Jetta TDI not starting


#1

We have a Jetta TDI and live in CO. It is cold out this morning and the Jetta wouldn’t fire. The engine cranked and cranked but didn’t start. We had it towed to the dealership last week for this issue and they replaced the inter cooler and said this would never happen again… Well it’s back at our place 2.5 hrs from the dealership and won’t start again! Any ideas?
Note: the fuel has been treated and is 3/4 of a tank full.


#2

just how cold is it? A diesel needs glow plugs to have a few seconds to get hot before you crank the starter. And, very cold temps can thicken diesel fuel. Either the glow plugs aren’t getting hot, or the fuel isn’t getting into the cylinders.

I don’t see how replacing the inter cooler affects a “no start” problem?

If you can get the car inside a garage and get some heat in the garage, do it. This will give the motor oil a chance to heat up and thin out, as well as the diesel fuel. Hopefully it will start once it has warmed up a bit. Then you need to figure out the root problem behind the “no start” and get it fixed.

I suspect the glow plugs are not getting power for some reason and are not working.


#3

The inter cooler was freezing up and not allowing the engine to get air. There was a service bulletin about it.

It is -10 and we ran the glow plugs twice before attempting to start. We also have a diesel truck (same fuel) and no problem starting.


#4

If I owned a diesel I would install an engine block heater and use it wherever possible. Agree, the glow plugs have to work as well. Diesel fuel used in the winter does not gel, unless the temperature is something like -50. Diesel equipment is used all over the Arctic and Alaska.


#5

Yes we agree with the block heater and are planning to install one but even above 0 temps such as +10 it starts but it is a rough start. So we think there is still an issue with the car itself.


#6

MY vote is with Uncle Turbo about this being a glow plug issue. Maybe the glow plug relay is a little wonky seeing as how the glow plugs draw a lot of current. Over time that high current can burn contact points inside the relay.

What year vehicle is this? Sometimes the glow plug fuse has been known to get stupid.

Note the 40 amp fuses. The glow plugs will draw far more current than that when the key is first turned on. This is called surge current. Over time the fuse can crack in the middle and limit or prevent current from reaching the glow plugs.
Visually the crack may not even be seen as the crack is more of a razor cut. One has to pry the fuse with a pocket screwdriver and the crack will be apparent then.