TDI PD Element Leaks: Fix with New Seals & Head Gasket?

Hello,
It's a bit of a frustrating story about my 2004 Touran with a 1.9 TDI engine (engine code AVQ).

During the second timing belt replacement, I had the Piezo injectors (PD elements) refurbished. In exchange, I received new ones with the same part number, but with new nozzles and new seals. During the timing belt replacement, the camshaft, hydraulic lifters, and rocker arm shafts were also replaced (due to scoring on the camshaft, noticeable wear on the bearing shells, and signs of use on the lifters). So far, everything seemed good, however, the Piezo injectors apparently weren't sealing properly afterwards. According to VCDS in the idle speed control, all the values were at least +/- 1.5, with one being as high as 2.99 mg/H.
Okay, so I removed the components and found that both of the upper black seals were broken. I installed new seals, and there were clear signs of wear on the cylinder head where the PD elements sit. I removed the burrs from these areas using sandpaper. After reassembling the (of course, new) expansion screws, the threads of the retaining screws for the PD elements stripped, and the screws came out of the cylinder head. Helicoil didn't really work.
Okay, so I've got everything now. I managed to find a used cylinder head where the injector seats have sleeves installed.
"This one was installed and fits well, but the PD elements probably aren't sealing properly, even though new seals were used again. It vibrates slightly at idle, runs relatively roughly, and the fuel consumption at idle (without any other loads) is about 1.2 liters per hour. Previously, it was 0.5-0.6 liters per hour."
The twist angle is ideally at 0.0 degrees, but occasionally it's at -0.5 degrees.
MWB13 shows the following (warm engine, no consumers active):
Cylinder 1: -3.01 mg/h
Cylinder 2 - 1.11 mg/hour.
Cylinder 3: 2.99 mg/hour.
Cylinder 4: 1.34 mg/hour.
The values are even worse.
Now the question is what's causing it. The company that refurbished the PD elements believes that dirt from the installation of the PD elements and pieces of the defective seals may have migrated into the PD elements, preventing them from functioning correctly. They want to verschandeln the elements again and re-test them. Both the old PD elements and the "new" refurbished ones show signs of being installed in the ZK (likely referring to a specific component or system).
Are it possible to find reasonably priced, refurbished PD elements, or should I just bite the bullet and buy new ones?

The vehicle is otherwise in excellent condition. The transmission, clutch, and dual-mass flywheel have been replaced, and I would like to continue driving it for some time.



Thank you for your tips and experiences!

Hello Soundchef,
"I experienced similar problems with my ASZ engine. Based on my experience, the seating of the piezo elements in the cylinder head happens relatively early. I don't think it affects the piezo elements themselves, but rather the cylinder head. If your new head has revised piezo element seats, then the problem is likely to be with the elements themselves, provided that the dimensions of the sleeves match the original exactly. In my old engine, the seating of the piezo elements had also progressed quite far. I generously removed and smoothed out the burr and obtained larger O-rings. The company "HUG" (please Google them) offers O-rings that are slightly thicker than the originals. Since "HUG" also offers small quantities, I ordered a small assortment of different rings with slightly different dimensions to try out. If you use O-rings that are too thick, you will hardly be able to install the piezo elements."
I hope this was helpful to you.
Good luck.

Best regards, Joachim.

Thanks, the idea with the rings is a great one!
Could you tell me what kind of products you ordered? Specifically, what materials are they made of and what sizes are available?

I will probably try it again with different PD elements. I want to avoid having to constantly take them out and put them back in. } I can't handle any more stripped threads. }

Quote:

I can't stand stripped threads again icon_rolleyes.gif

To experiment and test, it's sufficient to tighten the tensioner screws by 90 degrees .

I would also like to try swapping PDE number 3 and PDE number 4 and see if the +2.99 mg/h value follows along. If it does, then that particular PDE is likely the main culprit.

Good evening.

"First, I measured the original Bosch O-rings using a caliper, but I no longer have those measurements."

Based on my measurements, I ordered the following item numbers at that time:

Precision O-ring, 12.80 x 2.40 mm, FPM75 material.
No. 42601280240 (Seal at the nozzle tip).
Precision O-ring, 26.64 x 2.62 mm, FPM75 material.
No. 42602664262 (top casting).
Precision O-ring, 25.30 x 2.40 mm, FPM75 material.
No. 42602530240 (Center Casting)

HUG does not offer a selection of O-rings for PDs (presumably referring to Power Distribution units).
All items are individual pieces. The quantity is as you order. Sometimes, I've had to gently tap the PDs (with a wooden buffer) during installation to help them seat properly. They then fit very tightly. To remove them, you definitely need a good removal tool. Good luck!

Great, thanks a lot!


What are your current values for the idle speed control, specifically in module MWB13?
Currently, I'm noticing that I'm lacking a bit of energy/performance.

Unfortunately, I'm just a hobbyist and don't have any software available. If I get stuck, I need to ask for help. In any case, my engine runs very smoothly, even at idle.
I can't say exactly how much the idling fuel consumption is. The display shows 0.6-0.7 liters at idle. Two of my PD (Pumpe-Düse) injectors have now reached 470,000 km, one has about 230,000 km, and one has 80,000 km. If one fails, I'll replace it with an original part from a salvage yard with low mileage. Overall, it's very fuel-efficient (if necessary, it can achieve less than 5 liters per 100 km) and still as fast as it should be.

Thank you for the tip!

I now have a refurbished cylinder head with liners installed in the bores for the PD injectors. I've also fitted four "new" (remanufactured by Bosch/VW without any signs of previous use on the housing) PD injectors. Initially, one of them was causing problems, so I replaced it and used thicker gaskets. Now the engine is running quite well.
Attached is a short log of my trip; from the marked point onwards, I had clear passage.
What do the data look like for you? Does this seem appropriate for new glow plugs in a motor (1.9 TDI AVQ engine) with 250,000 km on it?

Hello,

The values for the idle speed control are okay; however, these values are only meaningful when the engine is idling.

Best regards, Rainer.

Okay, great.

Is there anything else I should check? The fuel consumption at idle sometimes reads 0.5 liters per hour, and other times it's 0.7 liters per hour, even when no other accessories are running (lights, air conditioning, etc., all turned off).
Where does that come from?
Are there any other ideas on how to make the engine run more smoothly?