Technical Vito W639

Technical Vito W639

Mercedes Vito (W639) Manual Mirror Replacement


This is just a quick overview on how to replace the manual drivers (or passengers) door mirror on the Mercedes Vito W639. Written below is a brief run-down on how I replaced the door mirror. Not a massively technical job, I know, but may be useful for people who are a little wary about pulling the trim off.  The first thing you need to do is to carefully remove the plastic trim (shown inside the yellow rectangle on the photo below) that runs from the front/top of the door panel and all the way up to the top leading edge of the inner door frame.

The 2 yellow dots show the approximate location of these clips. Take care when removing to protect the trim, if possible, as my trim came off and left the clips still located in the door. Fortunately, the mounting points were not badly damaged and I was able to relocate them without any problems.

Mercedes Vito W639 Manual Door Mirror Replacement 1

The 2 clips that hold the panel in place are metal spring clips and these are located into small mouldings in the trim panel itself. Images below show the top and bottom clips, respectively, after I had relocated them.

Mercedes Vito W639 Manual Door Mirror Replacement 2

Once the trim has been removed, you will now see the third mirror mounting bolt and the 2 locating holes for the clips.

Mercedes Vito W639 Manual Door Mirror Replacement 3

Remove all 3 mirror housing bolts, being careful to support the door mirror to prevent damage to the mirror, or the door.

Mercedes Vito W639 Manual Door Mirror Replacement 5

And in the traditional vein of the Haynes manual, refitting is the reverse of removal!


The above article was submitted to Mercedes Gen-In with thanks to:
Peter Johnson of ‘Enhance With Vinyl’

Sprinter Fuel Rail Pressure Regulator Problems – Poor Starting


The Mercedes CDI series of diesel engines have an electronically controlled fuel pressure regulator mounted on the end of the fuel distribution rail. This controls, as the name suggests, the fuel rail pressure. It relies on the seal made between a single small O-ring which is backed by a split fibre backing ring.  What happens over time is that the O-ring wears and often fails allowing pressurised fuel to bypass the valve and ebb away the required running pressure that the injectors need.  Often the problem becomes more noticeable once the engine is warm and poor starting results.

Usual symptoms for this can be laboured starting when warm and occasional non starting, if the fuel rail cannot maintain the required minimum of approximately 300 bar at crank to allow the injectors to fire.  If it is possible to monitor rail pressure using Live-Data, you may see the rail pressure dancing between 266 and 550 bar. Instability of pressure when holding a steady throttle will be the clue as to a problem with the fuel pressure control.  If you do not have access to a compatible code reader thankfully the repair is simple and not costly so easy and cheap to eliminate as a cause of poor warm/hot starting. (Under £10)

Sprinter fuel pressure regulator fault 1

Remove the upper section of the inlet manifold to allow access to the rear of the fuel rail, just under and against the bulkhead/firewall.  Identify the electrical connector and remove it, select a 1/4 drive socket wrench and appropriate small reverse torx socket and short extension.  Remove the two opposing pins on the regulator flange (left and right as fitted).  Pull out the fuel pressure regulator from the end of the fuel rail.

Sprinter fuel pressure regulator fault 2

Keeping the device clean, remove both the green O-ring and fibre backing ring from the tip of the regulator and replace with new components.  Refit the regulator assembly to the rail.  It makes it easier if you have the left hand threaded pin in place in the regulator flange mounting hole, before offering it into place. (left hand in fitting position, if standing at front of engine)  Once the two pins are re-fitted the electrical connector can be attached and the intake manifold upper half rebuilt.

Sprinter fuel pressure regulator fault 3

Back of the fuel rail where the regulator mounts (normally hidden from view)

It is important to note that a failing fuel injector can also deprive the fuel rail of its operating pressure. If you suspect that this is the case, perhaps after changing the regulator O-ring to find there is no difference to the fault then you must carry out or entrust a garage to do a diagnostic ‘leak-off test’ to prove the injector system is sound.  WARNING a failing fuel injector that is passing unmetered  amounts of fuel can soon damage the engine catastrophically, either through piston overheat or engine seizure and any suspected problems must be investigated promptly!  See this interesting and descriptive forum post regarding leak-off testing.

Sprinter fuel pressure regulator fault 4

Fuel rail pressure regulator seal kit part number

Mercedes Sprinter Gear Selection Cable Replacement

In this case one of the cable retainers to the Sprinter gear selector had broken away and required a new cable set to be fitted. For information a genuine new set of selector cables are approximately £100 plus vat from Mercedes Benz. Mercedes Sprinter to 2006 part number of cable assembly – A 901 260 14 38 Please note this part number is for ‘cables only’ and does not include any retaining clips for the gear selector or locking pawl adjusters on the gearbox lever arms, you would have to order these items separately if any of yours were broken or missing.

Before starting replacement work, if possible select neutral.

Mercedes Sprinter Gear Selector Cable Replacement 1

First unclip the gaiter from around the gear selector and remove the dash fixing self tapping screw beneath.  Now remove the cubby box beneath the pen holder by removing the two screws at the back and pulling it out, then remove the central dash fixing beneath, unclip the paper clip/note holder and release this hidden self tapping screw. Withdraw the plastic centre dashboard facia.  Note the position of the electrical connectors on the fitted switches behind and remove their plugs.  Disconnect the cigar lighter and LED illumination bar.  Once all electrical connectors are removed you can fully remove the panel and store it clear of the work area.

Mercedes Sprinter Gear Selector Cable Replacement 2

Remove the floor tool box lid and polystyrene foam wedge from the passenger side footwell and pull back the rubber floor covering. Undo the single fixing screw to the wrap-around console under-panel trim section on the passenger side and draw the back edge forward and out to unclip the centre join.  Once this first half is removed this reveals a central fixing that needs to be removed, along with a final single fastening on the opposing edge by the pedal-box.  Remove the remaining lower section.

Mercedes Sprinter Gear Selector Cable Replacement 3

Undo the two torx pins that hold the selector cable grommet to the floor.  Undo the two bolts that fix the gear selector to the dash frame, pull the assembly forward at the top and up-out of its retaining ears. Once released remove the spring clips from the cable retainers and unclip both the eye and ball ends of the control cables from the underside of the selector lever.  Remove the complete selector from the dash.

Mercedes Sprinter Gear Selector Cable Replacement 4

From underneath the vehicle, unclip both plastic lever cable locking pawls on the selector arms, open them up slightly to their disengaged position, being careful  not to damage them.  With a 10mm spanner and socket undo the pin and nut that secures the locking plate to the cable guide and remove it.  Slide out both cable restraints and pull the ribbed end sections of the cable inners free from the adjustment locking pawls.  From inside the cabin pull up the released control cables, threading them through the floor (two person job) and up behind the dash section to remove them.

Mercedes Sprinter Gear Selector Cable Replacement 5

Thread the new cables down through the floor, following the same route of the originals.  Offer up the selector and thread in both cables into the locator holes at its base.  Use the two steel slide fork clips to secure the cable outers by their retainers to the base of the selector assembly frame.  Clip in the cable ‘eye’ and press on the ‘ball joint’ to their relevant  levers under the selector lever.  Locate the gear selector into its lower dash locators and fold it inward, replacing the two upper fixing bolts.

Mercedes Sprinter Gear Selector Cable Replacement 6

Mercedes Sprinter Gear Selector Cable Replacement 7

Correct the cable lengths through the floor grommet and fix it in position by fastening the steel plate into the floor with its two pins.

Align the gear stick to an approximate central/neutral position, locate and push down fully the locking staple into the gear lever ball. This locks the lever in a known central ‘maintenance’ position.

Mercedes Sprinter Gear Selector Cable Replacement 8

From beneath the van, slide in the adjustment ribbed ends of the cables into the two pawls on the gearbox selector arms, once in position push the cable ‘outer jacket’ retainers into the brackets (Grey cable uppermost) and replace the locking plate.  With the gearbox in neutral, gauge the forward and backward play in gear selector arms and set the adjustment mid-way of the measured play, latching down the lever lock and pressing it firmly closed, captivating the selector cable end into the pawl type clamp on the gearbox selector arms.

Mercedes Sprinter Gear Selector Cable Replacement 9

Back inside the cab, withdraw the locking staple from the selector lever ball, latching it fully upward on its slide releasing gear lever motion.  Test gear selection.  It should be perfect, if not calculate where adjustment needs to be made and shorten or lengthen the rods underneath the vehicle using the pawl locks to obtain the desired result.

Rebuild the remaining dashboard and console in the same way as removal.



Sprinter Low Boost – Limp Home on Full Throttle

One of the 2004 long wheel base Mercedes Sprinters developed a problem where everything was fine under moderate throttle openings but once full power was called for, the van would register a fault and lock into limp home. Recycling the ignition cleared the fault, until the next wide open throttle and call for high power.

A great deal of work had been done on this particular van over a short period and most of the regular problematic contenders covered elsewhere on this subject had been dealt with. We knew we had good fuel delivery, good fuel pressure, sound boost and good induction hose-work. New sensors had been fitted on both low and high pressure points on the system and the only fault recorded was low boost.

Faulty Sprinter turbo boost actuator

We had previously seen another fleet operators Sprinter register low boost and discovered that the intake air filter was completely choked with muck and grime, this was not the case with this van.

Examining for mechanical issues became a primary focus as all the electrical systems were sound and cross-referring their readings on ‘live data’ proved their adequate function. In driving the vehicle with the code reader connected, we were able to see that maximum turbo boost was never achieved at full power, but was seen approaching moderate peaks at more modest and lazy throttle openings.

Often the van would perform fine unladen and fail consistently when loaded, slipping into limp home as soon as the driver tried to make good progress.

I removed the airbox and checked the vacuum pipework from the brake servo to the boost control valve and everything was in good order. I removed the supply pipe to the turbo actuator and double checked this for problems such as nicks, cuts and splits – nothing.

The lever arm to the turbo was free and this was confirmed by removing the circlip from the eye of the actuator arm and manually operating it to prove there was nothing wrong within.

Faulty turbo boost actuator Mercedes Sprinter

My next test was to push the actuator rod back into the actuator and be certain the movement was unhindered and smooth. The next test was to block the vacuum pipe opening with a finger, allowing air to be expelled while I pushed the rod inward. Closing the gap with moderate finger pressure should be enough to hold vacuum inside the diaphragm, making a ‘popping’ sound as the rod springs back to its extended position when you release your finger. I noticed the fitted actuator was not doing as it should in that respect as it was not ‘popping back’ to an extended position. Indeed, careful observation proved that the rod was moving very slowly to a fully extended position with a finger blocking the port, indicating a failure of the internal diaphragm – probably a slight leak or pin-hole.

This would under normal circumstances been difficult to spot as it had not failed completely. The actuator still pulled the turbo lever to a fully down position once the engine was started. However the small leak meant that the on-off pulse control of the actuator, given by the Pulse Width Modulation (PWM) of the vacuum control valve, was not as it should have been – resulting in under-boost on high power call situations.

The replacement of the actuator although fairly straight forward in mechanical terms, is a bit of a fiddle to accomplish, as one of the mounting bolts is a good finger-stretch into the confines of the turbo and takes some jiggling to get the pin back into position and tighten it.

There are three 10mm bolts into the exhaust side of the turbo scroll casting. These hold the actuator support bracket and also clamp the spool cartridge face against the turbo scroll casting flange making a gas tight seal.

Once these three bolts are removed and the circlip removed from the rod/lever, the actuator can be removed for inspection. Access to the area is best achieved by removing the complete air box, the turbo intake hose and brake servo vacuum pipe. Once these components have been removed, additional removing the vertical heat plate/shield that separates the air box from the turbo assembly is essential to obtain free access to the three actuator fixing bolts – especially as one is a real swine to get to!

Faulty turbo boost actuator Mercedes Sprinter 2

It is important to set the actuator arm/rod length of the replacement part to the same dimension as the original. This is critical in that it effects how the vanes are positioned within the turbo for any given actuator setting. Simply measure the new rod length to the old one and make adjustments using the 10mm lock-nut and thumbwheel provided on the actuator rod. Lock the setting once you have it and ensure the hole in the rod eye is positioned in the correct plane to accept the lever bar of the turbo once reinstalled.

Rebuild is the reverse of disassembly from this point. Once fully built, check your work and clear any remaining fault codes and then road test the vehicle. Once again boost should be available through the complete power range and it should react smoothly to engine loading, just as it did prior to the fault occurring.

Other Mercedes Sprinter turbo fault/boost related posts:

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Inside the Mercedes Sound 5 CD/Radio Unit – (Intermittent Buttons, Strange Display Behaviour)

Mercedes Sound 5 Radio Repair 1

The Mercedes Sound 5 fitted to Vito and Sprinter vans is a generally reliable unit that performs adequatley for the most part within the environment of a commercial vehicle.  There has been two manufacturers that have produced the radio, Hyundai and Becker.  Although the units are similar in function there are some physical differences to the layout and choice of internal components. Both offer similar audio features and identical connections, designed and produced in alternate factories.

There are few reported problems with either model of the Sound 5 unit, but there are a couple of common issues that crop up from time to time.

The faults: The occasional loss of display and button functionality is the most seen fault and in most cases can be easily rectified by following the procedure outline in this post.  The chassis of the Becker radio is shown in the photographs below and it comes apart in a very simple way.  First lift up and remove the upper steel cover lid by levering at the back.  Identify and remove the two torx head screws either side of the front upper chassis just behind the front panel.  Pull either side of the chassis sides outward to disconnect the latches either side of the front panel.  Lever the front down and off the chassis.

Mercedes Sound 5 Radio Repair 2

What this now reveals is the common cause of the above problems, poor connection between the chassis electronics and the front panel.  There is a row of gold contacts on the Becker made radio that mates with a sprung leaf type chassis connector strip.  This connector carries all the communications from the front panel to the micro controller mounted on the chassis PCB.  There is a multiplexed communications bus that sends and receives commands to and from the front panel, causing buttons to have actions and the display to illuminate whatever the CPU tells it.

Mercedes Sound 5 Radio Repair 3

Corrosion due to the damp (condensation) environment in which the radio lives, begins to tarnish the connections between the chassis and front panel.  The panel PCB’s plated pads take on board some discolouration / oxidisation, as do the mating tips of the sprung leaf contacts.  To maintain a good connection between the two assemblies is important, as the communication and functionality of the radio depend on it.  When these contacts become less reliable a catalogue of faults can start to appear.  These faults are usually – Buttons do not function as they should, it becomes impossible to turn off the radio, the display inverts or displays nothing, except the amber back light.  Even sometimes resetting with the ignition does not always bring back the radio to a working condition.

Mercedes Sound 5 Radio Repair 5

With the front panel face down on a soft cloth, remove all the self tapping torx screws on the rear, carefully unclip the four plastic tabs, one on each corner of the lower and upper edges.  Once the plastic back panel has been lifted off, turn over to the front and grasp the volume ring by its edges, giving it a straight pull.  The volume ring and ‘on’ button will unlatch, keep them safe.  It is now possible to remove the PCB from the button matrix mounted in the front part of the housing.

Mercedes Sound 5 Radio Repair 6

I had a damaged LCD display in the radio I was repairing, no doubt caused by someone pressing or banging the radio front to get it to display correctly.  I have tried to source spare parts from Becker and Hyundai for both models of radio and as yet have had no success getting individual LCD display parts.  What I had managed to do, was source another radio with a faulty chassis quite cheaply.  I was going to exchange the front panel PCB between the two units, as the good LCD display was housed in a case that was more worn and grubby than my own.  By changing over just the display unit in the front panel I was preserving the chassis security coding that is mated to the ECU in the vehicle.  If I had just fitted another radio, I would have had the ‘PROD’ error as described here in this post, and the radio would not have functioned.

Mercedes Sound 5 Radio Repair 7

If there had been liquid (soft drinks especially) spilled on the preset buttons at some time and they have become ‘sticky’ and do not return to their normal position – while the front panel is in pieces, it is a simple task to clean this off and have the radio working as good as new.  Once the PCB section is taken out of the front panel it can be seen that the faceplate houses some ‘rubber membrane’ push button pads.  These contact with conductive areas on the front side of the PCB allowing a button press to transmit a function to the processor.  The plastic buttons just provide a means of pushing the conductive rubber membrane against a circuit board ‘pad’.  Once the membrane is removed the buttons can also be unlatched if required and washed in mild detergent.

Mercedes Sound 5 Radio Repair 8

Simply peel back the rubber membrane in one of the three obvious active sections and push the protruding button stems back through to the front of the panel with a thumbnail, thus removing them for cleaning.  If you were to photograph the front panel before disassembly you could remove all the buttons from the facia frame and wash them all in soapy water, leaving them in a warm place to completely dry before building it back up as per your image.  If the rubber membranes are contaminated, wash these very gently, taking care not to use any solvent or abrade the conductive tip areas on the rubber pads.  Similarly, allow these to dry thoroughly before refitting and building up the front panel.

Mercedes Sound 5 Radio Repair 9

The main contact pads areas on the rear of the front PCB were cleaned using a fine cleaning rubber block (you can use a pencil eraser) until bright and shiny, the same was done to the sprung contact leaves on the main chassis, and the front panel rebuilt then fitted back to the chassis.  Be sure to latch the lower edge of the front panel under the chassis lip before folding back the front panel to its fitted, engaged position.

Fitting the two side retaining screws completes the front panel mounting.

Mercedes Sound 5 Radio Repair 10

If you wished to swap-out the CD deck, it is very easy to accomplish before refitting the front panel.  Simply undo the four screws at each corner of the deck and lift it upward.  This reveals a single ribbon cable with red connector to the main PCB.  Pull upward the connector and release the CD deck from the chassis.  A new or replacement assembly can be fitted quickly in the reverse order.

Mercedes Sound 5 Radio Repair 11

Hyundai HA1111 Sound 5 – Top Becker Sound 5 – Bottom.

The Hyundai made radio chassis has some differences from the Becker model, namely the front panel has extra function legends visible above the preset numbers and also the rear panel alloy casting is slightly different.  The photograph below shows the Hyundai HA1111 radio, with its ISO plug connected for identification.  Although the CD deck can be swapped between models, with the exception of maybe the volume control knob and a few plastic bits, that is as far as it goes with regard common parts.  The Hyundai front panel PCB contacts the chassis using pointed pins set in an offset pattern, and as such the two facias are not interchangeable.   It worth noting however that the Hyundai player suffers the same contact oxidisation issues as the Becker model and it can be cleaned and serviced in the very same way.

Mercedes Sound 5 Radio Repair 12

Becker Sound 5 – bottom radio, Hyundai Sound 5 – top radio

Quite often this simple procedure is all that is needed to recover your radio to working condition and it is well worth the simple work involved.

You can of course get to check out and test all the pixels and test the contrast of the LCD display by entering the ‘test’ mode, where you will be able to make other key adjustments and changes, for example: activating the AUX feature if required, to utilise the radios auxiliary audio input capabilities with an external MP3 player etc. See this post here.

Mercedes Sound 5 Radio Repair 14