MX5Ireland

Ok I'm off throttle, slowing down. When i put my foot back on the gas she whips out big cloud of blue smoke and I'm very sure it's oil.

If I'm slowing down and knock her into neutral then get back into gear then accel off there's NO smoke.

I would guess its the valve stem oil seals. Anyone else had this sort of problem before?

heh just noticed your sig

So, its blowing smoke after some negative pressure in the cylinder... rings or valve guide seals? Prob the seals.

I have a compression tester you can use - although haven't fitted it to the MX5 yet (with its deep sparkplug wells).

If you are sitting at idle for 10 mins and take off, is there a puff of smoke ? That would also point to stem seals.

One thing you could try is the PCV valve on the cam cover - pop in a known good one (ie. not mine ) and see if that was the cause...

The other thing it could be is the cam-cover's oil vapour thing into the intake tract (ie the other end of the PCV system). My turbo was sucking oil out of the cam-cover when coming off throttle, building up oil in the intercooler, and then 30 seconds later releasing it into the intake manifold - results were spectacular double-plumes of smoke out the back of the car. Nice smoke-screen, especially when the cloud would actually hang there at street level for about 30 seconds. Making it happen at packed bus-stops was particularly enjoyable.

Anyway, I solved that by fitting a catch-can and plumbing the cam-cover pipe into it

I've tried disconnecting the passenger side cam cover hose it made no difference.

I think I could have a bad PCV, since at idle at traffic light i don't get smoke when i take off but I'll confirm it.

on your boost gauge, is it -19(ish) at idle?
When you engine brake this should go a good bit higher, then oil is sucked past the rings?

Hmm I'll have to check that at home. I dont' ahve a boost gauge in the car.

I'm going to do a leakage test anyway, but me mate broke my meter so he's replacing it this week.

Fingers crossed rings are ok. Last time I saw a turbo car with blown rings it smoked ALL the time.

Drove around with the two lines on the cam cover removed... No luck .

Still.. off throttle for 3 secs and back on throttle it shoots out blue smoke.

I'd take Frank up on his offer..

Just replaced the Valve stem seals. No luck I have a handy remover that lets you do it with the head still on if any member needs it.


Steve the car was pulling 20in vac at idle so i don't think i have any leaks.

I have a feeling it is the PCV, I knew the crankcase was leaking before and it's only happening since i fixed it.

It really does sound like what Ivan went through with his turbo.

Whats the latest?
Did you try relocating your catch can pipes to the other side of the cam cover?

No updates. Shes been sitting still all weekend due to a burst heater hose.

I'm beginging to suspect the rings. New engine is in order me thinks.