Nissan diagnoses

[Gumby]

I've got a 95 Nissan 200SX SE with the 1.6L DOHC motor.

It was donated because of a bad head gasket diagnoses. I changed the head gasket and the leaking water pump. The head gasket was fine. The head checked out visibly and there was no other indications of a leak. The combustion chambers were equally and normally dirty. There was no "steam cleaned" pistions.

It smokes badly intermittently. I can understand the diagnoses, because it pukes clouds of whitish smoke.

It only smokes when warmed up. It might only smoke in closed loop, but I haven't been able to verify that. It smokes at an idle when revved. Clears up at speed.

The smoke smells strange. It's not antifreeze. It's not really oily.

It is not pulling brake fluid in the vacuum hose. It does not have a vacuum modulator to pull trans fluid in. The PCV was plugged, but cleaning it does not make a difference.

It's non-turbo. It's not turbo seals.

No one cylinder makes a difference. I pulled the plugs and injectors one at a time. No difference.

It spark knocks badly when it's smoking. Not at all any other time.

The timing advance goes from 0 to 64 degrees when it's not doing it, 0-4 degrees when it is. No fluctuation. it's either 0 or 64 degrees. All other data from the datastream is normal.

Plugs are slightly sooty. None are oily, crusty or different from any other.

There is dark black oily gunk coming from the exhaust. Just a little spray. The oil is new, of course, and the inside of the engine was sludge free.

I'm stumped. I found one similar problem on the web in a ford/mazda Ranger, but nobody answered the guy's question.

Any eye-deers?

 

[72FJ40LandCruiser]

Cracked head? Did you magnaflux it?

 

[Gumby]

Aluminum head. Magnafluxing wouldn't work.

I did not have it cleaned and pressure tested. I was trying to keep costs down and there was no evidence of contaminents in the combustion chambers.


I sure don't want to tear it back apart without some evidence that it's leaking.

 

[2badfjs]

head temp sender 22630-41b00

 

[DBAX]

Gumby Pm

 

[Gumby]

head temp sender 22630-41b00

really? why?

 

[2badfjs]

really? why?

tells the computor that the engine hasent warmed up so it sends a signal or no signal that the engine is still cold.
to much gas and running rich

just a thought

and the last series of 5 in the part number might not be right.
22630- is the beginning of that part #

 

[PabloCruise]

Any oil leaks on that 1.6L?

 

[beaufort-fj60]

sugar in the gas tank?

 

[GUAC]

Aluminum head. Magnafluxing wouldn't work.

I did not have it cleaned and pressure tested. I was trying to keep costs down and there was no evidence of contaminents in the combustion chambers.


I sure don't want to tear it back apart without some evidence that it's leaking.

Liquid penetrant

 

[Gumby]

tells the computor that the engine hasent warmed up so it sends a signal or no signal that the engine is still cold.
to much gas and running rich

just a thought

and the last series of 5 in the part number might not be right.
22630- is the beginning of that part #

Good thought. I checked this morning and the ECM is reading ambient temp for coolant temp before start up and warmed up normally to 195F

 

[Gumby]

sugar in the gas tank?

I thought about that. That or maybe diesel in the tank.

I took a fuel sample this morning. Nothing conclusive from just looking at it. I might just drain the tank and put some known good fuel in it.

 

[Gumby]

Checked this morning.


I disconnected the EGR, the charcoal canister and the intake cam timing adjuster.

Still smokes, but doesn't seem to spark knock any more.

My problem with EGR or EVAP is that those things whould work at steady cruise and not rapid accel, which is where I'm getting the most smoke.

Double checked for coolant lines to the intake. There are none. No heated t-body or anything.

Pulled the valve cover. The oil drains down the timing chain cover and the holes are not impared at all. No real sitting oil in the head.

 

[Gumby]

Came in this morning ready to pull the head and the sonofabitch held 15 psi of pressure on the cooling system for the last 12 hours.

I'm freakin stumped.

 

[beaufort-fj60]

crap in the cat? does it have a fart can muffler?

 

[PabloCruise]

Good thought. I checked this morning and the ECM is reading ambient temp for coolant temp before start up and warmed up normally to 195F

What about when it is acting up and smoking? Still read 195?

 

[Gumby]

Good thought.

Regular muffler. Nissan factory, in fact. I just replaced the cat to muffler pipe.


I've been running it all morning and it won't smoke.

I put a coolant pressure tester on it and ran it for an hour. It never got about 10 psi, didn't leak down, didn't smoke and ran about 200 degrees. Every so often I go out in the shop and rev it, but it won't misbehave.

I'm gonna let it run for a while longer, then drain the remainder of the gas out and refill with known good.

 

[Gumby]

What about when it is acting up and smoking? Still read 195?

Yup.

 

[Gumby]

Pulled the PCV and let it run with the valve just sticking in the air.

No smoke.

Put in a new PCV - smoke.

Pulled the fresh air intake line off of the intake tube thinking the line was plugged and the engine was getting so much negative pressure at idle that it was pulling oil into the PCV. Not plugged and worked as it should. smoked with the line disconnected and the engine pulling air right in the hole in the valve cover.

Drove it all over with the PCV off and no smoke.

I'm thinking the baffles in the valve cover are messed up or some such. maybe the vent passage from the crankcase to the head area is plugged.

happy to not be pulling the head back off.

 

[beaufort-fj60]

does the plumbing go from crank case to intake, and from air box to pcv in valve cover