Blow-by at 33K miles?

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skizot722

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Been a while since I posted on here, but I've got a few questions about my car. It's a 2002 V8 with about 33,500 miles on it. When I first got it, I noticed that oil was leaking out around the oil-filler tube in the driver's side valve cover. I figured that the o-ring gasket for the tube was damaged (even though the car only had 18K miles on it at the time), so I decided to replace it. That was a major PITA, and it's still been leaking since I did that. It stayed clean for a short while after I replaced it, but it didn't take long for the valve cover to start getting dirty with oil. The oil is definitely coming from where it seats into the valve cover.

On a side note, but I believe related, I keep getting P0133 (and the other 3 HO2S "slow to respond" codes) randomly. I even replaced one of the O2 sensors thinking there was just something wrong with it. But, over time I've gotten one for every sensor. I checked the service manual for possible causes, and one of them was to check the MAF sensor and gasket. I did this, and found nothing wrong with either (visually, haven't had the voltage on it checked yet). In the process of taking the air intake tube off, I noticed on the other valve cover (passenger side) that there is oil coming out of a tube that goes from it to the throttle body. On the valve cover, it is dirty with oil where this tube goes in at. And, I noticed that there was oil in the throttle body (I actually got a good dab on my finger when I felt around inside of it).

I'm thinking that oil being taken in through the throttle bottle might be causing the O2 sensors to trip up. But now, the bigger question, why is there oil blowing out of these openings on the valve cover? I know that excessive blow by can cause this sort of thing, but there's no way I should be having ring failure at 33K miles (let alone 18K when I first noticed oil coming from out around the filler tube). Now, I noticed that the V8 doesn't have a PCV valve, but it would appear that this tube going from the passenger side valve cover to the throttle body is acting as one (except that there is no one-way check valve, like you have with a PCV valve).

Can anyone give me some thoughts as to what's going on here? This is a really strange problem, and I have a hard time believing that it's blow-by, but I don't really have another explanation for the type of pressure that would be needed to cause oil to be forced out of these openings. Here are some pictures of what I'm talking about:

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this is fairly normal for the V8 - they all seem to have crankcase pressure, which finds it's way out through the o-rings of the filler neck, PCV tubes, VVT solenoid (Gen2) and is the reason the spark plug o-rings fail and allow oil into the wells.

It's also one of the bigger issues we have to deal with when adding the turbo or supercharger.
 
With the engine running (at idle) take the oil filler cap off. Does air blast out at you, or does it seem like there is no air coming out, maybe even a little going in? If it's the former, then you do have a ring problem. If the latter, then it's okay and you don't have any blow-by problem. Slight dampness around the crankcase hose connections is normal for most cars. As Quick says, some pressure does build at high power levels.
 
in the first two pictures it does not look like that hose connection in all the way in the valve cover.
 
it is - the hose actually clips onto the end of that nipple coming out of the valve cover. The nipple itself is popped through the valve cover, and like the filler tube, is a tight fit but not perfect and hence seeps oil.
 
Quik LS said:
this is fairly normal for the V8 - they all seem to have crankcase pressure, which finds it's way out through the o-rings of the filler neck, PCV tubes, VVT solenoid (Gen2) and is the reason the spark plug o-rings fail and allow oil into the wells.

It's also one of the bigger issues we have to deal with when adding the turbo or supercharger.
Click to expand...
Thanks. You're saying that that amount of pressure (enough for it to put oil into the throttle body) is normal on these engines? That seems strange to me, like something that would have been caught in the testing phase of engine design. Oil going into the combustion chamber isn't a good idea. Come to think of it, there have been a couple (just 2 or 3 times since I've owned the car) of times where I got a bit of oil smoke when I started the car. I'm now thinking it was because of the oil that had been pulled into the throttle body from the valve cover tube (I've already replaced the valve cover gaskets [and COP o-rings] when I replaced the filler tube and o-ring).

Do you have any ideas what would be causing the continuous O2 sensor trouble codes?


joegr said:
With the engine running (at idle) take the oil filler cap off. Does air blast out at you, or does it seem like there is no air coming out, maybe even a little going in? If it's the former, then you do have a ring problem. If the latter, then it's okay and you don't have any blow-by problem. Slight dampness around the crankcase hose connections is normal for most cars. As Quick says, some pressure does build at high power levels.
Click to expand...

Thanks, I'll try that. The old engine I had in my Chevelle would blow the PCV valve straight out of the valve cover when I got on it; boy was that engine worn.
 
Both of mine make to the 5000 mile oil change without any detectable oil consumption. What is your oil consumption rate?
 
The 5.7 and 6.1 HEMIs, as I've come to find out, have that same problem with oil pooling in the back of the intake. The fix is to install a "catch can" or oil separator in between the PCV valve hose. Maybe try getting a universal one to work on the LS?
 
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