Piston rings?

[Godzilla]

When on start up in my 91 Digi she lets out white smoke, this goes after 5 mins or so. A few things that I have been told could be piston rings. 1....hard throttle white/blue smoke  2.... oil around one of the spark plugs.......  any ideas?  Also if it is piston rings is it a big job, are we talking monster money, could it be worth me getting a 2.0 8v engine from a MK3 GTI and using my 1.8 MK2 head...... I know this works well on the MK2 Valvers.

[DarnPB]

It could be piston rings, or if it is only white smoke, it could only be the head gasket. If you have a rings issue, then you may also get crank case compression. Check this out by running the engine, then remove the dipstick whilst still running and feel for excessive gasses coming from the dipstick tube. Also, if you had a rings problem, your emissions would be high.
If you only get smoke on initial start up, when the engine is cold, then I would go for valve guide seals.
Get a compression test done and this may tell you if rings could be at fault. But be aware that if the compressions are low, it could also indicate badly seating valves, which would not necessarily be the cause of your symptoms.

[russ-vdub]

just rebuild the lot, thats if you have another car to drive in the mean while ive just been banned for a month yesterday so my engine came out last night, rebuilding the bottom end (head was done 1 year ago) and then you'll know its pucker.

[wopdat]

It is natural to get some white smoke when the car is initially started... it is usually water but you can check this by puting your hand over the exhaust and checking your palm whether it is oil or water.

As for the blue smoke during hard revs could mean that the valve stem seals are worn. If they are badly worn then you will get a puff of blue smoke when you pull off from a stationary position (i.e. traffic lights).

I would firstly check the compression on each cylinder, this will tell you if your piston rings have gone but i think it is highly unlikely. I do think it may be your stem seals on the way out but then again it may not need immediate change as mine have been like that for over 6 months!!

If you do decide it is one or the other then it maybe worth doing both if you are lookin to keep the car. I have just finished my mates car where i reconditioned the head (new stem seals & guides, decoke & skim) and also replaced the piston rings and bearing caps. If you know your way around an engine than you can do it yourself providin you have the necessary tools.

Hope that helps...