T5 AXB Cold Start Issue: Leaky Hoses

Hello,

I need your help again.

My T5, manufactured in 2005 and with 278,000 km on the odometer, unfortunately has a problem with starting when cold.

"If the car has been standing overnight, and I try to start it, it starts immediately but then dies after about 1 second. Then, I have to crank the engine for 10-20 seconds, and it starts, but 'hesitantly'."

The error occurred sporadically (3 times per year) until about a week ago.
Now, every morning. But only after more than 10 hours of standing time.
Whether the STHZ was running before or not has no influence.

The glow plugs are new, which doesn't make sense since the engine is already running.
The fuel pre-pump is audibly activating when the ignition is turned on.
The knock sensor is new; I had a warm start problem about a year ago.
DiFi is new.
Fuel tank vent, OK.
Temperature readings in the MSG are all plausible.

While WFS might exhibit a similar symptom, it shouldn't allow the engine to start, or the issue wouldn't be temperature-dependent, right?

Does "air in the system" match the error pattern?
Are there any "usual suspects" in cases of AXB (sexual assault)?

Thank you for your help.

Sounds like there's air in the system.
Since the DiFi has been changed, I would guess it's the "frog" (referring to a specific component or device).
Otherwise, check the pipes.
Best regards,

Hello,

Thank you for the response.

The T5 doesn't have a frog.
I have 4 connectors on my DiFi.
That's currently my favorite as well.
Are the seals in the connections available individually?

Does the T5 have a check valve?
I haven't seen one yet.

Another question, as I can't find any reliable information about this online.
Can I access the fuel level sensor unit with the pre-lift pump without removing the fuel tank?
If the answer is no: How will the tank be decommissioned?
I think cleaning is definitely advisable given the mileage.

Regards,
Nick.

Did the symptoms appear after the filter change, or was the filter changed because of the symptoms?
The filter housing would need to have a large sealing ring, but not every connection does!
It should be used for this purpose and also replaced. Lightly lubricating it with diesel fuel prevents the seal from slipping during installation.

In my opinion, cleaning will not be necessary.

I am unable to answer further questions due to a lack of T5 functionality.

I replaced the Difi as part of the inspection at 255,000 km.
The problem first appeared after that, but only much later and very sporadically. Initially, it occurred in May 2014 at approximately 260,000 km; then, it happened two more times by December 2014.
Now, for the past week, every day.

The situation with the poetry is different from what you described.
There are only seals in the connectors.
[Edit Admin: Please only upload images for which you have the rights! Either take the photos yourself or don't upload them.]

So, it's a fuel filter with quick-connect fittings, and I haven't been able to find any compatible seals on the open market so far.
Disconnect the hose and measure the seals, then replace them with fuel-resistant ones.

There was also a recall once.
Broken screw on the fuel pump cover.

The connectors are available individually from VW and don't cost much.

By the way, these are the same connectors (the 90-degree connectors) as those used on various VP37 vehicles at the fuel sensor. Instead of replacing the entire wiring harness, you can use the T5 connector, a rubber hose, and support sleeves (because, for example, the connector is not available separately for the G4).

Quick trip to the warehouse.

Part number for 90° connector: 3D0 201 338 B.
Part number for 45° connector: 1J0 201 338 K.

Note: I find it interesting that the 45° connector has a Golf 4 part number (1J0) .

Okay, I've now replaced the two quick couplings (on the motor side).
7L6 201 338 and 1J0 201 338K.

Now, in hindsight, it would probably have been more sensible to replace both inlet connections...
Well, let's just wait and see. I've noticed that the T5 usually starts normally if you turn the ignition on and off 5 or 6 times and wait until the priming pump stops gurgling.

If it's still happening, then I'll also replace the 3D0 201 338 B part.

What kind of recall was that? Which pump is the screw breaking in?
Doppler pump or pre-charge pump? I've noticed that the tandem pump is sweating a bit more.

Thank you very much for your help.
I will report on how things progress or whether everything is now okay.

by the way:
The G4 had quick-connect couplings on the fuel sender pump assembly.

I believe it was the tandem pump with the screw you mentioned.

Best regards,

This morning, there were no problems. We can't hear the pump gurgling anymore either. It seems there was always air in the system before.
The problem seems to be solved.

I still need to take a closer look at the tandem pump. It's quite wet.

You're very welcome.

Hi,

has been confirmed today.
No more gurgling from the pump.
Smooth start.
Great.

I first cleaned the tandem pump.
It doesn't look as bad as I thought it would.
Unfortunately, I can't find a manufacturer.
I wanted to know if it might be one of the affected LUK pumps.
It has a gray lid, but there's nothing written on it. There's also nothing visible on the casing. Maybe it's just a cheap pump.

Even though it might not be relevant to the current topic:
During the test run, I noticed that the coolant temperature (G62) was already at approximately 70°C, and the temperature at the radiator outlet was already increasing. This suggests that the thermostat is opening too early. The temperature (G62) remains constant at around 73°C when the engine is idling, but then increases to 66°C at the radiator. The temperature gauge in the car shows the same value (73°C), but the indicator shows 90°C. Well, that gauge is always lying...

Could it be that this is the reason why my auxiliary heater is running constantly?
What are the prerequisites for it to run?
So far, I only know that it is active when the outside temperature is below 5°C.
But up to what temperature? I had the heating/blower turned off.

Does anyone happen to know these values?

Regards,
Nick.

nickx wrote:

Are there any "usual suspects" in cases of AXB (sexual assault)?

Hello,

Yes, as long as it gets enough power and no critical sensor is defective: PDE is leaking or integrated into the head!
If the damage isn't too severe, resealing might help (with limited success). Otherwise, a new head will be necessary.

You'll need some specialized tools for installation and removal, as the gear mechanism needs to be pre-tensioned!


SG
Alevuz.

Um, I think you're talking about the AXD or AXE, or their EU4 successors.
I don't have a 5-cylinder engine.

AXB and AXC are the 1.9-liter EU3 engines in the T5.
As far as I know, the problem of leaky positive displacement elements (PDEs) is not as common with these engines.

Regards,
Nick.

Hello,

Yes, you are right, I missed that!

Sorry for causing unnecessary alarm.

SG
Alevuz.

Okay, here's a brief concluding report.

The engine still starts without any problems.
After a day of operation, a slight gurgling sound from the pump can be heard when starting. However, this has always been the case. I may still replace the quick-connect coupling on the supply line at the filter, on the tank side.

Regarding the temperature issue:
I replaced the thermostat.
The cooler now remains cold up to 90°C.
The auxiliary heater will also stop working.

Thank you again for your help.

Regards,
Nick.