Well this is my First Civic, so i am wondering what is normal and what's not. I have a mechanical background but never got a chance to evolve my skills. but here is the (maybe) problem.

I traded my Jeep for this 94 Civic DX. I know it needs work but not as much as what the jeep needed so i went for it since i miss having a import (my previous was a Supra)

1st: I finally got a chance to "explore" and notice black soot coming out of the tail pipe. Now the car sat for a lil bit, not sure how long, so my first impression is that its just carbon mixing with some moisture in the exhaust. Not 100% positive that it is or not. Is there a definitive way to tell oil from just carbon residue/build up?

2nd: How much air flow should be coming out of the Oil fill cap. i am going to do a comp check to the motor as soon as i can find someone who has one i can use.

3rd: what would be the main cause for a clunking sound in the front. It does need a new driver side lower motor mount but this happens over bumps and real bad on gravel, so i am fairly certain it is in the suspension. It has Coil over shocks on it and stiffer springs since it was lowered.

All help is greatly appreciated! Thanks.

 

For #1, I am not sure what you see there at the pipe. Is there black stuff oozing out?

For #2, I have seen a testing rig to measure the amount of blow-by on aircraft engine, using airspeed indicator. I don't think you do this on automobile engines and don't think is really needed. Compression check will tell you some aspect/condition of cylinders on any piston engines.

For #3, I have no clue/idea.

 

the exhaust is a black soot. i now believe it is running rich.

 

So what you mean is the exhaust gas is sooty. And I guess you see the soot is collected on the ID of exhaust pipe. And hopefully, water is dripping from the pipe without the smell of coolant.

If you see black exhaust gas, you know it is running very rich.

 

Black stuff coating the inside of the tailpipe is often normal. If it gets all over the back of the car, or makes visible smoke while driving, there is a problem. If it runs rich, the computer should detect that and turn the CEL on. Make sure your CEL works with the bulb test when you turn the key on and don't start.

Normally, there would be a net vacuum in the crankcase due to the PCV system. If you take off the oil cap and hold a paper card over the hole, it should be pulled down with the engine idling. If not, check PCV valve and hose, or the engine is worn and has a lot of blowby.

 

the only time i have seen black smoke come out the back is at first start up. I will try the card trick to see what happens.