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How many of you M42 owners hear loud ticking sound, especially on a cold start? My guesses are as follow:
- failing chain tensioner
- timing chain 
- bearing bush (hope not!)
The sound increases with rpm's increas. Any gueses?
Thanks

I think chain tensioner is the most common of those.  A plug wire that is shorting out will make a ticking noise also, as can accessory pulleys or tensioners on the belt.  But, it goes away after the car has warmed up??  Try a thicker oil.

Hi, thanks for your response, i don't think it's hydraulic valve lifter so oil change to thicker won't help. It is quite noisy when the engine's cold but i can still hear it after warming up. I bet on pulleys or tensioner as you said.
How can shorting plug wire make such a ticking noise? That's odd to me  ::)   

As teh spark arcs from teh wire to where ever it is grounding, it will make click or snap nosie as it jumps.

The ticking sound definitely comes from the front of the engine (where the water pump is locted and all the pulleys) and i only hope that engine diagnosis will tell me what is it for sure.
Thanks again

M42's have self adjusting valves so that's probably not the problem, although any oil buildup on the valve train may cause problems with the adjustment, causing them to tick.  This is a known problem with the M20 but you can adjust them yourself, so its easier to deal with. Injectors are also known ot tick excessively and are often the noise you hear.  The association of the sound level with the engine warmth suggests the valves to me since the warmer it gets, the more the valve train will expand and close any gaps that aren't supposed to be there.  The lash settings on the valve train are pretty small, so expansion due to heat will definitely cause the noise to quite down a bit.

OK i have an answer! I was changing the gasket (cylinder head cover) so i looked at cam shafts and they seem great. Anyway the sound still annoyed me - so mechanic went under the car and i pushed the gas pedal. It appeared to be a little hole in a pipe just next to exhaust manifold that makes that ticking sound during acceleration  ;) Welding is coming next but i'm all better now knowing it wasn't the engine's fault.

cool, good to hear that it's just a minor thing.. :)

glad to hear its just ur exhaust, from the explanation sounded to me like it would've been the shorting plug! never happened to me. hope its that tell us if it comes back!!