Defective hydraulic shock absorbers?

Hi,

since yesterday, my engine (AFN in T3 syncro, approx. 200,000 km) has been making a really awful noise.

I have recorded this noise today, and you can find it in a zip file with an mp3 file under the following download link:

/download.php?id=2026

It occurred after approximately 80 km on the highway, with the engine running at full load for a short period. The oil level was at the minimum, but there were no noticeable issues during the drive. The oil temperature reached a maximum of 115°C, and the oil pressure was normal.

I then drove the same distance back, after filling up the oil and driving much more slowly. Even today, after starting the engine, it became slightly quieter after a few seconds, but it is still extremely loud.

The knocking occurs exactly once every 2 engine revolutions (the exact idle speed of 861 1/min can be calculated from the sound file).

There are no errors in the memory, and all other data in the MSTG are plausible. The maximum deviation of the idle speed control is 0.82.

It also rattles at slightly higher RPMs, and it rattles even when operating under load.
Even when individual ESDs are removed, the rattling remains, although it does change slightly in sound.
My impression is that the noise comes from the valve mechanism, but that could also be wishful thinking.

My suspicion is that a hydro has given up.
Would you agree with my assessment, or have I perhaps overlooked something important?
I have to drive 600km next weekend, should I definitely get this checked beforehand, or can I drive like this?

Thank you and best regards,
dieter

Sounds suspicious, like a warehouse damage. It wouldn't be unusual in the T.

I had been experiencing a lot of pressure in the hydraulics for a while, which eventually went away after several longer trips. However, these were new hydraulics.

In your case, I can't say for sure, although I can hear it, I can't pinpoint the source. I would first listen with a stethoscope or screwdriver, and if it turns out to be the hydraulics, I would remove the valve cover.

It's likely nothing serious, but I would still want to get it checked out.

Hello,

So, I would immediately tackle the VD issue – it's quick, costs nothing, and might provide certainty.
With an additive/cleaner and oil change, I have also been able to eliminate the "hy-clacking" sound.

Does a bearing damage not particularly manifest itself as combustion on the worn connecting rod bearing, and then disappear without the injection of the nozzle – can it therefore be "fixed" by opening the fuel line?

Best regards,
derteileklaus

Hi,

thanks for the answers.

I think the first prize goes to Mulle, and I'd like to have the consolation prize.

I removed the cap this afternoon, and all the hydros are moving smoothly. I didn't get the impression that it was coming from above when I listened.

Then the engine probably needs to be checked.

Best regards,
Dieter

Congratulations to Mullemaus,
Caressing the sad Dieter-Armerschwarzerkater!
derteileklaus

Come on guys. Congratulations and prizes aren't necessary. It's a shame that it's probably a more serious problem. However, the problem isn't entirely uncommon with the T3, which is why I suspect that. An additional oil cooler and checking the vacuum/oil pump is almost always necessary for these modifications. Nevertheless, I wish you all the best and hope there are no further problems.

Hi,

I have the oil temperature and pressure. However, I don't have the radiator temperature because I usually don't kick it over and it always gets good oil. The temperature never really goes above 110°C.

The oil pressure and temperature were normal.

Anyway, I'm taking it to the workshop next weekend, then I'll see.
The annoying thing for me as a city dweller without a workshop is always the logistics.

Regards,
dieter

dieter hat folgendes geschrieben:

.... Oil pressure and temperature were normal. ...

Therefore, I doubt a bearing failure a little.
Even if a bearing failure doesn't make as much noise as this one, the oil temperatures are running very high.

A third possibility for this noise has not been mentioned at all: A faulty valve.

I would suggest removing the nozzles and, if one appears to be particularly wet, then you can almost certainly skip the cleaning process. However, I would still have it cleaned and observe the opening pressure. If it is significantly too low, the engine will also make a terrible noise.

This should be noticeable in the LR control system. It should indicate a problem with the cylinder.

If the nozzle is so leaky that it constantly "leaks", it can even make a hammering noise during operation. While this is rare, it can happen.

If that's not the problem, then the only remaining possibility is bearing damage. This would be the first time I've seen no unusual readings in the oil pressure and oil temperature.

However, my chances of finding another problem besides bearing damage are rather slim.

What happens if you have a noise caused by a faulty nozzle (opening pressure too low) and then go back to the default settings in MWB4, which adjusts the spray start time roughly between early and late? Shouldn't the knocking sound also change in this case?

If the knocking is caused by a bearing issue, shouldn't it be relatively independent of the spray start time in idle?

Could this be a possible way to find out?

Malte1408 hat folgendes geschrieben:

So, what happens if you have a noise like that caused by a faulty nozzle (opening pressure much too low) and then go back to the default settings in the MWB4, which roughly adjusts the start of the spray? Wouldn't that also change the hammering sound in that case?

That's right, but the faulty nozzle no longer responds to that. You're just creating additional hammering through the three intact nozzles.

Zitat:

If it's caused by a bearing failure, shouldn't the hammering be relatively independent of the spray start in the idle?

Exactly the same applies to a leaking nozzle.

Zitat:

Could that be a way to find out?

Unfortunately, no.

Let's assume that the faulty nozzle opens too early (or not at all properly) due to a broken spring, then no matter what you set the pump to, the nozzle will always uncontrollably inject diesel into the combustion chamber. Similarly, the uncontrolled ignition of this cylinder is also a problem.

I've heard a CR motor making a noise for quite a few days. The noise was just as awful. However, there was also a leaking injector.

The "DIY testing method" here was quite brutal. When the ignition was disabled during operation, the noise disappeared. If there was a bearing failure, it would remain.

dieter hat folgendes geschrieben:

Hi, It also rattles at slightly higher RPMs, and it rattles even under load. Even when individual ESDs are removed, the rattling remains, although the sound changes slightly. Thanks and best regards, dieter

No injection at full throttle - also when disconnecting the lines!
The noise remains!
Therefore, it cannot be the injector - or am I wrong?
derteileklaus

teileklaus hat folgendes geschrieben:

... No injection when idling - also loosen the lines! The noise remains! Therefore, it cannot be the injector - am I wrong?

No, you're not mistaken.
However, if the nozzle drips because it doesn't (properly) seal, then it will continue to rattle for a while during operation. This will continue until there is no more diesel in the lines to the nozzle. Even if it's only a few drops, the lines will take forever to drain.
This (admittedly rare) defect has not occurred to me on a VP37, but it has on a WK engine.

Now, when turning on the LL, the clicking sound should disappear!
Can a bearing make clicking noises, are they similar?
The nozzle could be moved to a different cylinder for comparison to see if the noise travels with it.
Best regards, derteileklaus

teileklaus hat folgendes geschrieben:

Okay, but when turning on the fuel line for LL, shouldn't the clacking noise disappear!

Only if 100% of the diesel actually from the fuel line is kept away from the nozzle. With a VP37, completely disconnecting the line is very dangerous. I doubt Dieter completely disconnected the line.
The change in the noise is already mentioned in the starting thread. This could be due to two reasons. The load on the supposedly defective bearings is lower, and the noise changes. Or, the amount of diesel flowing uncontrollably is lower, and the noise changes.

Zitat:

Can bearings make clacking noises? Are they similar?

Unfortunately, there are no "standard noises", so it is very difficult to distinguish them. Especially if you are not "live" in front of the engine.

Zitat:

The nozzle could be moved to a different cylinder for comparison to see if the noise travels with it.

As long as it's not the NHG... Yes. But you have to listen with a stethoscope. Then you will definitely hear the origin of the noise (head or block).

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