6 replies to this topic

[lewis9393]

City 998:
1992:
When in fourth gear doing above 3000+ RPM the car runs fine, when the pedal is let go of completely (not when just letting off) it also appears to be no problems, the problem occurs when the pedal is pressed again and a plume of smoke comes out the back, its a quite big cloud, not a dark cloud and smells like oil/fuel... its hard to say. I took it to southam and they said definitivly that it was the piston oil seals, they changed these (free of charge due to buying the engine from them) but the problem is the same and the engine is also overheating quite quickly.

I hope someone can shed some light on the situation



Stage 1 kit

[Dan]

Piston oil seals? I presume they mean the oil ring. Sounds like a cracked compression ring to me to be honest. But if they've changed the rings and is persists it could be that the bore has been scored by the broken ring, although they should have spotted that in the rebuild. Is the engine new? Did you run it in properly? Did you run it in properly with the new rings?

[1977 Loud_Mini]

My old 998cc engine did this and so does my 1275 i have in there now. It's just when they are getting a bit worn out (piston rings). Could also possibly be the valve guide seals.

Evan.

[Stevie W]

I once had a series 3 Allegro that did exactly what your Mini is doing....it turned out to be worn exhaust valve guides and knackered valve stem oil seals.

Steve.

[Boycie]

What you've described is classic symptoms of worn valve guides. In your case, it sounds like the engine has been rebuilt relatively recently? I think it possibly has a valve guide/ valve stem or valve stem oil seal fault (probably what they changed before).
Another cause for smoke is indeed piston or ring problems, but these tend to manifest themselves by smoking under acceleration.

I'm not sure what the overheating issue is, but I would check you have good flow through your radiator, the fan is on the correct way round and your brakes aren't binding.

[Dan]

but these tend to manifest themselves by smoking under acceleration

Yes under load. That's what I thought was meant when he said it happens when he hits the throttle again.

Was it overheating before it went back for the repair?

[bmcecosse]

Sounds to me like piston rings/pistons/bores gone- sure their earlier 'repair' wasn't just valve stem seals - which are cheap and easy to do - and generally a complete waste of time............. depends what you thought had been done to the engine before you bought it - but take it back to them anyway and tell them to FIX IT!!

Edited by bmcecosse, 30 May 2011 - 07:55 PM.