I just bought a 96 Dodge Neon (SOHC) with an Automatic transmission from my friend. The car has 132,101 miles on it and is blowing out some white smoke from the exhaust which smells pretty bad too... It has a knocking sound coming from the engine somewhere you can hear it welllll at idle.

What could the knocking sound be? Is it worth swapping a manual transmisison in and doing a bottom & top rebuild? Or should I get a new engine or a new car?

 

the knocking could be improper gas in the tank, or a mini-backfire. What kind of gas are you running in there right now? The Neon should be taking 87 or 89 octane, unless he's had some performance upgrades done to the car (in which case you'll need to be running premium gas). Have you tried replacing the spark plugs and wires? Don't run platinum plugs (those are horrible for the Neon). Is the check engine light on? Try getting the trouble codes from the vehicle by turning the key forward and back 3 times within 5 seconds. This will cause the check engine light to blink (get a pencil and paper). It will blink a few times, and then pause. This is the first digit. It'll blink a few more times, and then pause, this is the second digit. If it blinks more than that, that's a whole new trouble code. Write them all down until you see code #55 come up, that means "end of all codes". Alternatively, you could get a reader and get the codes from your car that way. Let us know what codes pop up and we should be able to help you from there.

 

white smoke in the exhaust...blown head gasket, the 1st gens are noted for it, do to the fact that you have white smoke and a knock, i would say it was run like that for awhile and was overheated WAY to much past the danger zone, and the knocking is most likely a rod, sounds to me the motor is shot, if you don't have a lot into it allready then a rebuild will run around 1k and the tranny swap isn't that bad of a job. if you are looking for a rat, look for something else, if your looking for a fun little ride you can build on, then you have a good starting point, my family and i are currentley starting a build on a 96 coup that was in about the same shape(but not as good as yours lol) and it is turning out to be a fun project. good luck, let us know what you find out.

 

im going to go grab the trouble codes right now.. and good luck on on your neon project ramrat... im definatly putting new gaskets in sunday

 

got the trouble code 124431 and it pushed out thoes 2 5's at the end.. What does that mean?

 

12 Direct battery input to PCM was disconnected within the last 50 key-on cycles

44 Battery temp sensor volts out of range

31 Evap purge flow monitor failure or evap solenoid circuit

thats what I found... if thats right... what is an evap purge flow monitor failure? and could any of them cause a knock or white smoke? Im hoping so...

 

Excessive white smoke is usually due to water being burned/evaporated in the combustion process. This is most often due to a blown head gasket. If enough water is getting into the cylinder(s) or any other oiled part of the motor it could cause the bearings to spin or the engine to lock up. If this is the cause of both the smoke and the knock, then when you pull the oil dip stick it should show up as creamy in color, like a brownish white cream or froth instead of clear to dark brown like the oil should be normally. Check the oil right away.

How does the exhaust smell, exactly? Does it smell like antifreeze (a sign of a blown head gasket)? Does it smell like rotten eggs (a sign of a plugged catalytic converter)?

 

what could cause a code 12 on my 99 dodge neon sport 2.0DOHC and how do i fix it ? any ideas,,any 1!!! please help!!!

 

71 is right, sound like a blown headgasket I had the a lot of white smoke coming from my exhaust and the oil was milky, other symptoms could include no heat, and even antifreeze gurgle coming from where you put in your antifreeze, deepending on how long you may have drove it and noticed the white smoke could explain the knocking, I drove mine past the point and cracked the head all during the nice winter months, The machine shop did a nice job on my head polishing it up and smoothing it out, then I had them put on a good headgasket set and while they where at it I had them put in my header hopefully everything works out for you

 

12 is nothing to worry about, just saying the battery was disconnected not to long ago, that will reset itself soon enough, and the 55 means end of codes