dead piston
 

my car smokes white from the exhaust as some of you know. and when you hold your hand to the tail pipes theres a pulsing of air rather fast, and it sounds like bub bub bub bub bub. but deep, sounds kinda cool i think. aside from that. the guy that did my exhaust today said it sounds like i either have a dead piston/dead valve or one is misfiring. which worries me, because when the engines running on the right side of the engine (me standing in front of the car, right side) there is a rattle that sounds like it coming from the valve cover. umm. also from time to time when i get to about 45mph,(pushing it WOT) i can hear a knock, maybe 3 times and then that it. it doesnt continue after i let off. i dont do that often at all and it doesnt happen often at all. wat do you all thing. im thinking maybe a valv spring is off and there isnt proper combustion in a cylinder. or something of that nature. please help. i wanna fix this before their is too much damage. which is ok, if their is cause im never getting rid of this car lol. i just dont want it to break down, cause i just bought it and it would be dissappointing lol. so help please if you have a definitive idea.

RE: dead piston
 

White smole is indicative of water in the combustion chamber. It could be a leaking intake manifold gasket, a bad seal around the water jackets (on the intake manifold gasket) or worse, a blown head gasket or a crack in the cylinder wall somewhere.

The pulsing that you hear and feel,that's normal. Any engine will do that if you hold your hand on the tailpipe, if it's not too hot. All that you're feeling is the engine running through it's firing order.

Theonly true way to tell if you have a dropped cylinder, or as you say, dead piston, is to run a commpression test on the engine. If one cylinder's measured numbers are quite a bit different than the others, then you have at least identified the problem cylinder and you have to investigate futher.

Pull your valve covers and look for the obvious. A loose recker arm, a broken valve spring retainer, a bent pushrod and the like. The white smole will still be unrelated though. It WILL be caused by some form of water getting into your combustion chamber.

RM

RE: dead piston
 

well the white smoke deal is odd. because it only smokes when i start the car. on every start. but never after the start. the car runs rather well. which makes me ponder on all of this. it runs great atually. hesitates from a vacuum leak. but other than that its great.

RE: dead piston
 

You live on the coast where the humidity is high. Probably condensation in the exhaust sysyem. Common problem in high humidity areas.

RE: dead piston
 

Grab a vacuum gauge and hook in to a intake vacuum port and see what the gauge is doing.

low vacuum, pulsating, slow rythm up and down, there are certain things to look at on a vacuum gauge that can give you a really good idea of if you do have mechanical problems. Which is what it sounds like you have.

here is a link to to illustrations on what a vacuum gauge says to you with certain mechanical problems.

http://www.secondchancegarage.com/public/186.cfm

RE: dead piston
 

Did you ever check the plugs to see what they look like might give an indication.

RE: dead piston
 

Willie,

I hate to say it, as I did when someone else posted this link. But that information is a bunch of BS. There are too many normal situations where those types of vacuum readings can be present and nothing is wrong with the engine.

My 427 had only 7 in.mg. at idle and there were no vacuum leaks or bad/sticking valves in it.

RM

RE: dead piston
 

all my plugs are brand new. as well as the wireset and the cap and rotor. did it about 3 weeks ago.i think if my head gasket was blown it would smoke all the time.but i will pull the valve cover within the week and see what i see. guess i will get new valve covers when i do it, cause the ones on it are ugly.

RE: dead piston
 

Normal situations a vacuum gauge is the easiest and fastest way to diagnose the health of a motor without pulling plugs, covers, or anything else apart. Normal siuations.

A 427 with 7 in at idle isn't a normal situation. So you'll know the health of the motor is ok at 7. Now you start getting issues comparing to the known good to what you have may present something.

I've used a vacuum gauge for years and once you get used to seeing whats normal and what isn't normal it is a nice tool to use in the process of diagnosing a problem. And many of those situations where the motor does seem fine can show the expected health of a motor. With The quality of convertors on todays cars smoke out the tail isn't the norm unless the motor is really going south. A quick check of cranking vacuum, exhaust vacuum (to look for a plugged cat) and the engine running vacuum can tell how good a engine may not be.

RE: dead piston
 

If it just smokes on start up then it may be your valve guid seals letting oil seep by while it sits. Are you losing coolant? Does it idle and accelerate fine after start up? My 84 chugged on start up and cleared up (but with black smoke). It was a spark plug wire corroded and broke. But to computer was able to compensate enough to make it run fine when warm.
The knock you hear when pushing WOT is from your ignition timing and it goes away because the computer adjust the timing. Do you use low octane fuel?
A guy that builds top fuel dragster engines showed me what a bad valve sounded like when you put a hand up to the tail pipe. It was kinda a piff noise in with the bub bub. But its hard to explain. One mans piff could be another mans bub.