Hi
I am in need of some advice again please. My Mk 1 1.8 is laid up for the winter but i am doing some minor works. Moving the car today for the first time after a few weeks of inactivity i noticed smoke coming from under the bonett. Seemed to be coming from under heat sheild of exhaust manifold. After wrestling all bar one bolt off the shield i exposed the manifold. There is a pipe which seems to screw into one the branches of the manifold - what is that - what does it do - the smoke seems to be coming from that and it looks a bit oily?. Also noticed oil dripping on bulkhead end of rocker cover?. Do i have a problem?
Any advice welcome.
Thanks in anticipation
Seems likely you are burning oil off on the exhaust manifold. I had this problem, and mine had been laid up for a few weeks. Check your cam cover gasket, especially around the CAS seal too, tell tail sign as you say oil around the rear of the cover. Also pop the plug leads out and look down the well holes, mine had oil down there too.
The pipe you mention, mine needed nipping up with a spanner it was a little loose as I noticed smoke from there but I reckon it was only the oil as said burning off as it had stood for a while.
If it’s as I mention do both the cam cover gasket and CAS seal as well whilst there. Use genuine Mazda gaskets.
Hi, thanks for your reply. What is the CAS. How easy is it to replace gaskets for both?
Good advice from Mick. CAS is Cam Angle Sensor. There is an o ring that seals it in which commonly leaks with age. These are not that difficult to fix if you know how 
The rocker cover gasket is not difficult either, but a good quality one is necessary and a little RTV in a couple of places to ensure a good seal
Eddy
The cam cover gasket
http://www.mx5oc.co.uk/forum/yaf_postst158_How-to----Change-the-cam-Cover-Gasket.aspx
The CAS oil seal
http://www.mx5oc.co.uk/forum/yaf_postst214_CAS-O-Ring-change–NA–MK1.aspx
Easier to do the CAS seal when you have the cam cover off. You still need to mark the position of it before removal (the CAS)
Easy enough job, just remember to put a blob of silicone at the points mentioned in the"How to" when fixing the new gasket just a small amount will do it. And if you don’t have a torque wrench for tightening the bolts down, 2 light finger pressure on your wrench should do it for the final tighten down in sequence.
That guide shows the 1.6 engine, your CAS for the 1.8 will be exhaust side rear of the cam cover/engine.