oily air filter and a bad idle but smooth ride

[Wags391]

This is what I've recently done to my 92 S-10 blazer 4x4 4.3L Z:

Radiator, oil pump (installed high flow), pump shaft, manifold gaskets, rebuilt TBI, and the starter. All that in 5 days. Not a fun week.

Now I am getting a large amount of oil in the air filter and my idle is very rough at stops. I replaced the PCV valve and hose. Also, the breather grommet and connectiing hose. I just did the oil pump this last month (Jan.) and yesterday there was almost no oil on the dipstick when I checked it. My remote oil filter lines are leaking but not that bad.

So, I'm still getting oil in the air filter and my idle sucks. Idle could be the cat or EGR, but there is not a bad smell from the cat.

Thank you.

Wags

[Wags391]

**I should have posted this here first.**
(Also posted in the main forum)


This is what I've recently done to my 92 S-10 blazer 4x4 4.3L Z:

Radiator, oil pump (installed high flow), pump shaft, manifold gaskets, rebuilt TBI, and the starter. All that in 5 days. Not a fun week.

Now I am getting a large amount of oil in the air filter and my idle is very rough at stops. I replaced the PCV valve and hose. Also, the breather grommet and connectiing hose. I just did the oil pump this last month (Jan.) and yesterday there was almost no oil on the dipstick when I checked it. My remote oil filter lines are leaking but not that bad.

So, I'm still getting oil in the air filter and my idle sucks. Idle could be the cat or EGR, but there is not a bad smell from the cat. Any ideas?

Thank you.

Wags

[herkyhawki]

check the crankcase fresh air inlet in the other valve cover.

[old_master]

Only one thing will allow oil to get into the air filter: Blow-by gasses traveling out the PCV inlet tube and into the air filter. This could be due to insufficient vacuum to the PCV valve, wrong or faulty PCV valve, clogged oil return passages in the engine, worn, broken or leaking piston rings. Bottom line is that the blow-by pressure is greater than the PCV system can handle in its present condition.

[Wags391]

Originally Posted by herkyhawki

check the crankcase fresh air inlet in the other valve cover.

I replaced the grommet and the hose, but still the same problem. It's never done this before. Of course, I just put in a new oil pump and intake gaskets. The internal vacuum and pressure is greater than before.

[Wags391]

Originally Posted by old_master

Only one thing will allow oil to get into the air filter: Blow-by gasses traveling out the PCV inlet tube and into the air filter. This could be due to insufficient vacuum to the PCV valve, wrong or faulty PCV valve, clogged oil return passages in the engine, worn, broken or leaking piston rings. Bottom line is that the blow-by pressure is greater than the PCV system can handle in its present condition.

So...How can I check the vacuum to the PCV? How can I check for clogged returns?

[herkyhawki]

Pull the fresh-air inlet hose off and observe if there is air flowing into or out of this port. If you have excessive blowby, you will see flow out of this port. If blowby is within the limits of the PCV system, you should notice a slight amount of airflow into this port.

Why did you install the high-flow oil pump??
Is it possible that now you are getting too much oil up in the valve covers? The air is the becoming saturated with excess oil right at the point where it is entering the PCV valve. If your PCV system is working fine, there may just be too much oil entrained in the air.

[Wags391]

Originally Posted by herkyhawki

Pull the fresh-air inlet hose off and observe if there is air flowing into or out of this port. If you have excessive blowby, you will see flow out of this port. If blowby is within the limits of the PCV system, you should notice a slight amount of airflow into this port.

Why did you install the high-flow oil pump??
Is it possible that now you are getting too much oil up in the valve covers? The air is the becoming saturated with excess oil right at the point where it is entering the PCV valve. If your PCV system is working fine, there may just be too much oil entrained in the air.

You know, I had some doubts when putting in the high-flow pump. I was told by those I asked that it would help with my oil pressure, which would run low (especially at idle), and cooling during the summer months (Texas). It seems crazy to re-replace it again with a standard, but that may be my problem. Would you suggest replacing it?

And honestly, my oil pressure isn't any greater than it was before. At start up, it runs a little over 40 and after warm-up it is under 40.

[old_master]

A high volume oil pump does exactly that, pumps more oil than a standard pump. Along with moving more oil, it should also increase oil pressure noticeably. It will have no effect on PCV operation unless the oil returns are clogged to the point that oil "pools" in the overhead area. High volume oil pumps were designed for engines with high mileage, usually associated with slightly larger clearances between engine bearings and journals.

While the engine is idling, remove the PCV valve from the rocker arm cover. Put your thumb over the hole in the valve, you should feel a very strong vacuum. If not, follow the hose back to where it connects to the intake manifold. Remove the hose and you should feel a very strong vacuum. If not, the intake manifold passage is clogged and must be cleaned out.

Checking the overheads for clogged oil returns requires the removal of the rocker arm covers and gaskets. There should be visible space between each push rod and the cylinder head. At the rear, outward corner of each cylinder head, there is a drain hole about 1/2" in diameter, it should be clear. The entire overhead area, including the underside of the rocker arm covers, should be free of sludge. Along with the process of cleaning out the sludge, goes a risk of sludge falling into the oil pan and clogging the oil pick up screen, (if it's not already). When the screen gets clogged, the oil pump can not draw oil from the oil pan, and the engine will seize up. The only safe way to clean sludge out is through complete engine disassembly. Sludge can build up for several reasons, the most common is too many miles between oil changes. Others include weak or inoperative PCV system, and engine operating temperature is too low. Short, around town trips can also increase sludge build up due to excessive moisture build up in the crankcase.

[ericn1300]

Originally Posted by old_master

Checking the overheads for clogged oil returns requires the removal of the rocker arm covers and gaskets. There should be visible space between each push rod and the cylinder head. At the rear, outward corner of each cylinder head, there is a drain hole about 1/2" in diameter, it should be clear. The entire overhead area, including the underside of the rocker arm covers, should be free of sludge. Along with the process of cleaning out the sludge, goes a risk of sludge falling into the oil pan and clogging the oil pick up screen, (if it's not already). When the screen gets clogged, the oil pump can not draw oil from the oil pan, and the engine will seize up. The only safe way to clean sludge out is through complete engine disassembly. Sludge can build up for several reasons, the most common is too many miles between oil changes. Others include weak or inoperative PCV system, and engine operating temperature is too low. Short, around town trips can also increase sludge build up due to excessive moisture build up in the crankcase.

Hey O.M. have you ever tried or, do you, have an opinion on those oil flush additatives you put in the oil before an oil change to flush out the sludge and contaminants? I've always wondered if they work, and what's your take on oil treatments like Slick 50?

[old_master]

Good question, Eric.
As I mentioned earlier:
"The only safe way to clean sludge out is through complete engine disassembly."

Most of those flush additives you're referring to are partially or completely kerosene. If you're lucky, the sludge will loosen slowly and not be a problem, but who's to say it will loosen slowly, and not release a big ole chunk 'o crud? (A quart of that stuff is around $5. You can buy a whole gallon of kerosene for around $3.) Bottom line...if the engine is sludged badly enough, it's just a matter of time and it'll buy the farm on it's own. You just might speed the process up, you've got nothing to lose by trying it.

As for oil additives: The chemical engineers at the oil companies develop a detergent "package" for a given oil. That "package" of chemical additives is designed to work best just the way it is. By adding anything to the oil, you can and most likely will, throw the chemical composition in to a tail spin. Unless you're a chemical engineer and know exactly what is in the oil, and how it will react to another chemical, you're best leaving it alone. If you're not satisfied with you're oils cleaning and/or lubricating abilities, find a new oil, and change it more often than you think you should! That alone will keep the inside of your engine as sludge free as possible. What do I use??? 5W30 Mobil One fully synthetic and a Purolator Pure One oil filter. Change the filter at 3,000 miles and change the oil and filter at 7,000. Yup, it's expensive, so is an engine overhaul.

[Wags391]

Would a clogged cat cause more back pressure to cause more blow-by to cause more oil going through the PCV system into the air filter?

[ericn1300]

Originally Posted by old_master

Change the filter at 3,000 miles and change the oil and filter at 7,000. Yup, it's expensive, so is an engine overhaul.

???? thats just opposite of what i've read. the toyota owners manual recommends changing the filter every other oil change

[old_master]

"Would a clogged cat cause more back pressure to cause more blow-by to cause more oil going through the PCV system into the air filter?"

I have serviced vehicles that the converter was restricted to a point the engine would barely idle and stall if the throttle was opened at all. Increase in crankcase pressure, (blow-by) was negligable. If crankcase pressure increases, it is an indication that the piston rings are unable to seal compression, (and oil). So, to answer your question, yes it could cause blow-by to increase. However, now you're assuming there are two problems, check the PCV system first, that is the most likely cause.

[Wags391]

Originally Posted by old_master

I have serviced vehicles that the converter was restricted to a point the engine would barely idle and stall if the throttle was opened at all. Increase in crankcase pressure, (blow-by) was negligable. If crankcase pressure increases, it is an indication that the piston rings are unable to seal compression, (and oil). So, to answer your question, yes it could cause blow-by to increase. However, now you're assuming there are two problems, check the PCV system first, that is the most likely cause.

The PCV valve, hose, breather hose, and both grommets are brand new. What else is there to check on the PCV system?