Airscrew
Well-Known Member
I have an engine that appears to be increasingly showing a symptom, and want to work carefully through the potential culprits before opening my wallet to a suitable engineer.
Have you come across this before??
MD11c in a Centaur. Yes I have read almost everything on this forum about MD11s.
I understand from previous owner that the engine was a 'swap-in', with unknown hours, but was fully refurbed in c2010, bores, valves, heads etc. It has been regularly and fully serviced since then, including a new impeller each year, with maybe 30 hours per year since then.
I expect there will be a host of people that will say get rid of it and buy a Beta 14 or 20. OK, I accept that some people would ditch and buy new. But until it totally destroys itself, I would prefer to keep it going as a project as a classic/semi classic engine and yacht. However, I am not going to throw alot of money at it, so I am hopefully looking in this forum for keen and experienced advocated of maintenance of older diesel engines.
The symptom is a 'white' exhaust. I wont call it smoke or steam at this point. I will let you help me consider.
I understand from previous owner that it has done this since the refurb. The injectors were checked and set, but did not change the symptom at that time, and the owner ran the engine like this for 5 years without problem.
We have had the boat for 3 years, and this 'symptom has increased this year. The visible 'volume' of this white exhaust was about the volume of a small pedal bin liner. A little more on colder days, and more on higher revs (normal would be 1500-1800, higher for us is 2000, and it will open up to 22-2300 under load). The volume last week is now double that, and double again under load, enough to give some visible concern to onlookers(!). So yes it has deteriorated more in the last 4 months than in the last 8 years.
The engine appears to have reasonable compression, but I suspect not great. I haven't had it tested, but it is very difficult to turn with the handle or flywheel, but that is subjective, and I have no meaningful comparison for a baseline. (Yes, the MD11 does have 'valve lifter' levers).
Starting is reasonable, usually after 5 seconds or so. It has a manual 'cold start', which is almost always needed from cold, and occasional 'user error' might mean that I over fuel it, and it might take 10 or 15 seconds and than also a puff of black smoke. Certainly not instant as with a modern marine diesel, but I dont know what to expect from a 'good' 40 year old MD11.
From stone cold, there is a small amount of blue smoke lasting only seconds and then it is gone.
This 'white exhaust' appears to rise and dissipate, rather than sink onto the water, so I was thinking steam, and to others at some club it certainly gives the appearance of steam. Engine temps have been stable, but I first looked into the cooling.
Last winter I ran various fluids through the system, and did remove some crud. I took off the exhaust elbow and manifold, and gave them a through clean on the workbench. I would say the elbow only needed a little cleaning, and the elbow and exhaust manifold are in great shape. The thermostat works perfectly to spec.
I bought a digital thermometer, and the exhaust manifold / thermostat housing is around 65-70, pretty much as expected. There was only 5' difference between the 2 cylinders, so no evidence of a major problem in only one cylinder.
Prior to all this, I measured the coolant flow rate at around 3 litres per minute (at 1000 fast idle) and now 4 litres per minute. So some improvement, and (I think) little to worry about on the cooling side.
So, (if you are still with me!), what about fuel and oil.
On collecting and measuring the water in a bucket, I would say there is some evidence of fuel on the surface, that blue rainbow sheen you might see on a petrol station forecourt. But minimal. There were also a couple of black blobs, two or three and less than 1mm in dia. But I dont know wether that is oil or soot.
Fuel consumption is normal at around 2 litres per hour, but very difficult to measure accurately to be a meaningful measure.
Oil consumption was around .25 litres for each of the last two years, and does not appear to be higher part way through this year.
So, my dear forum friends, here is the question.
Is it a water, or fuel, or oil problem?
In my head right now, it is not 100% clear.
And the engine works 'fine', as in not broken. So I am looking at some investigation over the winter. But rather than throwing it over to an expensive engineer to perform the investigation, where to I start?
What underlying problem will cause a 'white exhaust'?
Fuel pump?
fuel pressure?
Injectors?
Valves/guides?
Rings?
Head gasket? (there are absolutely no external signs of any problem anywhere)
Or possibly an 'internal block leak'?
Alternatively,
do you know of a rock solid diesel engineer in the Solent area, ideally with very grey hair, who can diagnose it by eye and fix it with a hammer and gaffer tape in exchange for a couple of pints???
Have you come across this before??
MD11c in a Centaur. Yes I have read almost everything on this forum about MD11s.
I understand from previous owner that the engine was a 'swap-in', with unknown hours, but was fully refurbed in c2010, bores, valves, heads etc. It has been regularly and fully serviced since then, including a new impeller each year, with maybe 30 hours per year since then.
I expect there will be a host of people that will say get rid of it and buy a Beta 14 or 20. OK, I accept that some people would ditch and buy new. But until it totally destroys itself, I would prefer to keep it going as a project as a classic/semi classic engine and yacht. However, I am not going to throw alot of money at it, so I am hopefully looking in this forum for keen and experienced advocated of maintenance of older diesel engines.
The symptom is a 'white' exhaust. I wont call it smoke or steam at this point. I will let you help me consider.
I understand from previous owner that it has done this since the refurb. The injectors were checked and set, but did not change the symptom at that time, and the owner ran the engine like this for 5 years without problem.
We have had the boat for 3 years, and this 'symptom has increased this year. The visible 'volume' of this white exhaust was about the volume of a small pedal bin liner. A little more on colder days, and more on higher revs (normal would be 1500-1800, higher for us is 2000, and it will open up to 22-2300 under load). The volume last week is now double that, and double again under load, enough to give some visible concern to onlookers(!). So yes it has deteriorated more in the last 4 months than in the last 8 years.
The engine appears to have reasonable compression, but I suspect not great. I haven't had it tested, but it is very difficult to turn with the handle or flywheel, but that is subjective, and I have no meaningful comparison for a baseline. (Yes, the MD11 does have 'valve lifter' levers).
Starting is reasonable, usually after 5 seconds or so. It has a manual 'cold start', which is almost always needed from cold, and occasional 'user error' might mean that I over fuel it, and it might take 10 or 15 seconds and than also a puff of black smoke. Certainly not instant as with a modern marine diesel, but I dont know what to expect from a 'good' 40 year old MD11.
From stone cold, there is a small amount of blue smoke lasting only seconds and then it is gone.
This 'white exhaust' appears to rise and dissipate, rather than sink onto the water, so I was thinking steam, and to others at some club it certainly gives the appearance of steam. Engine temps have been stable, but I first looked into the cooling.
Last winter I ran various fluids through the system, and did remove some crud. I took off the exhaust elbow and manifold, and gave them a through clean on the workbench. I would say the elbow only needed a little cleaning, and the elbow and exhaust manifold are in great shape. The thermostat works perfectly to spec.
I bought a digital thermometer, and the exhaust manifold / thermostat housing is around 65-70, pretty much as expected. There was only 5' difference between the 2 cylinders, so no evidence of a major problem in only one cylinder.
Prior to all this, I measured the coolant flow rate at around 3 litres per minute (at 1000 fast idle) and now 4 litres per minute. So some improvement, and (I think) little to worry about on the cooling side.
So, (if you are still with me!), what about fuel and oil.
On collecting and measuring the water in a bucket, I would say there is some evidence of fuel on the surface, that blue rainbow sheen you might see on a petrol station forecourt. But minimal. There were also a couple of black blobs, two or three and less than 1mm in dia. But I dont know wether that is oil or soot.
Fuel consumption is normal at around 2 litres per hour, but very difficult to measure accurately to be a meaningful measure.
Oil consumption was around .25 litres for each of the last two years, and does not appear to be higher part way through this year.
So, my dear forum friends, here is the question.
Is it a water, or fuel, or oil problem?
In my head right now, it is not 100% clear.
And the engine works 'fine', as in not broken. So I am looking at some investigation over the winter. But rather than throwing it over to an expensive engineer to perform the investigation, where to I start?
What underlying problem will cause a 'white exhaust'?
Fuel pump?
fuel pressure?
Injectors?
Valves/guides?
Rings?
Head gasket? (there are absolutely no external signs of any problem anywhere)
Or possibly an 'internal block leak'?
Alternatively,
do you know of a rock solid diesel engineer in the Solent area, ideally with very grey hair, who can diagnose it by eye and fix it with a hammer and gaffer tape in exchange for a couple of pints???
