There are many causes of starting problems with the VW T4 2.5TDi. The starting point is always to check the pump timing. You can do this either using a dial gauge or using VAGCOM (VCDS) and the TDi-timing graph.
In my case, the engine started well during warmer weather and the pump timing was correct. However, when the temperature dropped to below 10°C it became intermittent to start. Upon investigation I discovered that there was no 12V getting to the glow plugs. You will have to remove the front grill and lift the radiators into the service position to gain access to one of the glow plug connectors so that you can measure the supply getting to them.
I could feel the glow plug relay (103) clicking when the ignition was switched on. Pushing on the relay in different directions resulted in 12V arriving at the glow plugs. I therefore knew that there was a connection problem.
Pulling the relay out of the fuse panel revealed the contacts to the 2 large current carrying terminals. Using a small jeweller's screwdriver I found that the 2 pairs of terminals in the vertical slot could be moved easily. However, the 2 pairs in the horizontal slot could not be moved. I suspect that the heat generated at this terminal resulted in the contacts melting into the plastic. I used a small drill bit to make a couple of slots in the plastic above the contacts. I then used a small screwdriver and a hammer to break the contacts free of the plastic. I pushed the contacts so as to close the gap. I did the same to the top pair to make sure that they were also free to move.
There are some pictures of people taking the whole fuse box apart and then using some pliers to squeeze the contacts together. Whilst this is probably a better solution it comes with some level of risk.
16 окт 2024
