Timing Belt Replacement: New & Improved!;-)

Hello everyone,

I have 10,000 km left until the timing belt on my ASV engine needs to be replaced. I've always done this myself on my gasoline engines before, and it wasn't a big deal. Now I've just read the instructions for replacing the timing belt, and it doesn't sound very encouraging. I probably should have a professional do it. But one question keeps nagging at me: Why should you loosen the four screws of the injection pump gear first? Wouldn't it be more sensible to replace the timing belt and then measure the injection timing? If that's not correct, you can still loosen or replace the screws, or am I wrong? And why would the injection timing change? Do the timing belts have such large tolerances? In any case, the ignition timing was fine after replacing the timing belt on my gasoline engine (PF). Besides, I simply find the adjustment using elongated holes in the drive wheel to be a rather primitive solution! It seems quite rudimentary to me. Wouldn't it have been better to allow the injection pump to rotate? That would probably require flexible injection lines, and that would probably be too expensive.And another question for Ulf: Do you really adjust the fuel injection timing using a multimeter? That seems a bit too simple.

mcgregg

mcgregg wrote:

And another question for Ulf: Do you really adjust the fuel injection timing using a multimeter? That seems a bit too simple. :wink: mcgregg

I don't think this is too simple; I think it's brilliantly simple.
It worked excellently in my car.

christians wrote:

mcgregg wrote: And another question for Ulf: Do you really adjust the fuel injection timing using a multimeter? That seems a bit too simple. mcgregg I don't think this is too simple; I think it's brilliantly simple. It worked excellently in my car.

That's absolutely AMAZING! It gives an old hobbyist a renewed sense of motivation.

mcgregg

Hi.

I think the diagram method was only developed to provide the "masters" in the workshops with a as simple adjustment procedure.

If you understand the purpose of the adjustment , you can also control the result during operation .
That's more important than fiddling with charts, it's more informative, and besides, all you need for that is the aforementioned multimeter.

. . . :idea:as long as the desired injection start time has not been manipulated using VAGCOM

Ulf, that's really brilliant!

However, no one has answered my question yet: Does the ignition timing always need to be readjusted after a timing belt replacement?

mcgregg

mcgregg wrote:

However, no one has answered my question yet: Does the injection timing always need to be readjusted after a timing belt replacement?

Hi.

if you remove all the gears and the pump, of course, yes .

I haven't made my first change yet, but for now, I'll install the new belt the same way I installed the old one, without making any adjustments (as much as possible).

After that, I will check the behavior of the fuel injection start-up control during operation and only make adjustments if necessary.
I can easily imagine that a new hire isn't necessarily required, because it would only make sense if the two belts were of different lengths...

Hi,

"From my experience with timing chains, I've noticed that the start of the timing is often misaligned. Even a slight amount of too much or too little tension (even with a semi-automatic tensioner) can cause the timing chain wheel to be out of alignment, even with the locating pin, and a difference of just 0.1mm can be enough. The timing belt also has manufacturing tolerances, which is why it's necessary to position the camshaft wheel in the correct position on the camshaft in diesel engines."

Best regards, Christian.

ulf wrote:

I will initially install the new belt in the same way as the old one, without making any adjustments (as much as possible).

Hi Ulf,

Of course, one can question whether the camshaft needs to be locked so precisely, especially since, with a timing belt at 90,000 km and the engine at top dead center (TDC), the locking tool probably won't even fit. I'm curious .

Best regards, Christian.

Hello,

On a Passat (year 1999) with engine code AFN, someone ('a friendly person') had replaced the timing belt. Later, I discovered that the camshaft timing was incorrect, and significantly so. After I adjusted the timing myself using a timing tool, the car ran much better. The dynamic injection...
The time verification or scheduling process serves to ensure...
the availability of the full adjustment range in the injection system.
'and is by no means unnecessary. I have noticed in several timing belt replacements that the values...'
nicht mehr stimmten und ich die ESP einstellen musste. Sure, here is the translation of the text from German to English:

'Before'
When it came to replacing the timing belt, I always used the following values.
The laptop was taken and held.

Best regards, Jürgen.

Thank you, Jürgen, for your informative post. Did I understand correctly that the camshaft sprocket can rotate on the camshaft? That would explain the effort involved with the adjustment tool. As far as I remember, the position of the camshaft sprocket relative to the camshaft on my gasoline engine (PF, 1.8L 107 hp Digifant) is determined by a notch and a corresponding pin. After buying the car used, the engine seemed a bit weak and noisy, so I checked the position of the camshaft. And indeed, it was one tooth too early. I corrected it, and the rattling from the exhaust disappeared, but unfortunately, the engine still felt reluctant to rev. This seems to be normal for the PF. And something like that is sold as a GTI.

Slowly, I'm starting to understand more about the TDI. Adjusting the injection timing using the "Ulf method" seems ingenious and foolproof. At least, if you've managed to get the timing belt installed correctly once.

mcgregg

mcgregg wrote:

Did I understand correctly that the camshaft gear can rotate on the camshaft? That, of course, explains the effort involved with the adjustment tool

.

Hi,

With the diesel engine, you lock the camshaft, then you release the wheel from the cone of the camshaft, which allows the wheel to rotate on the camshaft during belt tensioning.

"However, I first loosen the camshaft screw using only the camshaft sprocket holder (no piston at TDC!! -> remember how to return the piston to TDC!), and not the locking bar, because the loosening torque is very high. Then, I tighten the screw slightly to lock the camshaft with the locking bar... etc."

Best regards, Christian.

Hi!

I read the thread with great interest, but some uncertainties regarding the timing belt drive still remain:

Is it correct that while the camshaft gear is rotatable relative to the camshaft, the ESP gear is not rotatable relative to the ESP shaft, and the crankshaft gear is not rotatable relative to the crankshaft?

'In my opinion, it would be even simpler if all three relevant pulleys were freely rotatable when the belt is installed, while the three components (crankshaft, camshaft, and ESP) were secured against twisting by means of fixtures. This would essentially copy the timing of the old belt exactly, completely independently of the length, number of teeth, and tension of the new belt.'

I'm afraid that's wishful thinking. The drawing already shows that the ESP wheel has a spline, so it cannot be twisted. The KW wheel certainly cannot be twisted either.

But how do you prevent the KW (adjustable coilover) and ESP (stability control) from rotating relative to the fixed rear axle? I mean, even when you tighten the belt, all the wheels inevitably rotate, and therefore the ESP and KW also rotate, since they are firmly connected to the wheels?

Thank you in advance for the clarification.

Regards,
Holger.

Hi!

I just found the following external link: http://www.rasender-killer.de/usenet/zahnriemen_2/index.htm

It then became clear to me that the ESP wheel is attached to an intermediate disc and can be rotated using elongated holes. Unfortunately, my ESP wheel doesn't have the three screws and elongated holes. My ESP wheel looks exactly like the camshaft wheel in the link. If dieselmartin has uploaded my photos of the timing belt drive online, you can see them. How is the ESP wheel secured against rotation on the ESP shaft in my system? Is a cone sufficient for the long term, or is the ESP wheel not rotatable at all during the inspection, but rather fixed in a specific position using a spline?

And another silly question: How do you rotate the crankshaft? Is there still a keyway on the crankshaft timing gear at the bottom for attaching a large wrench? And how can you tell in which position the crankshaft is? For example, the manual says 'turn to TDC.' Is there a marking on the crankshaft timing gear at the bottom?

Thank you in advance for your answers.
Regards,
Holger.

Hi Holger,

SeatArosa1.7SDI wrote:

Is it correct that the camshaft wheel is rotatable relative to the camshaft, but the ESP wheel is not rotatable relative to the ESP shaft, and the driveshaft wheel is not rotatable relative to the driveshaft?

certainly

SeatArosa1.7SDI wrote:

In my opinion, it would be even simpler if all three relevant pulleys were freely rotatable when installing the belt, while the three components (engine, water pump, ESP) were secured against twisting by means. This would essentially copy the timing of the old belt 1:1, completely independently of the length, number of teeth, and tension of the new belt.

"This is constructively designed to be difficult to implement poorly: for example, the groove on the crankshaft provides a certain degree of protection in case the crankshaft bolt comes loose."

SeatArosa1.7SDI wrote:

But how does one prevent the KW (adjustable coilover) and ESP (stability control) from rotating relative to the fixed NW (narrowing)? I mean, even when you tighten the belt, all the wheels inevitably rotate, and therefore also the ESP and KW, since they are firmly connected to the wheels?

The camshaft is fixed, but not the crankshaft pulley (which is loosened beforehand with a pin). The only thing that is fixed is the ESP shaft (using a locking pin). When the belt is tensioned, the crankshaft may rotate slightly. If this happens, simply rotate it back to the top dead center (TDC) position. If the crankshaft rotates more than 5mm (measured using the TDC indicator), the belt is likely installed incorrectly between the ESP and the crankshaft.

"Therefore, before installing the belt, I rotate the crankshaft approximately 1 cm (measured using the timing mark indicator) counterclockwise. When attempting to fit the belt over the water pump pulley, I rotate the crankshaft back to the timing mark (it's fiddly work, and the belt must not slip on the crankshaft). After that, all the timing marks align."

Hi Christian!

When the belt is tightened, the crankshaft may, in some cases, rotate slightly. In that case, you simply rotate it back into the timing position.

However, to do that, you would have to remove the timing belt from the crankshaft pulley again, because the fixed ESP wheel blocks the entire belt drive. And the crankshaft pulley is not rotatable relative to the crankshaft.

If it twists more than 5mm (measured on the OT indicator), the belt is installed incorrectly between the ESP and the KW.

Okay, this is getting interesting. Where's the OT indicator?

So, if I understand correctly, when installing the belt, you must align the exact number of teeth between the crankshaft (KW) and the ESP pulley, because the crankshaft pulley is not freely rotatable on the crankshaft, and therefore the crankshaft position relative to the ESP position cannot be adjusted once the belt is installed.

Regards,
Holger.

The indicator on the tachometer is, to put it mildly, borderline; what's meant is the marking on the flywheel.

The crankshaft is quite "gentle" when the belt is removed. Accordingly, during tensioning operations (which sometimes doesn't work right away if it's tightened too much or the locking nut slips ), the crankshaft may sometimes be slightly twisted. When adjusting to Top Dead Center (TDC), the crankshaft must not "rotate backwards" if the belt is properly installed (and tensioned), otherwise the number of teeth between the crankshaft and the ESP (Electronic Stability Program) will not match.}