the starboard engine [new] are as follows:
2. That you consider dropping your oil service hours back on this engine due to its youth and the rebuild it has had, to say 150 hrs. This would allow the bedding in material to be diluted from the oil and thus from the engine.
3. At this time it would be good to take a sample to monitor the engine as it beds itself in.
These two rather dramatic examples show what extent oil analysis can help in the preventative maintenance program on any boat, and since their inception just over a year ago the Marine Diagnostics team has steadily increased its workload from the recreational boat sector.
There are three phases in the reports after analysis:
1. Normal - self explanatory
2. Warning - the lab report detects some irregularities which need to be watched carefully.
3. Alert - further investigation is needed and its possible some remedial work is needed, ie injectors
Analysis can show contaminants like diesel, soot, water ,salt (Sodium),in the oil, which can be quite a problem in a lot of cases. Oxidation, another contaminant, is caused by either overheating or the over use of the oil.
With many recreational boats doing only 100 to 150 hours a year some owners ignore the need for oil changes and some form of maintenance over the winter months. However case one advises against this.
Recreational boats may take longer to establish a pattern of engine wear through oil analysis because of their low hours of use but after three years a pattern will have emerged. The system also acts as reassurance for the prospective owner when selling the boat.
Most recreational boat owners need preventative maintenance and lubrication education - such as not leaving the oil in the motor for a couple of years before changing it. Three hundred hours is too long for a recreational boat to go without an oil change again because of their sporadic use.
Pleasure vessels should have the oil change done every 100 to 150 hours. However an analysis of the hot oil before the change can confirm or deny the need for one. The sampling can be done quickly via the oil dip tube with a lab report available within three days.
This can also determine how long it takes the engine to break down the oil, reducing its lubricating qualities. If it's an old engine, the report may have advice on how to prolong the life of the engine. If the oil after 100 hours looks and tests good, the owner may be advised to extend his test time to 200 hours. If on the other hand the engine has 300 hours time on the oil and it is beginning to show signs of degradation the owner will be advised to bring the test times back gradually to help the engine last the longest with the best lubrication service intervals.
Sampling the used oil in a powerboats engine costs $140 for the crankcase oil only- about the same as an average oil change. On a twin engined craft the cost rises to $180. If the sample analysis is to include the transmission fluids the single engine craft costs $180, while the twin engine installation and transmission the cost is $280. This cost includes the sampling, the lab analysis and the written report. By offering this personal service the company, which has been in existence for a year has a rapidly developing customer base.
A close-up of oil leaving the mid range of the sump into its sample jar. The plastic tubing from the dip stick socket is disposable, helping to ensure the quality and integrity of the sample.
Taking an oil sample
The engine is run up before Hieatt gets to the engine room, whether it is a ferry, superyacht, commercial fishing boat or 40' launch. He takes a length of 6mm clear tube, seals the end with heat, and cuts a small nick 2" up from the end. This hose is introduced into the dip tube. A small vacuum pump and sample jar are attached. The first sample is pumped from what should be the mid stream area of the engine sump. A second jar is also filled completing the sample collection. The first jar of oil is tipped back into the engine, ensuring that the sample being sent for analysis is the best representative of the oil in that engine. The tube is not re-used as it is crucial the sample is not compromised in any way.
Sample Information
Sequence #
6
5
4
3
2
1
Oil in use
DMX
DMX
DMX
DMX
DMX
DMX
Laboratory #
991118.031
991012.079
990907.039
990810.025
990713.023
990615.032
Ticket #
B09172
B15262
B02735
B02732
B05701
B01726
Date Sampled
17/11/99
10/10/99
04/09/99
06/08/99
09/07/99
11/06/99
Date Received
18/11/99
12/10/99
07/09/99
10/08/99
13/07/99
15/06/99
Oil Service hrs
346
328
246
253
278
283
Oil Used - Litres
11
5.3
3.6
4.8
-
3
Total Engine hrs
5263
4918
4356
4352
4099
3821
Oil Changed?
-
Yes
Yes
Yes
Yes
Yes
Oil Analysis
Viscosity 40°C (cSt)
*140
*138
+128
*138
116
+132
Diesel Dilution, GLC (%Wt)
n/a
n/a
n/a
n/a
n/a
n/a
Soot Index (IR)
*3.8
*3
+ 2.1
+ 2.7
1.6
+ 2
Water, dispersed (% Vol)
0.05
0.02
0.02
0.02
0
0
Oxidation (Abs/cm)
9
4
2
6
1
1
TBN(ASTM D2896) (mgKOH/g)
8.4
8.9
9.4
8.9
8.9
8.7
Metal Analysis
Iron (mg/l)
40
40
35
62
37
49
Copper (mg/l)
1
2
1
3
1
1
Lead (mg/l)
1
1
2
2
1
1
Aluminium (mg/l)
2
2
1
2
1
2
Chromium (mg/l)
1
1
1
2
1
1
Silicon (mg/l)
7
7
6
6
8
9
Sodium (mg/l)
0
0
0
5
0
1
Tin (mg/l)
2
3
2
0
2
2
Comment:
Alert Codes: High Aluminium, High Chromium, High Copper, High Iron, High Sodium
