Even Tooth Wear: Causes & Treatment

Hello everyone!

I removed a faulty starter motor from a T4 van with an AAB engine. This starter motor had chewed up the ring gear on two opposite sides.

The gear ring is damaged from approximately 1:30 AM to 4:30 AM and from 7:30 AM to 10:30 AM.

Ich hab mal gehöhrt, daß ein Motor beim abstellen immer in zwei Stellungen stehen bleibt. Stimmt das? WSure, why not?

That would explain the strange pattern of destruction.

Who can help me with this?

Goodbye, Tom.

constrictor wrote:

I once heard that a motor always remains in two positions when being turned off. Is that true? If so, why?

Hi Tom,

Simply put: In a 4-cylinder engine (except at top dead center), there's always one cylinder in the compression stroke and one in the power stroke simultaneously. The compression pressure pushes the engine away from top dead center as much as possible, until the stronger compression in another cylinder "blocks" it.

Therefore, the motor usually stops approximately halfway between top dead center (TDC) and bottom dead center (BDC).
(actually nonsense, because the OT of one cylinder is the UT of another cylinder ).

Hello Ulf.

Thank you for your quick and accurate response. If you think about it long enough, it makes sense.

Is there something similar for 5-cylinder engines?

Best regards, Tom.

Is the AAB engine the 5-cylinder engine without a turbocharger, with a 2.5-liter displacement?

Hi,


Without a turbo, that's correct.
One could also say that it's a 1.9-liter engine with a 5-cylinder configuration, where the bore and stroke are identical.
The 2.5-liter engine has a slightly larger bore.

The 2.4-liter engine was/is used in the T4.
And with a different engine code, it was also available in the Audi 100, allowing you to have great races with the Mercedes 200D models...

That's correct. The AAB engine is the 2.4-liter diesel with 5 cylinders and no turbocharger. However, Ulf was referring to a 4-cylinder engine (such as the ABL engine). That's why I asked about the 5-cylinder engine.

Best regards, Tom.