Burning Oil

[Collaudatore]

MK1 MX5 ownership not feeling so sweet now.
Noticed a little puff of something as I was driving yesterday and checked the oil today - almost at minimum. There doesn't appear to be anything leaking, nor was there anything leaking when it was almost full when I bought it.

Again....

What could the problem be? Anything else I could check to help diagnose?

[pbirkett]

CAS O-ring? Common fault, mine was leaking when i got mine. Cheap to repair.

[Gizmo!]

pbirkett said:

CAS O-ring? Common fault, mine was leaking when i got mine. Cheap to repair.

Mine too. I thought I could smell something when it was warming up, turned out it was split. Very easy fix.

[Collaudatore]

Cheers guys. I'll go get my hammers and let you know how it goes.

[5paul5]

Think i have the same problem with mine, it smokes a bit on the overrun from the exhaust. Could it be the CAS O ring and where do i find it ?

[WarrenG]

I babied out on the last week of snow driving, and noticed a nice plume of blue on startup, from stone-cold after a week's idle.

It doesn't do it on a startup on a morning cold, following a drive the previous day, but always after a few days not driven. is that related to the CAS O-ring (Crank Angle Sensor?) or is it just ring-pump on a cold, worn engine?

[DennisTheMenace]

5paul5 said:

Think i have the same problem with mine, it smokes a bit on the overrun from the exhaust. Could it be the CAS O ring and where do i find it ?

I would say its more likely to be valve stem seals or the rings on no.4 piston letting oil past .

[MX-5 Lazza]

CAS O-ring failing causes an oil-leak that can trickle down onto the exhaust manifold so give a little under-bonnet smoke but usually just causes oil-drips on your driveway. It won't have anything to do with smoke from the exhaust.

Edited by MX-5 Lazza on Friday 15th January 08:37

[dylan0451]

DennisTheMenace said:

the rings on no.4 piston letting oil past .

sorry, quick hijack...

is it that common for no.4 to start burning oil?

i was looking at the coolant re route kit FM do as part of my base upgrades before i consider more power, but wasn't sure it it was worthwhile

[bluetone]

MX-5 Lazza said:

CAS O-ring failing causes an oil-leak that can trickle down onto the exhaust manifold so give a little under-bonnet smoke but usually just causes oil-drips on your driveway. It won't have anything to do with smoke from the exhaust.

^^^ What Lazza said.

Don't tend to 'hear' (on fora) of many smoky exhausts tbh..