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Eberspacher Fuel supply 1.
Often the only fuel related problem considered for Eberspacher problems is running out of fuel, other reasons are easily overlooked.
Eberspacher heaters use a fuel metering pump to supply tiny measured pulses of fuel to the heater. The pump is pulsed at a rate controlled by the Electronic Control unit (ECU), each time the pump pulses the solenoid makes a loud "tick" sound.
Fuel is drawn by suction from the fuel supply up to the pump.
Fuel flows into the combustion chamber where it is vaporized and mixed with air from the combustion air intake pipe and burnt.
The hot exhaust gasses pass through the inside of the heat exchanger before venting through the exhaust pipe.
It is important that pumps and fuel pipes are correctly installed as many faults can be caused by incorrect installation.
Full details are in the manuals which can be downloaded free from www.eberspacher.com/ or www.espar.com/.
Fuel types and suitability.
Fuels suitable for Eberspacher diesel heaters.
We have no expertise on fuel types so I am grateful for the specialist advice we received on suitable fuels for Eberspacher heaters.
Most fuel sold at the pumps in the UK is winterised from September onwards and therefore should be OK for winter use, untreated fuel will wax up at relatively mild temperatures.
For all fuels good housekeeping is essential, modern fuels do not store like they used to.
Road diesel - specification BS EN 590, often referred to as white diesel or Derv.
Red diesel - This is actually Gas Oil.
Before January 2011 'red diesel' was normally High Sulphur Gas Oil (also called 35 second oil, household heating oil).
This was mainly used for agricultural and off road plant.
From January 2011 fuel regulations changed so supplies now should be:
Low sulphur Gas Oil with up to 7% bio for use in all off road machinery.
Low sulphur Gas Oil with no bio fuel added, intended for use in Inland waterways and marine estuaries.
However there is no guarantee if you own a boat that you wont be supplied the 7% bio fuel.
It is now illegal to supply or use high sulphur gas oil on the inland waterways, it is still used for sea going boats.
Kerosene (Paraffin) - Premium Kerosene is known in the UK as Paraffin. Earlier manuals list paraffin and it is suitable.
Domestic central heating oil - There are two types of domestic heating oil, 28 and 35 second.
Standard Kerosene to BS2869 Class C2 is a heavier distillate than Paraffin. Also known as 28 second fuel, this is a lighter alternative to standard heating oil (Gas Oil) and burns much more cleanly with low sulphur content.
We are now running our own Eberspachers on 28 second fuel, it burns cleanly with virtually instantaneous starting even in cold conditions. We found a hardware store in Bridgnorth that stocked it, rural garages could also be worth checking.
35 second oil is High Sulphur Gas Oil as mentioned above. In Germany it is sold as Heating oil EL.
Biodiesel.
Biodiesel, also called FAME (fatty-acid methyl ester), is made from animal fats or vegetable oils.
The table below shows Eberspacher bio diesel compatibility, if you are unsure about suitability do not use bio fuel.
There are no problems using red diesel or gas oil but you may still find old forum articles describing problems.
The causes were investigated and solved in the Eberspacher technical report bulletin mentioned earlier.
Essentially Eberspachers will run on all of the fuels described provided there are no other issues.
Pump Mounting.
Eberspacher recommend mounting the pump between 15 and 35 degrees from horizontal with the outlet higher than the inlet.
If the pump is below 15 degrees it may trap air bubbles and supply less fuel so usually fit it at about 30 degrees to allow for vehicles parking on a slope or for boats to tilt from horizontal.
The pump can also be mounted vertically, the amount of fuel pumped will be a few percent more so do a fuel quantity check to confirm it is still within specification.
Water in diesel fuel.
Diesel fuel will always contain some water when sold. As the fuel level or temperature changes air enters the tank through the vent, condensation then forms when the air cools increasing the water in the tank.
The water– fuel interface at the tank bottom is an environment that encourages biological growth which can clog filters and prevent fuel flow to the heater.
Diesel floats on top of water so pickup pipes should not reach the bottom of the tank.
If water is found in the fuel siphon it off from the lowest point of the tank until clear fuel is siphoned up.
Fuel Degradation.
Diesel fuel starts to deteriorate the moment it leaves the refinery. As it ages during storage, it creates particles and a black sludge that accumulate in the tank. The diesel visibly darkens.
Debris can be disturbed when new fuel is added or when fuel sloshes around in the tank.
The cetane value of the fuel also drops as it ages and can drop so low it will no longer ignite in the heater.
More information is in the Eberspacher technical bulletin 281, click here to view.
Priming the fuel supply
If the fuel pipes are empty the pump has to purge the air from them before fuel can reach the heater. With a thin pipe this often takes two start attempts, with a larger or far longer pipe it can take 5 or more restarts and up to 30 minutes to start.
Manual priming by dabbing temporary wires on a battery can be done but it can take a lot of pulses. As a comparison we estimate one start attempt on a D1LC can give over 300 pulses. An alternative idea is to use a car trafficator relay to pulse the pump.
Cold weather.
Fuel thickens as the temperature drops, if it combines with debris in the fuel filter it can restrict the fuel flow.
Any water trapped in the pump or filter can freeze and block the fuel feed and seize up the pump.
Water can be trapped in the exhaust pipe and freeze which blocks the exhaust gas flow. This can be a problem on boats where the outlet pipe is higher than the heater so condensation cannot drain. Also water may enter the exhaust from the outlet, either when the boat keels over or in large waves.
Some fuels do not perform well at low temperatures.
Fuel flow and Air leaks.
With transparent fuel pipe tiny air bubbles are usually visible in the fuel as it pulses towards the heater which can be a very useful diagnostic check on fuel flow. These bubbles are created by the pump action and are present even if there are no air leaks.
If more bubbles than those shown in the picture are present it indicates an air leak.
Larger bubbles can be due to a serious air leak but are usually caused by lack of fuel
The small quantity of fuel used means small air leaks in the pipe before the pump can reduce the amount of fuel pumped.
The pipe is under suction so no fuel will leak out to indicate problems. Leaks in the pipe after the pump can also be a problem.
Usual causes are holes in the rubber connecting pipes or badly sealed joints. If the rubber connecting pipe is leaking renew it together with the clamps, just tightening the bolts is often unreliable and the fault reappears.
We have found clamps have to be very tight to give a good seal but don't overtighten and sheer the bolts.
Too large internal diameter pipes can also give poor seals.
Pump.
Fuel pumps come in 12v and 24v versions as well as several different supply rates including 1 - 3 kW and 3.1 - 5 kW.
I originally expected any Eberspacher 1 - 3 kW pump to be interchangeable but Eberspacher say the pumps are adjusted during manufacture for each model. Our tests confirm this is the case. The D2 and D4 use the same pump which is marked 1 - 4 kW. Diesel and Petrol heaters use the same pumps. The fuel inlet is at the end furthest from the electrical terminals.
Testing and disassembly details are on Eber Fuel Supply 2 page.
Fuel filter.
Unscrew the 17mm nut on the fuel pump inlet.
More fuel filter pictures are on Eber Service 2.
Badly neglected filter with its replacement.
In most services the filter can be cleaned and does not need to be changed.
If the fuel filter in the pump inlet is clogged it will restrict the fuel flow causing non starting or flame-outs.
It may need a pointed implement dug sideways into the plastic just inside the filter to lever it out.
If the filter clogs regularly remove it completely and fit a small external fuel filter.
Do not unscrew the other nut at the end closest to the terminals as the spring is very easily lost. Also it can alter the fuel rate.
Fuel quantity test.
The fuel quantity test is an important check of the quantity of fuel delivered to the Eberspacher.
Do this test if you suspect a fuel problem.
It checks for blocked fuel filter, blocked or kinked pipes, loose connections, air leaks, faulty pump, or incorrectly installed piping.
If the pump does not deliver sufficient fuel it can cause difficulty starting, flame-outs and white smoke.
Too much fuel can cause black smoke and the heater to carbon up.
Details of the test are on Eber Fuel Supply 2 page.
Normal air bubbles in fuel pipe are very small.
More tiny bubbles indicate a small air leak.
Larger bubbles indicate an air leak or lack of fuel.
Fuel pipes and pickup.
There are restrictions on teeing from the existing engine fuel supply pipes, read the Eberspacher manuals carefully.
There is one statement in some of the Eberspacher installation manuals about gravity feeding that is not fully explained and so could be misunderstood. Gravity feeding to the pump is ok, gravity feeding without a pump is not allowed.
If the heater takes fuel from the main tank a separate fuel pickup pipe is normally used. The end of the pickup tube should be cut so it is between 1 and 4 inches short of the tank bottom. This ensures there will be enough fuel left to run the engine and prevents water and crud in the bottom of the tank from being picked up.
Users may not realise the heater can run out of fuel with fuel still remaining in the tank and think the heater has a fault.
If the pickup pipe is too large or long the fuel may trickle back.
Large diameter fuel pipes can cause several problems including not priming the pipes, non starting and flame-outs.
Blockages can occur in the pipes but are most likely at the pickup or in the filter.
Carbon build up can obstruct the fuel flow where it enters onto the glow-plug screen.
Eberspacher fuel pipe from the pump to the Eberspacher is hard clear plastic, 4mm outer and 1.5mm or 2mm internal diameter. Maximum height lift for a D2 from the pump to the Eberspacher is 6 feet 6 inches. The pipe from the pump to the fuel tank is black hard plastic 5mm outer and 2mm internal diameter. Maximum height lift from the bottom of the tank to the pump is 2 feet 6 inches.
The proper Eberspacher fuel pipe is difficult to kink or compress. Do not use cheaper soft plastic pipe which can kink badly.
Where pipes are joined they should butt against each other inside the rubber connecting piece, gaps can trap air bubbles.
Marine installations must comply with all regulations and use metal pipes. Try to keep pipe lengths short to reduce priming time.
Soft pipe kinks easily blocking the supply.
Flame-outs.
If insufficient fuel reaches the Eberspacher the flame will extinguish and the flame-out causes the heater to shut down.
The most common reasons for restricted fuel flow are blocked fuel filter, kinked pipe, air leaks, air lock or running out of fuel.
Water in the fuel collects in the bottom of the tank, as this sloshes about it can be picked up replacing the fuel.
Unsuitable fuel can cause flame-outs at low temperature particularly at the lowest heat setting.
Note flame-outs can also be caused by a clogged glowplug screen, blocked breather hole, heavy carbon deposits as well as blockages in the combustion air flow or exhaust.
Older pump from my Eberspacher D1LCC.
Airtronic D2 and D4 pump.
General.
Note 1 Suitable for operation with FAME according DIN EN 14214 in flowing capable condition.
Fuel thickens when temperature drops below 0°C.
Note 2 Operation of the heater with up to 10% more biodiesel added to the manufactured road diesel without restriction is possible,
ie heater can work with about 20% total.
We think the D1LC compact heater group should also be marked with Note 2, it was missing on the copy we obtained.
The instructions given in the AIRTRONIC D4 manual below probably also apply to any of the models capable of using Biodiesel.
Operation of heater with mixtures greater than 10% is restricted during periods of temperatures below 0°C.
Vent hole must be cleaned every 500 hours (twice a heating season assuming 1000 hours of operation annually).
Atomizing Screen must be replaced every 500 hours.
Heater must be run for 30 min on high heat with regular diesel fuel once every 500 hours if mixtures above 50% are used.
When using 100% biodiesel, the heater should be operated twice a year with diesel fuel (in the middle and at the end of a heating period) to burn off PME deposits. Let the vehicle tank run almost empty and fill with diesel fuel without any biodiesel. While running on this tank filling, switch the heater on 2 to 3 times for 30 minutes at a time at the highest temperature setting.
Biodiesel produces about 10% less heat per litre than normal diesel and poor oxidation stability means additives may be needed to improve storage conditions.
Biodiesel is an excellent medium for microbial growth which is accelerated by water so special care must be taken to remove water from fuel storage tanks to avoid sediment buildup, premature filter clogging or storage tank corrosion.
Diesel engines & heaters that are not designed for biodiesel can suffer from filter clogging, coking and rubber seal damage.
Home made or roadside bio fuels are very different to EN 14214 spec oil.
Fuels not recommended for Eberspacher heaters.
Supermarket vegetable oil (New or Used frying oil) unless properly processed into FAME.
Fuels mixed with used oil.
The amount of money saved on these fuels will be insignificant compared to your additional servicing and repair costs.
Heater Model
|
Heater-No
|
100% FAME Operation
Note 1
|
Operation with road diesel which currently contains
10 to 12 % Biodiesel
|
AIRTRONIC D2 / D2 Camper
|
25 2069 05 00 00 /
25 2326 05 00 00
|
No
|
Yes Note 2
|
AIRTRONIC D4 12V / D4 24V
|
25 2113 05 00 00 /
25 2114 05 00 00
|
Yes
|
Yes Note 2
|
AIRTRONIC D4S 12V / D4S 24V
|
25 2144 05 00 00 /
25 2145 05 00 00
|
Yes
|
Yes Note 2
|
AIRTRONIC D5 12V / D5 24V
|
25 2361 05 00 00 /
25 2362 05 00 00
|
Yes
|
Yes Note 2
|
AIRTRONIC D3 Camper / D4 Camper /
D4 Camper plus
|
25 2317 05 00 00 /
25 2318 05 00 00 /
25 2327 05 00 00
|
Yes
|
Yes Note 2
|
HYDRONIC
D4WSC/D4WS/D5WSC/D5WS 12V
|
All versions
|
No
|
Yes Note 2
|
HYDRONIC D 5 W S 24 Volt (!)
|
25 2146 05 00 00 /
25 2218 05 00 00
|
Yes
|
Yes Note 2
|
HYDRONIC 10 / D 9 W
|
All versions
|
No
|
Yes
|
HYDRONIC 16/24/30/35
|
All versions
|
No
|
Yes
|
Air heaters D1LC compact /
D3LC compact / D3LP compact / D5LC
|
All versions
|
Yes
|
Yes,
probably also Note 2
|
Air heater D8 L C
|
All versions
|
No
|
Yes
|