2002 auto Hilux - unusual clacking sound when cold

[poitr]

My 2002 petrol auto Hilux ute (an RZN 149R model) has developed an unusual clacking sound which my Toyota dealer and a local mechanic are unable to explain. The ute has done 200,000 km of light work, has been regularly serviced and is in overall good nick. The noise has just started as we have moved into the cooler weather. After nights where the temperature has dropped below 10 degrees, when starting the engine and then shifting the transmission into drive, there is a clacking sound which goes for about 5 to 10 seconds, before disappearing. The sound only starts after drive is engaged, and it goes for the 5 - 10 seconds whether the ute is stationary or moving. It sounds a bit like a belt whacking on something metallic but all the belts are tight and OK. The engine and transmission oil levels are both fine. The ute has been up on a hoist and checked thoroughly twice, but there is nothing loose or out of the ordinary to see in the engine bay or underneath.  The problem is  that I leave the ute with mechanics overnight but the noise runs for such a short time that its so far been impossible for any of them to diagnose the issue. I've downloaded a phone recording of the noise which I hope comes through OK  (its 37 mgb, so please give it time to load).  Any help or suggestions will be very much appreciated.

Thanks,   Poitr

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Edited June 11, 2017 by poitr

[campbeam]

It could possibly be somewhat similar to the dreaded VVTi rattle [applicable to 2GR-FE engine} that is oil pressure related on startup. I would be considering further checks of the oil pressure within the transmission and torque convertor.

[poitr]

Thanks Ashley, much appreciated.

Poitr

[campbeam]

Just remember that this is sheer speculation on my part. My initial thought/suspect was low transmission fluid level but as you have stated engine and transmission fluid levels are fine.  I would be inclined to also search for any Toyota Service Bulletins relating to your vehicle especially the transmission and/or torque convertor.

Something else to consider is when the transmission was last serviced to either flush or replace the transmission fluid and whether the transmission filter is due/overdue to be replaced.

[poitr]

Thanks again Ashley. Its the best that anyone's come up with so far

Poitr

[trentmeyer23]

The sound is like a lifter knock, but the symptoms and conditions say otherwise.

[poitr]

Trent,

The old girl has started making the noise now when the engine is turned on, before putting into drive, so you might be on the money  with lifter. We will try something like liquid moly and see how it goes. Thanks for the comment.