Hi, might seem like a simple question but 1. where is the PCV and 2. can you check it yourself to see if its blocked/causing probs?
The PCV valve is in the short rubber tube which links the cam cover to the inlet manifold. The PCV is at the cam cover end of the tube and is just a push fit into the cam cover.
You can give it a basic check, in that you ought to be able to blow through it from the engine side, but not from the manifold side (clean it up first! [+o(] )
It’s not a 100% reliable test, though, as the operation of the valve’s a bit more subtle than that: It should close to prevent air flowing from the manifold into the engine, and it should allow air to flow in the opposite direction, but only if the manifold vacuum isn’t too strong. If the manifold is trying to suck too hard (such as at idle) the valve should close up in that direction too.
If it checks out OK but you’re still suspicious of it, I seem to recall it’s cheap to replace.
Cheers Martin, will have a look tonite if nowt obvious will get it replaced.
What symptoms are you having that made you ask the question?
Increased oil useage with no apparent reason why. Its not coming out the back end and there are no leaks. I’ve been told the SC will cause it to use more oil and its using what other SC MX’s are but just wanted to cover all bases as it was suggested in a post that a blocked PCV will cause more oil use apparently.
G’day Hedge
How much oil is the engine using? Mine uses no more with the SC fitted than it did before, maybe 1/3 litre between changes
Hi Geoff,
She’s using about a litre every 1000 to 1500 miles depending how heavy my rt foot is 
I jury rigged a clear fuel filter between the PCV and inlet manifold, to see just how much oil was getting through, in a dying engine. Quite a lot was, but not in the quantities I was having to top off with. Smoke at start-up was a big give away. Pulled the head off the engine, after it was swapped out (180k kms, 1996 1.8) and found the rings had gone.
Hi, I have no smoke at on start up, no smoke when accelerating hard and no oily soot on the tail pipe. No loss of power, no increased temps, no leaks, nothing.
Mine is consuming oil at the same rate (at 300k kms). I’m pretty sure it’s the rings. It’s not a large sample size, but noticing that we all have 1.8 engines, I wonder if this may be common on BP’s but not B6’s.
Compression test was:
Cylinder: 1 2 3 4
Dry: 200 195 180 200
Wet: 220 220 210 X
Which ain’t too bad, but cylinder 3’s down a bit compared to the others. I have a low-mileage used engine in my garage now, waiting for me to work up the determination to fit it…
Certainly a comment I have heard from a well known MX5 specialist is that there are a lot more problems with the 1.8 than 1.6.