PCV Module Inspection/Removal, Oil Leaks, Excess Crankcase Pressure
 

Please note, I referred to the Upper Plenum as the Upper Intake in these photos. Only the Upper Plenum and the runners need to be removed (not the upper intake with the fuel injectors) to gain access to the PCV Module which is located on the rear (drivers side) of the engine attached to the block mid way down. It is tight against the engine attached with four bolts and atv (no gasket). You can see these bolt from the top looking down under bright light.

If your 3.0L Saturn starts to puke oil out of valve cover gaskets and other gaskets, it is likely due to the reed valve inside the PCV Module is broken which results in excess crankcase pressure. I can't tell you exactly how the PCV Module functions but there are two engine ports which the module is bolted above and two vacuum lines to the intake located at the front of the engine. The small diameter vacuum hose has a push on connection to the PCV module routed up underneath items bolted to the top of the rear runner. It is interleaved together so take time to pay attention of the routing(s) so reassembly is made easy. The larger diameter hose is clamped on to the PCV Modular and routed up to the plastic bridge held on with another clamp that is seriously hard to get to much less disconnect.. The plastic bridge connects to a small hose and to the intake on the passenger side of the engine. When the reed valve breaks, these hoses and the PCV Module become plugged with gunk. Once the hoses are plugged, the crankcase pressure blows out the gaskets at the weakest point.

Below are photos showing the location and type of fasteners used for various parts as you disassemble to access the PCV Valve for inspection and/or DIY rebuild. I have more photos on the rebuild process and I will post them at a later date. All the parts interleave considerably and at first you think it is impossible to remove the upper plenum and the EGR base as one piece, but it does come apart just like I say. There are many more items that could be taken apart, but is unnecessary to do so. The few parts you disassemble the better.

https://cimg5.ibsrv.net/gimg/www.sat...f146ee3dd6.jpg
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Note: I referred to the Upper Plenum as the upper intake by mistake.

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Note: I referred to the Upper Plenum as the upper intake by mistake. Also, the left most runner intake clamp was marked blue and should be red.
https://cimg1.ibsrv.net/gimg/www.sat...f3177054b9.jpg
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Note: I referred to the Upper Plenum as the upper intake by mistake.
https://cimg9.ibsrv.net/gimg/www.sat...dceee819c5.jpg
Note: I referred to the Upper Plenum as the upper intake by mistake.
https://cimg2.ibsrv.net/gimg/www.sat...b42824f2a5.jpg
https://cimg4.ibsrv.net/gimg/www.sat...d30a9a1d3e.jpg
Note: I referred to the Upper Plenum as the upper intake by mistake.

When lifting up the Upper Plenum, take your time and if something is holding it secure... there must be another bolt holding it on or something is in the way. It takes some work to wiggle the entire Plenum and EGR base free, but it will come off. All these parts and modules are interleaved together and I believe NO Thought was given toward future maintenance. Hence the lack of detailed information in service manuals. I hope this helps because it was a bitch to learn that much is for sure!

Our Saturn is a 2000 LS2 L300 with a 3.0L engine. I suspect any Saturn's still on the road today will endure a failing PCV module/crankcase pressure issue as well. Don't be tricked into thinking a few gaskets have gone bad without first inspecting and/or rebuilding the PCV Module. If the crankcase pressure is extreme... no new gaskets can withstand this pressure and will leak in short order. If the gaskets are guru set... meaning atv the hell out of them... the next path to release pressure will most definitely be the front main seal. So fixing the PCV Module is key to keep from leaking a quart of oil a day and/or becoming an oily flaming torch destine to the junk yard!

Very nice writeup, thank you. This should help many L300 owners. And one more reason I love my L200.

Thanks for going through all of that typing and posting. IF I ever purchase another Saturn, I think I'll just hang with the 4 cylinders. The older I get, the lazier I'm getting and I don't want to have to fool with all that on a V-6 engine. Slow and steady, that's become my lifestyle. You did and awesome job and an awesome posting here, Stick around, please. The forum can use people like you for sure!

Thanks for the compliment! The V6 really does burn your back, bust your knuckles and put pain where none belongs, but when they are running right... they are really fun. Shouldn't the value of these 20 year old cars start increasing already? LOL Our car still looks great... too bad it doesn't run great! But, I'll figure it out eventually!

Probably a foolish question to ask, but have you ever tried any of the Techron Fuel System products? I've used it for years and have NEVER had a fuel system delivery problem. I use a bottle of Techron Fuel Injector treatment every 10,000 miles in my car and every 25,000, I'll put in a bottle of the Techron Fuel System cleaner. It's good stuff. I don't know if it'll help the way your car runs, but it's cheap enough and after a few hundred miles, you should know if it's doing anything for you or not.

I finally received a code reader. I learned the O2 Sensor B2, S1 was open. Immediately I thought perhaps I might have disconnected it and forgot to reconnect it... no such luck, the connector is connected and the cable is fine, no damage. So now I have to decide if I should purchase a sensor. What are the chances an O2 Sensor would go bad while I was working on it. Perhaps all the crap I sprayed in the intake(s) fouled it up. I don't know. I am still learning how to use the Ancel 410. The other code was random misfires, but I believe if the O2 sensor is out, it can cause poor idling.

Please post the actual codes. Like p0300 is randoms fire. Any other misfire codes P03XX?

You mentioned bank two sensor one so that is the front sensor from the bank of cylinders with number one on it. So bank two would be the bank with cylinder two on it.

Depending on mileage, poisoning by oil burning and other contaminants, unburned gas, etc it is not hard to trash and oxygen sensor. Just make sure you identify the correct one. If your new scanner has real time data monitoring capabilities, you can observe the behavior of the voltage generated by the oxygen sensors in real time and compare the front versus the rear for each bank and see if there is a difference between them (for starters.)

Most oxygen sensor codes are not phantom codes. If a oxygen sensor says it's open, you can easily confirm by seeing there is no voltage output after ensuring it is not an electrical issue with a nicked wire, etc. One of the many handy uses of this type of tool

The codes are...
PO154 - O2 Sensor circuit no activity detector Bank 2 Sensor 1
PO300 - Random/Multiple cylinder misfire detected

I verified the cable of the O2 sensor near the radiator is connected.

I suspect I need to buy an O2 sensor. Should I buy two for both exhaust manifolds? I believe they are the same sensor, correct? And, before and after the CAT are different and both different from one another.

When I cleaned the intakes, I know I got gunk and spray in the engine because it was very difficult to start. The O2 sensor could have been fouled up and now doesn't work. Do you agree?

Pull all three plugs on bank two. Pull one plug front bank one. Do not get them mixed up between banks or which cylinder goes with which plug.

Misfires can happen for a number of reasons. Step one is examining the plugs to see if they are fouling. Can be gas fouled, oil fouled, etc. Please take a picture of the plug from Bank one and all of the plugs from bank 2.

Other potential sources of the misfire are issues with the coils, intake manifold gaskets, etc. Start with the easy stuff and rule it out.. check the gaps while you're in there.

Vehicle will always be difficult to start with all of the cleaner and scuz already in the intake. Can never say for sure what kills an oxygen sensor.

Also, you have verified the connection but the code nominally indicates no activity from the sensor. I need to look up the code and see exactly what triggers it to figure out whether you could still be an electrical issue or if it is simply not sensing anything anymore.
In general the front sensor is different from the rear sensor as far as parts go. I believe your vehicle has a front and rear O2 for each bank of cylinders.

So sensor one bank one is the front O2 for the cylinder bank with cylinder one in it. Sensor two bank one is the rear O2 for the cylinder bank with cylinder one in it. Same deal for bank two respectively.

Resist the urge to run out and throw parts at it. We will get there

I picked up an O2 sensor at auto store, but paid way too much for it. I have it in hand vs buying on Amazon with their stupid descriptions which make no sense. I think they reverse the meaning of Upstream to be the lower O2 sensors and I don't want any part of having to return a part which was fulfilled wrong!

It was too cold to replace the O2 sensor. I did crack the bad one loose. And I have to charge the battery.

I literally just cleaned the plugs just before this latest two or three startups. The plugs were dark, but not fouled. Just what I would expect from trying to start the engine with cleaner in the pipes etc...

The weather doesn't look any better tomorrow! So I might just allow the battery to charge for a few days and then replace the O2 sensor and give it another start.