Renegade_Master
Well-Known Member
Called engine technos, what are the dangerous things to look out for in an oil analysis? Would lead worry you?
Oil analysis
- Thread starter Renegade_Master
- Start date
sarabande
Well-Known Member
You're using lead (tinned) bearings ?
CalicoJack
Well-Known Member
I have just paid for this service and am not impressed. The analysis said that all was well, however.......
I needed to have the gear box removed and discovered that the endfloat on the crankshaft was in excess of the manufatures margins. On stripping down the engine (Perkins 4108) we discovered that the thrust bearings were worn and that the main bearings had begun to suffer as a result of the crank being able to move. There were deposits of swarf in the sump, but these had not been picked up by the analysis. Had we not by chance, discovered the end float we could have written the engine off
I needed to have the gear box removed and discovered that the endfloat on the crankshaft was in excess of the manufatures margins. On stripping down the engine (Perkins 4108) we discovered that the thrust bearings were worn and that the main bearings had begun to suffer as a result of the crank being able to move. There were deposits of swarf in the sump, but these had not been picked up by the analysis. Had we not by chance, discovered the end float we could have written the engine off
MoodySabre
Well-Known Member
I bought a boat in the spring and asked the surveyor if it was worth doing. He said that it wasn't because the oil had been changed. I guess it might tell you something if there had been plenty of usage of the oil. Sounds like a very small part of a large picture.
andy_wilson
Well-Known Member
The dangerous things to look for are unusual spikes in the long term pattern of analysis, taken over a number of service cycles, when compared to a sample of the base oil stock issued from the outset.
You asked about Lead, which is an indicator of bearing wear.
Normal Lead levels in completely used oil (ie service due as per schedule) from a diesel engine would be in the range 5 to 30 parts per million. Normal Aluminium levels would be 4 to 15 ppm, and high levels of these in combination would point to excessive bearing wear caused by poor lubrication.
Presence of Silicon (dirt) accompanying this would suggest that this contamination is the cause of wear due to poor air filtration.
Another cause could be coolant in the oil, indicated by coolant additives Silicon, Sodium, Boron and Chromium.
Final cause could be fuel and / or soot contamination caused by poor or incomplete combustion. A poor injector can dribble or spray instead of 'mist', and faulty injection pump or timing can have the same effect. The fuel charge burns poorly and diesel and carbon (soot) is washed down the cylinder walls and into the oil. Excessive diesel dilutes the oil, excessive soot depletes the oil additive pack, thickens the oil and can lead to oil depletion at the bearing surface causing excess wear. In this latter case high levels of Iron (cylinder / liners), Chromium and Molybdenum (piston rings) may accompany, as well as positive flash test for high concentrations of fuel, and a high % soot content.
As I said, you asked about Lead.
On it's own high lead readings mean nothing. In combination with high readings of other elements in certain combinations, or contamination from coolant or fuel constituents, a diagnosis can be suggested.
However, to repeat, these readings need to be viewed in comparison with the composition of the base oil stock, and previous scheduled samples, to be of real value.
Here are a few real life examples form oil sampled at sceduled service time.
Volvo Penta 2002 yacht auxilliary (18hp), 17 yrs old, 6000+ hrs, Pb between 11 and 36 ppm (normal, good for age of engine)
Vauhall 2.0l Tdi 140K miles, Pb 59 ppm (highi, but OK for age of motor).
BMW 2.5l turbo 25K miles, (extended service interval oil), Pb 5 ppm (low, but oil worn out and additive pack exhausted due to normal, long service interval).
Yanmar 4JH2 yacht auxilliary, 159 hrs (new!), top end seized due to coolant contamination, Pb 15 ppm (normal).
Given the cost of oil and cost of engines, worn oil is a bad thing, my 5 Series gets an interim change as the oil is not good enough for the scheduled interval, despite the claims.
I could go on, but we'll stick on Lead!
You asked about Lead, which is an indicator of bearing wear.
Normal Lead levels in completely used oil (ie service due as per schedule) from a diesel engine would be in the range 5 to 30 parts per million. Normal Aluminium levels would be 4 to 15 ppm, and high levels of these in combination would point to excessive bearing wear caused by poor lubrication.
Presence of Silicon (dirt) accompanying this would suggest that this contamination is the cause of wear due to poor air filtration.
Another cause could be coolant in the oil, indicated by coolant additives Silicon, Sodium, Boron and Chromium.
Final cause could be fuel and / or soot contamination caused by poor or incomplete combustion. A poor injector can dribble or spray instead of 'mist', and faulty injection pump or timing can have the same effect. The fuel charge burns poorly and diesel and carbon (soot) is washed down the cylinder walls and into the oil. Excessive diesel dilutes the oil, excessive soot depletes the oil additive pack, thickens the oil and can lead to oil depletion at the bearing surface causing excess wear. In this latter case high levels of Iron (cylinder / liners), Chromium and Molybdenum (piston rings) may accompany, as well as positive flash test for high concentrations of fuel, and a high % soot content.
As I said, you asked about Lead.
On it's own high lead readings mean nothing. In combination with high readings of other elements in certain combinations, or contamination from coolant or fuel constituents, a diagnosis can be suggested.
However, to repeat, these readings need to be viewed in comparison with the composition of the base oil stock, and previous scheduled samples, to be of real value.
Here are a few real life examples form oil sampled at sceduled service time.
Volvo Penta 2002 yacht auxilliary (18hp), 17 yrs old, 6000+ hrs, Pb between 11 and 36 ppm (normal, good for age of engine)
Vauhall 2.0l Tdi 140K miles, Pb 59 ppm (highi, but OK for age of motor).
BMW 2.5l turbo 25K miles, (extended service interval oil), Pb 5 ppm (low, but oil worn out and additive pack exhausted due to normal, long service interval).
Yanmar 4JH2 yacht auxilliary, 159 hrs (new!), top end seized due to coolant contamination, Pb 15 ppm (normal).
Given the cost of oil and cost of engines, worn oil is a bad thing, my 5 Series gets an interim change as the oil is not good enough for the scheduled interval, despite the claims.
I could go on, but we'll stick on Lead!
alex_rogers
Well-Known Member
Having just taken a high speed taxi ride through Germnay in a Mercedes with 450,000 km on the clock, and a warning sign indicating that it was 80,000 km past its last service interval, I'm inclined to believe that we worry too much about this.
I'd suggest that unless such analysis is done regularly and detailed records are kept in order to record what is normal behaviour, then it is totally unnecessary for a sail boat (and probably not even if all this is done). It'll lead you to change parts that would never have failed anyway, and will not avoid failures. How many engine failures in sailing yachts are caused by the main bearing giving out compared to the failure of batteries, electronics or ancillary parts? I'd suspect that the one's that do fail were showing more obvious signs of engine wear before they failed (i.e. smoking like demons).
When I used to work offshore in the North Sea, I was glad that the chopper's oil recieved this attention. However, I wouldn't spend my own money to test the oil of a yacht's engine.
Spend the money on more frequent oil changes and you'll probably have more impact on engine life. Alternatively, spending the money on an advanced or defensive driving course will contribute a great deal more to your personal safety.
I'd suggest that unless such analysis is done regularly and detailed records are kept in order to record what is normal behaviour, then it is totally unnecessary for a sail boat (and probably not even if all this is done). It'll lead you to change parts that would never have failed anyway, and will not avoid failures. How many engine failures in sailing yachts are caused by the main bearing giving out compared to the failure of batteries, electronics or ancillary parts? I'd suspect that the one's that do fail were showing more obvious signs of engine wear before they failed (i.e. smoking like demons).
When I used to work offshore in the North Sea, I was glad that the chopper's oil recieved this attention. However, I wouldn't spend my own money to test the oil of a yacht's engine.
Spend the money on more frequent oil changes and you'll probably have more impact on engine life. Alternatively, spending the money on an advanced or defensive driving course will contribute a great deal more to your personal safety.
William_H
Well-Known Member
Agree there is a world of difference between the criticality of a helicopter engine or gearbox than that of your car or boat. olewill
Renegade_Master
Well-Known Member
Hi Andy thanks a lot for the info. By the way folks we are not talking tiny yacht engines these are two TAMD 122D 485hp volvos.
The report shows high soot and some chrome. Will get the detailed coloured print out today
The report shows high soot and some chrome. Will get the detailed coloured print out today
alex_rogers
Well-Known Member
Yes, I was really responding to CalicoJack rather than your original query.
