What bad things can happen from haveing a open crankcase ventilation system? - Page 2 - PeachParts Mercedes-Benz Forum

Diesel911 · #16 06-02-2018, 08:06 PM

Quote:

Originally Posted by Mxfrank

The PCV is probably on the opposite valve cover. All that would happen with this doohicky being disconnected is that air would flow through the oil fill hole, through the engine, and into the PCV, which is pretty much what normally happens. The PCV valve will prevent the manifold vacuum from becoming depleted, regardless of whether the crankcase is open or closed.

If a lot of oil splashed out of that hole, you may have been running the engine low on oil. Dirt could have gotten in here, but would probably be cleansed through the oil filter. Other than that, there's no way this would cause long term harm. Your emissions problem is something else. Possibly the PCV valve itself is defective, and that's why your fill hose blew off. I'd start by replacing the valve.

I need to recheck how PCV valves work but I believe in the face of an opened end vacuum is supposed to pull the Valve against spring tension and close off the flow.
But, that is in general I have to look up this prticular PCV valve.

It is a push rod engine so there was no evidence of long term oil splash. Although I did smell oil vapor for at least 6 months. Also I seldom drive on the freeway which would reduce the chance of Oil coming out.

Sugar Bear · #17 06-02-2018, 08:34 PM

Your PCV valve operation understanding is correct. Definitely check for vacuum to the valve though and see if the valve rattles. Check that it is EXACTLY the correct valve by part #. Seen excessive oil consumption due to the wrong PCV valve.

As for other sensor/computer concerns etc. I'm going with no related trouble codes unless the air intake was pulling in a lot of oily fumes. Did the air filter element look excessively oily?

There isn't a sensor to measure crankcase pressure so it couldn't have thrown anything off to the ECM.

Consider installing a new seal/grommet in the valve cover, secure the pipe and drive on. FWIW, the 4.3's are VERY good engines.

Good Luck!!!

Diesel911 · #18 06-03-2018, 08:50 PM

Well I pulled the O2 sensor and one Spark Plug. The plug did not look unusual and the O2 sensor had extremely black carbon on it but it was light and powdery and wiped off easily. Those seem to indicate a recent problem not a 6 month or more problem.

Have not pulled the PCV Valve yet but might get to that today.

oldsinner111 · #19 06-04-2018, 09:40 AM

in a non communist state,nothing but good things,clean intake,and valves.

Diesel911 · #20 06-05-2018, 04:18 PM

Well I am kind of embarrassed. There is a vent tube that goes from one of the Valve Covers to the Air Filter. That means the Crankcase is always exposed to the atmosphere. That means except for pulling in un-filtered Air into the Crankcase there is no difference if the Air comes in through the Oil Fill Tube hole or the Vent.

I pulled the PCV Valve and it seems OK but it is the original. Has Rochchester USA on it. Might replace it.

P.C. · #21 06-05-2018, 04:36 PM

Quote:

Originally Posted by Diesel911

Well I am kind of embarrassed. There is a vent tube that goes from one of the Valve Covers to the Air Filter. That means the Crankcase is always exposed to the atmosphere. That means except for pulling in un-filtered Air into the Crankcase there is no difference if the Air comes in through the Oil Fill Tube hole or the Vent.

I pulled the PCV Valve and it seems OK but it is the original. Has Rochchester USA on it. Might replace it.

If you shake it, can you hear that little steel ball rolling back and forth? If not, it's done...

Mxfrank · #22 06-06-2018, 07:01 AM

If the valve was clogged, it could cause excess pressure in the crankcase, and that could have been what blew your fill fitting off. Coulda, coulda, probably not, but it can't hurt to replace the valve.

JB3 · #23 06-06-2018, 07:19 AM

Im pretty sure that fill pipe has an associated bracket on both my 05 and 89 astros. Which would prevent it coming out like that. Is that disconnected/unbolted?

You biggest problem from this will just be the mess, and buring oil off the exhaust for a while.

Air&Road · #24 06-06-2018, 07:46 AM

The old road drat tube engines would gunk up in a heartbeat if not driven on long no runs that brought the oil temperature up for extended periods of time and the oil was not changed frequently. The poor oils of the day definitely aggravated the situations.

For the six month open engine, I would get that thing as hot as I could get it and pull the plug for an overnight drain. That would dod a lot to clean it out. Pulling the valve cover would tell you if it is gunned up or not.

Diesel911 · #25 06-10-2018, 06:22 PM

Well I have a new Grommet and new PCV valve to install. If I remember I will post a pic of the Oil Fill Pipe.
The single bracket is up front so you can indeed pull the rear out and in fact the Bracket was slightly bent. How it got like that I don't know.

Diesel911 · #26 06-10-2018, 06:25 PM

Quote:

Originally Posted by JB3

Im pretty sure that fill pipe has an associated bracket on both my 05 and 89 astros. Which would prevent it coming out like that. Is that disconnected/unbolted?

You biggest problem from this will just be the mess, and buring oil off the exhaust for a while.

My Engine is an 92 Vin W with the MFI (CMFI) Fuel Injection. More frequently encountered is the Vin Z Engine with TBI Fuel Injectio. It has a different air induction system and likely a different Oil Fill Pipe.

Diesel911 · #27 06-11-2018, 10:36 PM

Quote:

Originally Posted by Diesel911

Well I have a new Grommet and new PCV valve to install. If I remember I will post a pic of the Oil Fill Pipe.
The single bracket is up front so you can indeed pull the rear out and in fact the Bracket was slightly bent. How it got like that I don't know.

Well my memory is awful. see attached pic.

It is hard to tell from the picture but the lower 1/4 portion to the right of th pic actually makes a bend towards the viewer.

Diesel911 · #28 06-12-2018, 11:57 AM

Here is another pic.

The New Grommet and Oil Filter Fill Pipe are back on the Engine sealed again with Silicon Sealant as well as the new PCV Vavle.

Oddly the shadow in the picture makes it look like there is 2 brackets.