Clutch engaged or not on starting?

[Jode]

I began doing vehicle repair at the same time as I learned to drive, as an older mate just back from 'Nam was a keen VW driver and willing to help me learn. He taught me to always disengage the clutch when starting in order to reduce the inertia that the starter motor must overcome when kicking in.

I read a recent post on landrovernet, where it was stated that starting with the clutch disengaged may lead to crank thrust washer failure, as the crank is pushed forward agains the thrust washers by the clutch, and the washers being dry will experience increased wear.

This doesn't make sense to me, as I wouldn't have thought that the clutch fork assembly would be able to transmit axial forces via the release bearing to the cranckshaft; however I'm no expert and may have misunderstood something.

I'd be keen to read other's take on this.

[JDNSW]

Both concerns are valid in theory, but neither holds much water in practice.

Starting with the clutch disengaged may have some validity in a very cold climate where the drag of the gearbox is significant, and the battery may be marginal, but in normal Australian conditions, it won't make a significant difference. Inertia of the gearbox and clutch driven plate will always be negligible compared to that of the flywheel and crankshaft, especially in a diesel. Note, however, that starting with the clutch disengaged is generally considered good practice from a safety point of view, and many current cars enforce this with an inhibitor switch on the clutch.

Certainly, starting with the clutch disengaged will put a load on the crankshaft thrust bearing (usually a thrust washer), but this will not normally be dry unless the vehicle has been standing for a long time, and most diesels start after perhaps half a turn, anyway.

John

[JDNSW]

Both concerns are valid in theory, but neither holds much water in practice.

Starting with the clutch disengaged may have some validity in a very cold climate where the drag of the gearbox is significant, and the battery may be marginal, but in normal Australian conditions, it won't make a significant difference. Inertia of the gearbox and clutch driven plate will always be negligible compared to that of the flywheel and crankshaft, especially in a diesel. Note, however, that starting with the clutch disengaged is generally considered good practice from a safety point of view, and many current cars enforce this with an inhibitor switch on the clutch.

Certainly, starting with the clutch disengaged will put a load on the crankshaft thrust bearing (usually a thrust washer), but this will not normally be dry unless the vehicle has been standing for a long time, and most diesels start after perhaps half a turn, anyway. And the crankshaft bearings, which handle much higher loads, are also dry if the thrust bearing is.

John