Bob Senter on John Deere and Lugger

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Bob Senter on John Deere and Lugger

Postby Georgs » Sun Feb 14, 2010 10:13 am

Lucas+and+Bob+Senter.jpg (31.35 KiB) Viewed 7677 times

That's Bob Senter shown at right.

Original posted by John Marshall on Nordhavn Owners Group on Yahoo:

I've collected the text from a number of Bob Senter posts on various forums and put them all here. Bob really should write a book, or at the least, a comprehensive magazine article.

It's been my observation that you can find a thousand posts across the Net, and many magazine articles, many written by supposed experts, and I always get the feeling from reading those posts or articles that diesel fuel contamination management is a bit like anchoring... an art versus a science and the subject of many opinions. Either that or its like those infomercials where all you have to do fix your life is to buy their product (additive, filtering system, Vegamatic, Rocna, etc.)

With our gigantic tanks, we Nordhavn owners face special concerns with aging fuel unless we're using our boats a LOT. Especially since some of our boats, like the N55/N60, ride so much better when they are carrying half-full or greater tanks.

Bob brings us back to ground and reminds us that science and simplicity often go hand in hand. As always, I can't thank Bob enough for his support, especially in cutting through the BS that often gathers around various marine topics.

Here are some related bits of wisdom from other Bob Senter posts in different forums I belong to... you might want to archive this email, as its full of good advice:

1) How to determine what is plugging up your filters by analysis of filter bowl contents:

"How to tell what's in the tank:

Thanks for mentioning OLD fuel. Everyone who has attended Captains Classes at the (John Deere) factory and a few of my seminars probably remembers my rant about the shelf life of diesel fuel: it's about 90 days. Sometime after 90 days of storage, the fuel begins to form "asphaltenes", sticky black tar-like particles - you'll see them in your Racors. Commercial boats and over the road trucks never have a problem with this because they turn over all their fuel long before it gets old. Asphaltene particles stick to the sides and bottom of the tanks and trap particulates in the fuel that are normally suspended and trapped at the primary filter. When the going gets rough, the asphaltenes begin to wash off the insides of the tanks and work their way through the fuel system, eventually plugging the filters.

How do you tell the difference between asphaltenes from old fuel, dirt or microbial infestations (algae)?

Collect a black particle from the Racor and put a drop of acetone or lacquer thinner on it; if it begins to melt, it is an asphaltene particle from old, degraded fuel. Microbial particles smell bad; they emit sulfur hydroxide, the rotten egg smell. An anti-microbial (like Bio-Bor) will take care of that problem. It is much rarer than asphaltenes, though.

What can you do about it?

A high quality fuel additive will first STABILIZE the fuel so that it doesn't degrade. It will also slowly melt and clean up the remaining asphalenes - this is really important. It needs to happen gradually, not overnight, so follow the dosing instructions religiously. There are probably other excellent brands on the market (and a lot more snake oil) than the ones I've mentioned, but I don't have the documentation and track records. John Deere blesses and repackages "Stanadyne Performance Fuel Conditioner" under their own label. It is available at many diesel fuel injection shops and some marine engine parts outlets. Shop for competitive prices on the net - half gallon sizes are the easiest to handle and store. It you can't find that brand, you might consider "Power Service - Diesel Kleen". Surprisingly, Wal-Mart usually stocks it. It's been around a while, even before Stanadyne's additive, and is excellent.

If you can control the asphaltene formation or use your fuel quickly enough to turn it over in less than 90 days, that will dramatically reduce or eliminate the need for tank cleaning and the hassle of a commercial "polishing" service."

2) Topic of diesel shelf life and changes with the general availability of Ultra Low Sulfur fuels:

"You're right on the shelf life issues with the fuel, although the
problem has more to do with catalytic cracking at the refineries than
whether the fuel's sulfur content. Cat cracking increases the yield of
diesel per barrel of crude but adds an atom to the end of the fuel
molecule chain, making it unstable. Hydro-treating (injecting hydrogen
gas into hot crude gas) strips the sulfur from the fuel but also has
the unintended consequence of stripping away some of the fuel's
lubricity. Unfortunately, that's all that lubricates the expensive
fuel system parts in your diesels that are fit to about three
millionths of an inch clearance (3 microns). Fuel refineries restore
some but usually not all of the lost lubricity. There is an industry
standard (SAE) lubricity spec but getting that from the refineries is
equivalent to finding Bin Laden. A fuel analysis can provide it, but
it costs an extra $125.

Hence, the recommendations on fuel storage and additive practices.

Although an engine will run OK on Standadyne Performance fuel
conditioner, there IS an ugly downside to overdosing - this applies to
the additives, too. Good fuel conditioner is formulated to coalesce
virtually invisible entrained water into smaller drops that can be
pumped to the Racor sumps, where the heavier water will settle,
allowing the operator to drain it before large quantities puddle in
the tanks. If you overdose (typically, it takes double doses) the
water will be emulsified, passing THROUGH the primary and secondary
filter media and rusting the fuel injection components when the engine
is shut down. I was involved in replacing a fuel injection pump on a
fairly new boat that died in Ensenada because of that issue. The owner
was double dosing with Racor additive. I still have the handfull of
rusty fuel injection pump parts for Captains Classes."

3) Primary fuel filters:

"The primary and secondary filters should be changed at MINIMUM once a year - the hours are irrelevant because the filter media softens with age and can fail.

> > So, what happens at high vacuum and why does Lugger Bob get so worked up about it?
> > 1) Every engine manufacturer recommends 30 micron Racor primary elements, although 10 micron will work almost as well. Apart from the obvious dirty fuel related fuel injection system failures (caused by collapsed filter media), running with 2 micron elements ......or running with high vacuum just to see where the pain threshold is, will eventually rip the diaphragm in the fuel lift/transfer pump, depositing the contents of your tank into the engine lube oil. If you're lucky, the engine will quit, alerting you to the possibility something might be amiss. Well, that and the overflowing dipstick. Most people don't carry a spare transfer pump. (In such an emergency, you could rig a workaround by bypassing the transfer pump with a hose section and pressurizing the fuel manifold with your electric low pressure pump.)
> > 2) If you have an electronic engine like a L1066T, the DE-10 Stanadyne FI pump is incredibly forgiving and will run pretty well until its internal vane transfer pump can't pull any more fuel or collapses the secondary filter element (if it's old and soft) and gobbles up the debris formerly living in the filter. That is usually terminal.
> > 3) *If you have a L1276 engine, it will forgive all of this and simply stop when no more fuel is available. The Racor primary may or may not collapse. Before it does, you will have been receiving a steady audible alarm, warning light and error message on the Powerview telling you the fuel pressure is low.
> > 4) *If you have a JD 6108 HPCR engine, it will probably collapse the primary Racor fuel filter element, give you warnings of low fuel rail pressure and quit.
> > * These engines have positive displacement gear type transfer pumps which don't rip like a diaphragm pump but that can collapse the Racor filter element.
> > 5) If you have a L6414, LP668 or similar mechanical fuel system engine with a Stanadyne or Lucas fuel injection pump, you will also begin burn more fuel without any other symptom as the low transfer pump pressure (due to the restriction exceeding 5") causes the hydraulic light load advance to stop working. This will dramatically reduce your cruising range. When the restriction is high enough to completely defeat the hydraulic advance, you'll see white smoke in the exhaust and the engine may misfire. Electronic Stanadyne DE-10 pumps don't have mechanical advance mechanisms - the engine computer does that and it's advance program is immune to fuel pressure related problems."

4) Checking fuel system vacuum at WOT to ensure maximum filter flow during the check:

> > "The Walbro pump can't hurt the polishing filters unless they get old and soggy. Everyone should run up their mains to WOT at least 5 minutes once a day, anyway. That should be enough to see the trend. Most Lugger engines' total fuel flow is about 27 - 35 gallons per hour at WOT. Re the vacuum gauge, the restrictor will work fine - don't worry about the 'exponential' fuel curve. It's actually linear, but the restriction curve is exponential. Racor has some interesting graphs on their website showing that.
> > A JD 6108 flows 113 gallons per hour at WOT, for comparison."

5) General fuel system practices and concerns on clogging up secondary (on-engine) filters:

> > "1. Run 30 micron elements in your dual Racors.
> > 2. Run the engine to WOT and check restriction more often if you have any level of discomfort with the fuel or filters.
> > 3. You can buy a remote restriction or fuel differential pressure gauge/warning device visible at the helm if that would help.
> > 4. The secondary filter will usually last at least 100 hours if the primary did not physically fail. That usually is enough time to schedule the change while not under way. Secondary filters are far more forgiving than primaries because they operate with a double differential: the transfer/lift pump supplies about 5 PSI pressure to the secondary and the fuel injection high pressure pump has a vane transfer pump pulling fuel through the secondary element. Loaded secondary filters seldom stop the engine. They usually limit power."

6) Biodiesel:

> > "This is an issue with higher percentages (20%+) of bio-diesel, owing to its strong solvent properties. High percentages have caused extensive lacquering and seizure of injectors, piston rings and valves on some engines. (I have extensive data from John Deere if you want to read it - just email me offline.) Bio-diesel has a MUCH shorter shelf life than conventional diesel and some tough cold weather issues, making it a bad choice for any boat except a commercial vessel that burns all the fuel in a few days and operates in a warm climate."

7) Changing of filters:

> > "The following applies to LP 445, LP668, L1064 and L1066T engines (ed. although the Racor info is common to all).

> > The Racors are the PRIMARIES on your boat. How to change the Racor filters:
> > If you have full tanks, you can gravity feed and refill the fuel to the Racors when you change them, or you can use your electric pump to pressurize the fuel manifold.
> > 1. Turn OFF the engine fuel supply (temporarily).
> > 2. Have 2 new 30 micron Racor elements ready and large ziploc bags or trash bags handy to dispose of the old filters. Make sure you have a container that will fit under the Racor bowls to drain some sediment and water.
> > 3. Drain about 1/2 cup of fuel from the first Racor's bowl - if you loosen the top T handle a little, it will drain easily. Otherwise, vacuum might prevent much fuel from coming out. Turn OFF the drain valve or reinstall the drain plug.
> > 4. Remove the T handle and lid and gently remove the O-rings. Don't use a sharp screwdriver or you may gouge the seal surface and cause an air or fuel leak.
> > 5. Grab the handles on top of the element, raise it to the top and let it drain into the reservoir for about 10 - 15 seconds. Then, put the old dirty filter into the plastic bag.
> > 6. Take the new filter out of the plastic wrap and be careful not to lose the O-rings that come with it. Gently push the new filter down into the housing until it seats.
> > 7. Lubricate the O-rings with engine oil from the dipstick. Roll the red silicone O-ring over the threads of the T-handle until it seats in the groove. Gently press the big O-ring into the groove in the lid. Use a small (not sharp) screwdriver to remove any twists in the O-rings. Put the T-handle back in the lid.
> > 8. Open the fuel supply valve until the fuel level rises even with the top of the filter housing. If the tanks are low, you may need to use the electric pump to pressurize the manifold. It is OK to add clean fuel from a dedicated container to fill the Racor because all of that fuel will be filtered twice before it reaches the engine.
> > 9. When the Racor is full to the brim, put the cap back on and tighten the T-handle firmly.
> > 10. Now, do the same with the second filter.

> > The SECONDARY is on the engine. It is the final filter in the line before the fuel goes to the fuel injection pump. How to change it:
> > (By the way, the time to do this in my Captains Classes is about 3 minutes for most owners.)

> > 1. Have a new filter ready to go, with the middle O-rings lubricated by engine oil. ALWAYS INSTALL SECONDARY FILTERS DRY; DO NOT PREFILL THEM ON THESE ENGINES. Have your ziploc bag ready for the old filter.
> > 2. Grab the plastic ring on the upper edge of the filter with both hands and rotate it counter clockwise (viewed from the bottom) - that means the outside edges of the retainer ring facing you will be rotating toward the transmission. There's a detent you have to overcome with some force at first, then it rotates 1/2 turn and falls straight down. The filter will stay in place. Lubricate the threaded inside part of the retainer with some silicon dielectric lube to make the job easier in the future. There is NO tool for this - it is intended to be done by hand.
> > 3. With the ring removed, pull straight down on the filter and drop it into the ziploc bag. You might want to have an oil soaker pad under the filter in case a little fuel leaks out. You should only lose about a teaspoon or less.
> > 4. Swap the drain fitting from the old filter (now in the bag) to the new filter. It's faster and handy to keep a spare drain fitting.
> > 5. If the new filter has notches on its top edge, gently push the filter against the housing and turn it until you feel the notches engage the housing, then push straight UP until it seats. Next, reinstall the plastic retainer ring and rotate it until it clicks. There will be a vertical line on the edge of the ring that aligns with the air bleed fitting (plastic plug) on the side when the ring is properly installed.
> > 6. Turn ON your fuel supply valve, open the air bleed fitting on the side of the filter housing ONE turn and FULLY stroke the hand priming lever on the side of the fuel lift/transfer pump located just ahead of the fuel filter on the block. Hold a paper towel or oil soaker cloth at the bottom of the air bleed so that when the filter is full and only fuel comes out, you won't make a big mess. When the air is removed, hand tighten the bleed fitting snugly. Recheck it again next time you do your engine room check.
> > 7. Start and run your engine at 1200 RPM for at least 5 minutes to make sure you've expelled all the air and haven't accidentally left a fuel valve in the wrong position. Much better to find out this way than while maneuvering in a fairway. "

8) Amount of fuel bypassed by various engines (discussion from N55 group):

> > "JD6081 HPCR engines pump 100% of the gear driven transfer pump
> > capacity (built into the back of the High Pressure pump) through both
> > on engine filter and returns everything to the return circuit except
> > what was burned. Most of the fuel returns from the HPCR pump lube/
> > cooling overflow and a small portion returns from the injector leakoff
> > circuit. Theoretically, the JD6081 engine can burn about 15 - 16 GPH
> > at WOT. It requires about 113 GPH maximum fuel flow from the primary
> > filter (this varies slightly with the maximum HP rating/RPM). It also
> > has the largest on engine fuel filters of the Deere family, so as some
> > owners have pointed out, it does an excellent job of polishing the
> > fuel, since all of the return fuel has been filtered to 2 microns or
> > less.

> > Lugger L1276 engines bypass approximately 20% of the fuel it filters
> > back to the return circuit. The remaining 80% recirculates to the
> > cylinder head and fuel injectors where it supplies fuel, cools and
> > lubricates them - this prolongs filter life and keeps fuel temps even.
> > A L1276 340 HP rated engine can (theoretically) burn about 15 GPH at
> > WOT; the 425 HP can burn about 18.5 - 19 GPH at WOT. The Lugger will
> > require about 30 - 32 GPH maximum flow from the primary filters at
> > full RPM.

> > For comparison, the Lugger L1066T engines (used in twin engine 55's)
> > require about 27 GPH fuel flow from the primary filters at WOT and
> > return everything they don't burn, giving them a slightly lower supply
> > and return requirement than the L1276."

John Marshall
Nordhavn 55 #20
Posts: 126
Joined: Fri Mar 06, 2009 9:16 pm
Location: Frenchman's Bay, Lake Ontario

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