- My model of MX-5 is: NC
- I’m based near: Leeds
- I’m looking for technical help or recommendations on: Engine smoking/breather systems
My 2006 NC has just failed the MOT on excessive blue (oil) smoke when engine is held at 2500 rpm for 2 minutes which is a part of the MOT test. I have simulated this in my drive and after a couple of minutes is starts to blow blue smoke out of the exhaust. The car has covered just over 90000 miles. I have carried out a compression test with the following results: #1: 180psi, #2 179psi, #3 181psi & #4 179 so all seems good there. I know that one other possible cause of excessive smoke could be worn valve guides or faulty valve stem seals but having completely rebuilt three NA engines in the past, all of which had in excess of 100,000 miles on them and found very little in the way of bore wear, stem seals or valve guide wear I don’t think there is a problen with those. When I take the oil filler cap off and put my hand over the opening there is a definite positive pressure there. This is my first NC model and I am not familiar with the engine breather system. Has anyone else had this problem or can advise me of any blockages/issues with the breather system or other issues that could cause this? The car drives well and has shown no signs of smoke under normal driving conditions, hard acceleration etc. I am reluctant to take the head off unless I have ruled out all other possibilities. Regards, Les
The breather valve may be blocked, which is quite cheap to replace; a diagram is here on where to find it. PCV Valve / Breather Valve - MX5 MK3 / NC (06-15) | MazSpec NC PCV valve replacement. - #2 by TerryO
Many thanks Raymond, I did wonder about that having read one of two posts about the same problem. I just ordered one. I remember there was one on the intake side of the cam cover on the Eunos, much easier to get to. I replaced it as a matter of course when I did the full rebuild on the Eunos engine.