hey guys. I picked up a fairly nice 89 formula for cheap because it wasn't running right. its acting like it has a bad vacuum leak so while I was looking things over with the air cleaner off and car running I put my hand against the breather tube and it has a large amount of vacuum. I plugged it and my rpms dropped back down to 800 from around 1500. car is running better like this but still not right. my question is how do I have vacuum here?

 

suction there is normal.but the drastic RPM change plugging/unplugging the breather is not-might have bad or missing PCV valve.

 

Yeah, I'd try a fresh PCV valve AND INSPECT THE HOSE GOING TO IT FOR CRACKS, HOLES OR GENERAL DETERIORATION. At idle the PCV valve shouldn't be moving enough air out of the engine to cause such a huge RPM drop just by plugging the breather hose on the other end.

 

I mean a lot of vacuum guys like it would suck a rag in I don't think the small hose going to the pcv could even produce this much at the much larger vent hose. but I know this hasn't always been the condition because when I got the car the filter housing had oil in it and the filter its self was nasty. all I have done so far is set the timing clean the housing and replace the air filter changed the oil and replaced the o2 and intake air sensors
and put a new throttle body and gaskets on the intake

 

Sounds like you got a real big intake manifold leak, bad gaskets or big crack, like your manifold vacuum is getting into the valley area of your block

 

oil in the air cleaner housing, is a sign of your crankcase ventilation system being out of order.PCV and hose needs to be right .as stated by others. if this continues to crop up .do a compression test on all cylinders.as you may have way too much "blowby". does it blow blue smoke? how do the plugs look? are they oil fouled? if this is the case ,youre in for a rebuild

 

it blows smoke on startup but not really after that. I know the motor is tired it has 144k on it and im sure they wernt nice. was hopping to be able to drive it for a bit though

 

Sounds like its time to pull the intake and replace intake gaskets to me and inspect the manifold for cracks.


As for PCV.....I prefer using fixed orifice PCV valves for say a 2003 5.3 Tahoe. They don't rattle at idle and IMO its a better setup.

 

ok Im not sure how they work so here is a thought I also removed my cat while problem solving to see if it was plugged. would having the tube that comes off the cat for the AIR system wide open cause any kind of vacuum?

 

No, time to pull your intake manifold for a look,see