The Mazda MZR Super sport engine in my +4 has started making the dreaded and well documented rattle on start up. It would appear to be the well known issue in the Mazda world, failure of the what is commonly known as the VVT Solenoid Valve that controls oil to the VVT pulley on the inlet camshaft as i understand it. Failure of the Solenoid can apparently ultimately lead to timing chain failure and destructive contact between valves and pistons. A well known Mazda MX5 specialist in the North East tells me that this is possible but unlikely.
The parts to rectify include a timing chain , guides, new friction washers for the crankshaft pulley and camshaft VVT pulley and solenoid valve and come in at under £400 plus labour. Could be a cheap fix compared with a damaged engine,
There's quite a bit on the internet regarding the subject (Mazda VVT Problems) and in US Mazda has been involved in court cases due to this issue. I think i'll have it looked at in the near future. My engine has done 20k and had regular oil changes (max every 3k). Thought i had it cracked going back to a chain rather than a belt!
So i you have a timing chain like rattle on start up after being stood for a while it possibly due to loss of oil pressure in the VVT assembly.
