: Help! Stuck piston in n* I need help!

04-29-07, 11:13 PM
I took my '94 Eldorado touring coupe to dealer serv. becaouse all of a sudden it started smoking really bad, white smoke. They did a compresion check and it was OK 170 lbs. So they thought it was a piston the was stuck. They did a piston decarb twice and checked #8 cylinder with bore scope-- looked good. But when they road tested it again #8 plug still fouling and started smoking again. So I got a plug spacer to help the smoking. Does anyone know any tricks to unstick the piston? This is my baby I love this car only 80K miles and it's one of the few Polo additions, really stands out in a crowd. PLEASE HELP!!!!!! Thanks ahead of time to anyone who can help. Kay

04-29-07, 11:54 PM
You've been a member for 2 years. Surely you have heard of the WOT treatment? Go to the Technical Archives at the top left of this page and read up on "oil Consumption" and "Occasional Full-Throttle Acceleration Is Good For Your Engine". What you are describing is stuck piston rings. This procedure should free them up.

04-30-07, 07:55 AM
Since it is only one cylinder, it's more likely to be a valve seal. In a northstar, when they leak, they really leak.

04-30-07, 11:33 AM
Good point.

04-30-07, 03:42 PM
White smoke usually signals coolant in a cylinder, doesn't it? Blue smoke is oil, and black smoke is rich (fuel) mixture.

04-30-07, 04:20 PM
White smoke usually signals coolant in a cylinder, doesn't it? Blue smoke is oil, and black smoke is rich (fuel) mixture.

Normally yes..... but it's easy to get the colors confused if you've never seen it before. Since the plugs are getting fouled, it is almost certainly an oil issue.

04-30-07, 04:46 PM
If the valve guide seals are leaking the engine will put out a puff of blue smoke after engine braking or idling. Under power the exhaust is clear. Leaking rings make smoke under power.

04-30-07, 07:26 PM
White "smoke" can also be unburnt fuel vapor (excessively rich).

04-30-07, 08:53 PM
This is comical.
First it is a 94 and the instake is not plastic.
EGR passage? That would be a very good guess!
PCV system would be the #1 guess if it had a PLASTIC manifold because the pcv drops oil into the intake above #8 runner.
If the plug is oil fouled then I would look at the EGR passage. You will need to remove the intake to clean it out. You may need to remove the cross over and clean it out also. TSB?
ZMAX is now a recomended ring cleaner from GM

05-01-07, 09:42 PM
What's up? No one seems to agree on anything. Let me clarify a few things. Realy heavy cloud of white smoke, not like when it's burning rich. Smokes under power but more when braking and idling. Even after the engine is turned off a small wisp of smoke keeps coming out for a minute or so. The spacer in the #8 plug did not stop any of the smoke. So guys, now what? Thanks, Kay

05-02-07, 12:36 AM
Does the smoke smell like oil or fuel?

05-03-07, 10:49 AM
Hope you have a wallet full of money or a real honest mechanic or both. Northstars are sometimes not cheap to fix.

05-03-07, 08:58 PM
Have somebody hold a piece of cloth over a tailpipe while you goose it a couple of times. See what shows up on the cloth. A blind man ought to be able to tell whats coming out and making the smoke.