05-21-09, 10:53 PM
Im new and have searched at great length on this issue but did not realy find the answer I was looking for. I just picked up a used 95 STS with 176k. In doing a tune-up i was cleaning the TB and noticed how bad my intake behind the TB was. I saw threads on how to clean them and that they get really dirty in these motors but I had up to a 1/16 of an coating inside the intake of oil and junk, most of the sticky variety. Would this be normal on a car that may have never been cleaned out before? A new motor was installed around 100k, so is it 75k of neglect? Or is this a sign of more serious problems? How is this junk getting in? Through the pcv system? If that is the case can I just install breathers on the end of the pcv and plug up the intake side?
(Learning how to be a American car owner for the first time)
95 STS N*
98 Nissan Sentra SE SR20DE-T
05 Yamaha FZ-1
05-21-09, 11:40 PM
That's pretty much normal. The car is 14 years old, of course there is going to be some build up. Yes it's probably from the PCV system, but I don't know what will happen if you convert the system. I would just clean it and leave it. The gunk doesn't appear there overnight. If it did, then I would be looking for something to fix.
Also :welcome: to the forums! :wave:
05-22-09, 09:19 AM
The oily buildup is the nature of the beast: The PCV system ventilates the crankcase and valve covers to remove all that stuff from inside the engine. When it gets to the intake manifold the gasses are hotter than the manifold, so some condenses on the inside instead of being burned, as designed. Don't modify the system as you'll leave the acids and vapor in the engine, and the airflow sensors are calibrated to accept the metered PCV flow.
About a year and a half ago, AJxtcman did a thread titled "A river flows through it" (weird title......) which explored the early Northstar PCV system and the oil baffle in the rear cam cover which sometimes loosens and allows liquid oil droplets to be sucked into the intake manifold. You can fix the problem, if it exists, but you have to remove the rear valve/cam cover, and you'll then wish you had never tried.
Add EGR gases to the PCV gases and you have the nasty, black oily mess which as everyone told you is perfectly normal and harmless.
05-22-09, 10:09 AM
The problem is coming from the rear PCV valve, so I guess I am having that same problem, I will have to try to find that thread, valve covers don't scare me as much as to have to do a head gasket...
05-22-09, 10:39 PM
FIRST start the car and pull the beauty cover. Good flashlight. Pull the hose/pipe off the PCV valve/orifice tube and look in (Plug the tube with your finger, and be careful NOT to pull the other end out of the intake manifold fitting.) Have an assistant rev the engine to 3,000 a few times. Droplets or liquid oil spurt out ??? If not, forget it, put it all back together and drive happily.
If it ain't broke, don't fix it.