VW Transporter T4 Common Problems

[vc_row][vc_column width=”2/3″][vc_column_text]VW Transporter T4 Common Problems. Things to look out for when buying a VW T4.[/vc_column_text][vc_column_text]

Door Lock Problems

A common problem with the T4 central locking is the breaking of the spring in the lock. The lock button when unlocked door in the top holds the position. Without intact spring, the locking knob for light vibrations (eg. the actuation of the door handle back down) ‘fall’, which leads to a locking of all doors over the central leads.

Operation

If this happens, you can manage to repair it, that one of the locking button to open the door clings, or that one to open the door first with the central locking and then unlocking the boot and the knob opens the door locked.

Unfortunately, this spring is not available as spare parts. So if you want an original spring must complete the castle get at VW. You can use the pen but by a self bebastelte spring (eg from a ballpoint pen or the pen of a key ring) to replace it.

Installation instructions:[/vc_column_text][vc_column_text] [/vc_column_text][vc_column_text]

Spring

The spring is factory from 1 mm thick spring steel. It has about 1.5 turns, which are the ends of V-shape. The bent parts, which are used to fix the castle, have a length of about 5 mm.

Because for the spring at the mounting sufficient space available to, the mass can be varied in a replica rather generously. It is primarily to ensure that the spring is not thick, so that it between the moving parts of the castle still has game. The following picture shows one of a pen of a key ring made of spring with a diameter of about 13 mm.

Repair

Notes:

  • For the first exchange the remains of the broken spring can be removed completely. It should take particular care to, that no parts get jammed in the lock mechanism.
  • Region of the spring grease after installation.

Tools:

  • Various pliers for manufacturing and installation of the spring
  • Screwdriver

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Things to look out for when buying a VW T4

[/vc_column_text][vc_column_text]VW Transporter T4 Common Problems.[/vc_column_text][vc_column_text] [/vc_column_text][vc_column_text]

Suspension/steering

If you are experiencing uneven tyre wear it could be down to several factors, or a mixture of a few! If the van has been lowered, this in its self could put the steering geometry out and a 4 wheel alignment check should confirm this. Worn suspension bushes are another factor to consider. Knocks or clunks on rough road surfaces will usually indicate worn bottom or top ball joints, drop links or anti-roll bar bushes.

Brakes

While there are no real problems so to speak of on the T4, a regular brake check over of the hydraulic pipes and hoses, brake pads, brake discs etc. should keep everything in tip top condition. If the van pulls to one side or another whilst driving this could be a sign of lack of maintenance. The rear caliper sliders can also become seized up and could result in the sliders snapping in the calipers when trying to correct.

The rear handbrake cables can let water in over time and in really cold weather freeze up and make your hand brake feel like its stuck on!! New rear hand brake cables will cure this, the front hand brake cable can wear and fray/snap over time and again should be replaced as and when needed,

The only other thing to note is that the brake vac pumps (2.5TDI) can wear and cause a possibly alarming tapping/knocking noise from the engine. This is simply diagnosed by depressing the brake pedal and if the noise quiets down you know a new brake vac pump is required.

Instrument Cluster

Oil light flashing and beeping. Although this could be initially be a worrying light to see flashing on your T4, don’t panic. This fault is usually down to an alternator and or wiring issue (blue wire). The oil pressure warning system is quite an over complicated affair which uses low and high engine speeds (worked out from the alternator) and low and high oil pressure sensors on the engine!

Bellow if a copy of the checks procedure as written by Penbryn and posted on the VW T4 forum which is a very good write up to get to the bottom of this problem

Why are there so many oil pressure warning problems on VW vehicles?

As usual VW has designed an overly-complex solution to a relatively simple problem – oil pressure monitoring. Because of the complexity of the DOP system, it has led to lots of problems with the system itself rather than real oil pressure issues. Although it has to be said that such is the unreliability of DOP, that real oil pressure problems are sometimes ignored based upon the assumption that it is a ‘wiring fault’ or indeed vice-versa. It should be noted that VW abandoned DOP on later vehicles after about 2000/2001, and also on later (1999 onwards) 2.5TDi T4’s. So if you have a problem with oil pressure on one of these it is likely to be oil pressure sensor, wiring or an actual mechanical problem.[/vc_column_text][vc_column_text] [/vc_column_text][vc_column_text]

So what is DOP?

VAG vehicles have been using the DOP (dynamic oil pressure warning) system since the 1980’s, this means that two oil pressure switches and engine RPM are used to determine oil pressure rather than the system of a single switch.

The VW rationale behind the DOP system is that low oil pressure problems are typical of high-mileage VAG engines with worn bearings and oil that is hot (and thin). The combination of thin oil and worn main bearings means that the oil pressure is marginal at lower RPM where the oil pump is not spinning as fast at idle speeds as it does when driving.

In order to address this perceived problem, the system basically monitors the low pressure sensor when the engine is below 2000 rpm and the high pressure sensor above 2000 RPM. This is done via the instrument panel which uses the ‘w’ terminal on the alternator to measure engine RPM and two switches – one on the head – It is normally closed and opens at (I think) ~0.3 bar ..

and one on the oil filter housing – this is normally open and closes at a fairly high pressure depending on engine type (1.4 bar for normally aspirated diesels and some TDs, and 1.9 bar for MK3 tdi (again – I think))…

Diagnosing faults with the DOP system

The instrument cluster only monitors the oil filter housing sensor when the engine is over 1800 – 2000RPM and if this sensor is not switched by 1800-2000 RPM the oil buzzer will sound and the oil pressure light will also flash. The body of the sensor is typically white, grey, or black in colour and is connected to the wiring harness with a yellow wire.

A. To test the high pressure sensor circuit and wiring (sensor for this is on the oil filter housing):

1. Disconnect the wire to the high pressure sensor on the filter housing and let it float (un-connected).
2. The oil buzzer should now come on and indicator will flash when the van engine speed is above 2000 RPM.
3. Now connect the yellow wire to ground and rev the engine past 2000 RPM… the buzzer should not sound at all.
4. If you fail either of these tests you have sensor issues, wiring, alternator wiring, or instrument cluster issues.

To test the sensor itself:
A test light between the sensor and the positive battery terminal should be ‘off’ at warm idle and come ‘on’ as you rev to 1800-2k RPM, if the sensor on the flange is working properly. If the buzzer still sounds with the wire to the sensor grounded the problem is most likely the wiring to the instrument cluster.

B. To test the low pressure sensor (sensor for this is on the cylinder head): 

1. Disconnect the wire to the sensor and leave it float.
2. Connect a test light between +12V batt and the sensor.
2. Start the van and leave it idle – the light should go off – if it doesn’t the you have a faulty sensor.
3. If it does and the oil light is still flashing then you have either a wiring fault or the engine speed signal from the alternator is missing.

So, the long and short is:

A flashing oil light, on its own at engine speeds of <2k RPM is a function of the low pressure sensor on the cyl. head. If the indicator stops flashing at engine speeds over 2k RPM then you should look at the low pressure sensor and associated wiring.

 

A flashing oil light and buzzer are both a function of the high-pressure sensor on the filter housing. If this is happening you should look at the high pressure sensor and associated wiring.

 

The high pressure sensor on the oil filter flange is only monitored when the engine is running at or over 1800-2000 RPM.

 

A flashing oil light at all engine speeds (and without buzzer above 2k RPM) is indicative of a missing engine speed signal (alternator ‘w’ terminal) – check to make sure that the instrument cluster is getting the correct engine speed signal from the w terminal of the alternator.

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