Crankshaft Vibration Dampers

Hi there,
I have a technical question about vibration dampers for Volkswagen diesel engines.
This specifically refers to a very old engine generation: inline 5- and 6-cylinder engines with swirl chambers and distributor injection pumps from the 1980s.
Back then, Audi had 5-cylinder engines (e.g., engine codes CN, DE, NC), and the Volvo 240 had 5-cylinder engines (D20, only in Italy and Finland). The LT models featured 6-cylinder engines (e.g., engine codes DW, 1G, ACL), as did some Volvos (D24).

The two engine types are very similar from a technical standpoint; they actually only differ in the number of cylinders.

Both have a very similar vibration damper on the crankshaft, often referred to as a pulley (crankshaft). However, the vibration dampers are not identical in construction, even though they have the same external dimensions. For example, this is the case with Volvo D20 and D24 engines; the dampers are the same size/weight but are not identical.

Does anyone know if the vibration dampers are specifically balanced? I mean, not to a "zero imbalance" state, but especially in the case of the 5-cylinder engine, with a precisely defined amount of imbalance?
If that were the case: Could a vibration damper from a 6-cylinder engine be modified to work on a 5-cylinder engine? It fits mechanically, but I'm more concerned about balancing the engine vibrations.
The reason is that spare parts for the 5-cylinder engine are no longer available, while they are still obtainable for the 6-cylinder engine.

Hi there,


The 5-cylinder and 6-cylinder engines are not interchangeable with each other, nor are the 5-cylinder engines if they have different sized clutch discs.
The vibration damper (pulley) at the front of the crankshaft is balanced together with the crankshaft, just like the flywheel.
The crankshaft, connecting rod, and balancing weights form a single unit in the overall mass balance.
"There have been people who installed the exhaust manifolds from the 5-cylinder gasoline engines during modifications, as they were considered 'lighter'."
Unfortunately, it almost always resulted in catastrophic failure (due to enormous vibrations, hairline cracks in the transmission housing, broken engine mounts, or even a broken crankshaft).
Even if the bore/stroke ratio is correct and the 2.0 kW output is the same, the connecting rods and pistons in a diesel engine are heavier, which results in different inertia and wear characteristics.

In the past, Audi used what were called "master weights" for balancing the 5-cylinder crankshafts.
These were screwed into various locations on the kilowatt-hour meter housings, allowing the different masses of the various ranking levels to be "filtered out" and thus counterbalanced.
That's also why there are mounting holes in the cheeks of the 5-cylinder crankshafts.

Specific answer: It's best to use the exact component that is appropriate for the application.

Regards,
Mpire

Hi there,

Or you could find an engine rebuilder who can rebalance the entire assembly for you. What if you can't even get parts for a 5-cylinder engine anymore?

Best regards.
Adrian.

Thank you for the information.
Were the specific imbalances determined only once for each engine/flywheel combination during the initial design phase?
In mass production, not every crankshaft is balanced in the assembled engine.
Flywheels and vibration damping pulley discs can be easily replaced individually, which means they must have a specific balancing requirement for each component series.
I suspect that this data is not publicly available, which means you can't simply ask Audi or VW how to balance the shock absorbers.

Can the weight be determined based on an existing pattern? If so, who can do this? What kind of testing equipment is needed for that?

If you're interested, check out the videos by Philipp Kaess at BP Motorentechnik.

Björn Pieper is lifting heavy weights and explaining a lot, which I find extremely interesting.

https://www.youtube.com/watch?v=8yzIdQadvns and the following.

The vibration dampers/crankshaft pulleys are at least engine-type specific for 4-cylinder engines and were (are) available as individual replacement parts (and it worked).
I'm sorry, but I can't translate "hgf" because it doesn't appear to be a word or phrase in German. It might be an abbreviation or code that requires more context to understand.
Herbert.

Jens 16syncro wrote:

Thank you for the information. Were the specific imbalances determined only once for each engine/flywheel combination during the initial design phase? In mass production, not every crankshaft is balanced in the assembled engine. Flywheels and vibration damping pulley discs can be easily replaced individually, which means they must have a specific balancing requirement for each component series.

Of course, components with the same designation code are interchangeable within engines, but not between engines with different "setups" (different flywheels, larger/smaller clutches, different connecting rods/pistons - weight).
The serial part with the same number is always considered "identical" to another serial part with the same number, within the limits of manufacturing tolerances.

"069105251D would be the part number for all 2.0 D/TD swirl chamber diesel engines in passenger cars from 1978 to 1991."
Erhältlich bei Audi für 246€ incl. Mwst

Regards,
Mpire

The pulley for the 2.0 TD engine (5-cylinder) was available as part of the industrial engine range until 2007.
It costs just €196.95 at the Audi shop.
https://trshop.audi.de
I would like to install the pulley on the 2.5 TDI because pulleys for ribbed belts are only available for that engine.
I might do a comparison of the two discs sometime, to see how they differ in terms of overall weight and balance.