Le Tonkinois Varnish

B & D Murkin

UK main importers for

Le Tonkinois varnish

Flexidisc sander

Disassembling the Eberspacher D2 main unit

Eberspacher Airtronic D2 & D4 service 1

Read the advisory notice at the bottom of this page before starting any work.

The heater has to be removed from the boat or vehicle for servicing.

Take care when dismounting the Eberspacher, galvanic corrosion of the alloy ports can make removal of the pipes difficult and it can weaken the ports. Photos of this are on the Faults page.

You will need a special tool to remove the glow-pin, our modified socket works beautifully.

You will also need T20 and T25 torx bits and screwdrivers.

The burner gasket and glowpin screen should always be replaced, the blower gasket can often be reused.

Servicing parts are available on Ebay, typical D2 cost 2017 £11, plus £5 for blower gasket if required.

D2 and D4 glowpins should last for the life of the heater.

Clicking on the images will display a larger better quality picture.

The Airtronic D4 heater is a higher heat version of the Airtronic D2, servicing is the same.

The Airtronic D5 heater is different, see D5 D5LC D5L servicing page.

Unscrew the four crosshead screws and remove the blower unit.

The wires fixed to the glow pin mean it cannot be removed with a standard 12 mm socket spanner.

If you are doing a full disassembly it can sometimes be removed with an open ended spanner once the blower unit has been removed but our make of spanners would not rotate enough to get to the next flat. The open ended spanner cannot used when replacing the glowpin screen without removing the blower unit.

My solution - modify a deep socket using an angle grinder to cut a slot, ideally the slot should be a little longer than shown.  The cut was later extended to make the slot about 30 mm long. Smooth any sharp edges to avoid damage to the wires. A hacksaw and file could be used instead of an angle grinder. This was a 3/8 drive deep socket (about 65 mm long), 12 mm, cost on Ebay £2.89 including postage Sep 2017.

A 1/2 inch deep drive socket would also do provided the outer wall is not too thick.

Fit the modified socket over the wires onto the glow pin, attach the socket wrench and unscrew.

Take care the wires do not catch up while unscrewing.

The D2 burner is held by 3 torx T25 bolts, but before you undo them, make sure you have a replacement burner gasket. The old gasket usually falls apart but even if it looks intact always replace it as failure can leak exhaust gasses into the circulated air.

The glow pin screen was removed at this stage but no photos were taken during its removal.

I took care not to push the screen into the burner when levering the sides inwards with a small screwdriver so it loosened and could be hooked out.

A tip from David Jerrard, he uses a 7 mm tap, a couple of turns grips but does not expand the gauze allowing it to be removed easily. Not worth buying one specially but if you have one in the toolbox it could be tried.

Replace the screen even if the old one looks clean, the small gaps between the layers can become blocked. Note that if you are only replacing the glow pin screen it can be done in situ by just removing the upper case, ECU and glowpin.

Eberspacher recommendations are to replace it every year irrespective of its condition.

The disassembled Eberspacher D2.

d2service09_big.jpg d2service10_big.jpg d2service11_big.jpg d2service12_big.jpg d2service13_big.jpg d2service14_big.jpg

Check the blower gasket. We find they are normally ok and can be reused. An Espar document says they should always be renewed. It's your decision.

d2service15_big.jpg d2service16_big.jpg d2service17_big.jpg

Fuel filter in a D1LCC pump. You may have to use a pointed implement dug into the side of the filter to remove it.

Remove the air inlet grille by turning slightly and pull off.  Try in both clockwise and anti clockwise directions.  If too tight to turn you may have to lever it off.

Removing the case and Electronic Control Unit

Remove the air outlet end cap if still fitted by inserting a small screwdriver under the case to free the pips (photos of this are on the D1LCC servicing page). Unclip and remove the upper casing.

d2service01_big.jpg d2service02_big.jpg d2service05_big.jpg d2service06_big.jpg

  The Eberspacher can now be lifted from the casing.The exhaust outlet is on the lower right.

Top view of the Eberspacher D2.

Combined Flame and Overheat sensors on right.   Glowpin middle lower.

Unplug 3 wiring connectors from the ECU.

Close up view of the ECU holding clips.

Also shows the magnet mounted in the impeller.

d2service08_big.jpg d2service07_big.jpg

Remove the torx fixing screw.

Press the holding clips inwards and remove the ECU.

d2service03_big.jpg d2service04_big.jpg

Unplug the blower motor wiring connector on the other side.

Checking the Fuel Pump Filter

The Fuel Metering Pump contains a fuel filter which should be checked and cleaned as part of the service.

The photographs are of an Eberspacher D1LCC pump, the Eberspacher Airtronic D2 pump is similar but has different connections.

fuelpump10_big.jpg fuelpump11_big.jpg fuelpump12_big.jpg fuelfilters1_big.jpg

Unscrew the 17 mm nut on the fuel pump inlet. Do not unscrew the nut at the end with the terminals.

D1LCC pump with filter removed.

Badly neglected filter with its replacement.

The condition of this filter is not normal, the filter can usually just be checked for debris and does not need to be changed.

Disassembling the Blower unit

This should not be done during a normal service, only do it if the motor has failed.

Originally we thought these were non repairable but we have now taken one apart.

Instructions are on the Blowers page.

Replacing the combined sensor

The combined sensor can be replaced without uninstalling the heater.



Remove the top cover. Remove the fixing screw and lift out the ECU. Unplug the two sensor connectors from the ECU.

The sensor is just visible here and is held in place by a metal clip. Release the end of the clip and pull the sensor out.


The replacement sensor comes with a plastic tool. The tool is not sold separately.

This disassembled unit shows the circular recess for the sensor. With the case off the sensor can easily be fitted without the tool. With the case on the recess is not visible. It is still possible to position the sensor but the tool makes fitting easier.

Lift the clip and push the sensor fully into position with the tool as shown here on a disassembled unit. Refit the end of the clip into the hole before removing the tool.


You use any information and advice we give entirely at your own risk.

If you do not accept this do not use this site, go to an Eberspacher dealer.

I have tried to make it as accurate as I can but accept no liability for errors or problems caused by following our pages.

Some of the information is only suitable for people with a good aptitude for mechanical and electrical repairs.  Any DIY involves some risk of accidents and you must decide if you are capable and can do it safely before carrying out any work.

You should also ensure your DIY is done to a professional standard in order to avoid creating potential hazards and insurance invalidation. Boat installations must strictly comply with Marine regulations.

Page 2 continues with the examination, diagnosis and reassembling

Servicing D2 D4 (2) D5 D1LCC D1L D3L Hydronic Blowers
Top ˄ Home Eberspacher < Previous Next >