Lifter Failure? Diagnose and Repair.

Hi,

"Since yesterday, my engine (AFN in a T3 Syncro with approximately 200,000 km) has been making a terrible rattling noise."

I recorded it today, and you can find a zip file containing an mp3 file under the download link.

/download.php?id=2026

It occurred after approximately 80 km of highway driving, during which there was a brief period of full acceleration. The oil level was at the minimum mark, but there were no noticeable issues during the drive. The maximum oil temperature was 115°C, and the oil pressure was normal.
After refilling the oil and driving back the same distance, it was much quieter, but still noticeably loud. Even today, after a cold start, it was slightly quieter after a few seconds, but it's still extremely loud.

The knocking occurs exactly once every two engine revolutions (the exact speed of 861 RPM can be calculated from the sound file).

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

It rattles even at slightly higher speeds, and it also rattles during thrust.
Even when unscrewing the ESDs one by one, the rattling sound remains, although it may change slightly in tone.
My impression is that the noise is coming from the valve mechanism, but that might just be wishful thinking.

My current suspicion is that a hydraulic component has failed.
Would you agree with my assessment, or have I perhaps overlooked something important?
I have to drive 600 km next weekend. Should I definitely get it fixed beforehand, or can I drive it like that?

Thank you very much and best regards,
dieter

Sounds suspiciously like storage damage. That wouldn't be unusual in the T.

I once had a persistent ticking sound coming from the hydrofoils, which only disappeared completely after several longer trips. However, those were new hydrofoils.

In your case, I can't pinpoint the exact cause, as it sounds good, but it's difficult to locate the problem on the machine. I would first use a stethoscope or screwdriver to listen closely, and if it's the hydraulics, I would remove the valve cover.

Probably nothing will happen, but something will still be done.

Hello,
Okay, I would immediately run a virus scan. It's quick, costs nothing, and might provide some certainty.
I've also gotten rid of the Hy-clack noise before by using an additive/cleaner and changing the oil.
If a bearing damage doesn't manifest significantly during combustion in the defective connecting rod bearing, and the issue disappears when the injector is disabled (i.e., by opening the fuel line), can it be "resolved" simply by opening the fuel line?
Best regards, derteileklaus.

Hi,

Thank you for the answers.

It seems Mulle is likely to win first prize, but I would like to receive the consolation prize.

This afternoon, I removed the cover, and all the hydraulic components seem to be in good condition with no play. When I listened, I didn't get the impression that the noise was coming from the top.

Then the engine will probably have to be removed.

Sad greetings,
dieter

Congratulations to Mullemaus.
Petting the Sad Dieter - a black cat!
derteileklaus

Hey guys. Congratulations, and no praise is needed. It's a shame that it seems to be a more significant issue. However, this problem isn't entirely uncommon with the T3, which is why I suspected something like this. An additional oil cooler and checking the vacuum/oil pump are almost always necessary with these modifications. Nevertheless, good luck and hopefully minimal further damage.

Hi,

I have the oil temperature and pressure readings. I don't have a coolant temperature sensor, but since I rarely push the engine hard and always use good quality oil, I think that's probably okay. The oil temperature never really goes above 110°C.

The oil pressure and temperature were normal.

Anyway, next weekend I'm taking it to the workshop, and then I'll see.
For me, as a city dweller without a workshop, the annoying part about things like that is always the logistics.

Greetings,
dieter

dieter wrote:

.... The oil pressure and temperature were normal. ...

Therefore, I'm a little skeptical about bearing damage.
Even if a bearing failure doesn't rattle as loudly as this one, the oil temperatures can quickly become extremely high.

A third possible cause for this noise, which hasn't been mentioned so far, is a faulty nozzle.

I would suggest removing the injectors and checking them. If one appears to be excessively wet, you might be able to skip the cleaning process. However, it's still a good idea to have them cleaned and observe the opening pressure. If the opening pressure is significantly too low, the engine will run very poorly.
However, this should be noticeable in the LR (Land Registry) records. The information should be incorrect for a cylinder.
If the nozzle is leaking to the point where it's constantly "dripping," it can even cause the engine to stall during acceleration. This is rare, but it can happen.

If that's not it either, then the only remaining possibility is bearing damage. That would be the first scenario for me without any abnormalities in the oil pressure and the oil temperature.
My hope for damage other than storage damage is, however, rather low.

What happens if a faulty nozzle (with a pressure that is far too low) makes such a noise, and then you go to the "basic setting" in MWB4? This setting roughly adjusts the injection start time, shifting it between "early" and "late." In this case, wouldn't the knocking sound also change in tone?

If it's caused by a problem with the carburetor, the knocking sound should be relatively independent of when the spraying starts in the idle mode.

Could this potentially be a way to figure something like that out?

Malte1408 wrote:

What happens if a faulty nozzle (with a much too low opening pressure) causes such a noise, and then you go to the basic setting in MWB4? In that case, the start of injection is roughly adjusted between early and late. Then, in this case, wouldn't the knocking also change in sound?

Yes, but the faulty nozzle no longer responds to that. You're just creating additional noise from the three working nozzles.

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If it's caused by a wear issue, the knocking sound should be relatively independent of when the spraying starts in idle.

Similarly, this can also happen with a nozzle that is leaking.

Quote:

Could this potentially be a way to figure something like that out?

Unfortunately, not.

Let's assume that the faulty injector opens too early (or doesn't close properly) due to a broken spring. In that case, no matter how you adjust the pump, the injector will always allow uncontrolled diesel to enter the combustion chamber. Consequently, the ignition in this cylinder will also be uncontrolled.

I heard something similar from a CR engine a few days ago. The noise was just as awful. In that case, it was "only" a leaky injector.
By the way, the "DIY troubleshooting method" was quite drastic here. Turning off the ignition while the engine was running eliminated the rattling sound. However, if it were a bearing problem, it would persist.

dieter wrote:

Hi, It rattles even at slightly higher speeds, and it also rattles during thrust. Even when unscrewing the ESDs one by one, the rattling sound remains, although it may change slightly in tone. Thank you very much and best regards, dieter

Do not inject fuel during overrun. Also, do not loosen the screws while the lines are under pressure!
Noise stays!
So, it can't be a nozzle, or am I wrong?
derteileklaus

teileklaus wrote:

... Do not inject fuel during overrun. Also, do not loosen the screws while the lines are under pressure! Noise stays! So, it can't be a nozzle, or am I wrong?

No, you're not wrong.
If the nozzle drips because it doesn't (fully) close, it will continue to make noise during operation. This will continue until there is no more diesel fuel in the lines leading to the nozzle. Even if it's just a few drops, it takes a very long time for the fuel to drain from the lines.
This (admittedly rare) defect has not yet occurred in a VP37 for me, but it has happened with a WK engine.

Okay, but when the water pressure is increased in LL, shouldn't the hammering noise disappear?
Can a warehouse make noises similar to the sound of nails?
The nozzle could be moved to a different cylinder for comparison to see if the noise travels along with it.
Best regards, derteileklaus.

teileklaus wrote:

Okay, but when you increase the flow rate at LL, shouldn't the hammering go away!

Only if 100% of the diesel fuel from the pressure line is actually kept away from the injector. However, completely disconnecting the line on a VP37 is very dangerous. I doubt that Dieter completely disconnected the line.
As mentioned in the original post, the sound has changed. This could be due to two reasons: either the load on the supposedly defective bearing is lower, which changes the sound, or the amount of diesel fuel passing through uncontrollably is less, also changing the sound.

Quote:

Can a warehouse make noises similar to the sound of nails?

Unfortunately, there are no "standard sounds," which makes it very difficult to distinguish between these noises, especially if you're not standing directly in front of the engine.

Quote:

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

If it's not the NHG... Yes. To determine that, you need to listen with a stethoscope. Then you'll be able to hear the origin of the sound (whether it's coming from the head or the block).

contributes nothing, please delete.