Recently I have fitted new water pump, cam belt kit and alternator. On starting it up, there is a ‘noise’ - not good at describing noises, so recorded short video (here: https://www.youtube.com/results?sp=EgIIAVAU&q=mx5+vvt)
Immediate guess was the timing was out, so took valve cover and belt cover off, but all was spot on. Put it back together and ran it a few minutes, when it began to sound like a bag of spanners.
Did a compression test (someone suggested a dropped valve) and have readings of 115/115/120/135 (1-4 respectively), so although low, probably not a dropped valve. Sounded normal when spinning over.
Any suggestions anyone?
TIA
Have you got the firing order right? 
Thanks for the reply safetymatch, but it’s a VVT with the 2 coil packs on the valve cover - I didn’t take the plug leads off the coil packs, so very difficult to get wrong due to lead lengths.
Take the front covers off and look for something loose in there.
Take the alternator belt off and try it again.
Sounds like something belt driven making that noise rather than an engine problem.
Water pumps usually squeak or squeal.
It’s a strange one.
I did try starting it after removing power steering, then with alternator/water pump belt off as well - still sounded the same.
This all started when the alternator belt went (it had been squealing on start up for a while). AA said water pump was seized, so got pump and belt kit, only to find it was the alternator that was seized! I suspect the original pump, so changed it anyway. Never trust the AA opinion!
Sounds like I’m going to be tearing it all down again next weekend … Still, I’ll be able to do a cambelt in couple of hours next time![]()
Thanks for all your help.
What’s the sound like? The link to your video isn’t working for me…
Cheers,
Alex