oily air filter and a bad idle but smooth ride

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

**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

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

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.

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.

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?

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.

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.

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.

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?

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.

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?

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

"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.

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?

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

That philosophy is WAAAAY old school. What year owners manual are you looking at? Oil and filter changes are the cheapest insurance policy you can get for your engine, why risk it?

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

Read the 2nd paragraph of post #8.

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.


Did this. PCV system seems normal. Suggestion for next step??

We need to determine if the oil is being burned, leaking, caused by blow-by, or a combination of these. You mentioned a rough idle, an oil leak, and oil getting in the air cleaner. Are you experiencing excessive smoke from the exhaust also? The next step will be to remove the spark plugs and arrange them on a workbench, etc, so you know which plug came from which cylinder. Inspect each one for oil deposits, (black, caked on porous material). You might find one plug worse than the others; in fact it may even be fouled out, (ground electrode bridged to the center electrode with oil deposits). This would explain the rough idle. If you do find one fouled, the next step is to have a compression test done on all of the cylinders, wet and dry. A cylinder leakage test would also be helpful. Pay close attention to the results, particularly on the cylinder that had the fouled plug. Without knowing the test results, it's impossible to determine exactly what's going on.

Sorry to interupt, but It seems you skipped right over the simple test I posted to check for blowby. Trust me it wil only take 2 minutes and will tell you alot.

herkyhawki,
Thanks, but he has replaced the PCV fresh air inlet hose and grommet. The only way oil can accumulate in the air cleaner is from blow-by entering through the inlet hose. He also has determined that the PCV valve has sufficient vacuum to it, which means the PCV system is ok, other than the possibility of restricted oil returns. At this point, the only thing that could possibly be stopping PCV flow, would be if all of the oil return passages in the left cylinder head were completely restricted, and whatever is causing the blow-by is in the right bank of the engine, forcing blow-by out the inlet hose. If that were the case, the left overhead would fill with oil and the PCV valve would suck oil. The odds of that are astronomically high, more like close to impossible. Pulling both the PCV valve out of the left rocker arm cover, and the inlet hose out of the right rocker arm cover; running the engine will give a true indication of blow-by. We already know the engine has a blow-by problem; the question is which cylinder(s).

We already know the engine has a blow-by problem; the question is which cylinder(s).

I'm going to pull plugs and do a compression test on Wednesday. I will post results then. What is the difference between a dry and a wet test? And what is a cylinder leakage test?

Also, to answer a previous question: No, I am not getting excessive smoke. There is no smoke at all really to suggest burning oil.

Wet test... a small amout of oil shot in the piston through the spark plug hole first..
Cylinder leakge.. when the pressure is up .. how fast it bleeds off..

Good Luck

Remove all of the spark plugs, disconnect the connector at the ignition coil to disable it, and prop the throttle open. Run a compression test on all cylinders and write down the results for each cylinder. This is a "dry" compression test.

Squirt about 2 tablespoons of oil in the spark plug hole and immediately retest compression. Repeat for each cylinder and write down the results for each cylinder. This is a "wet" compression test. The oil helps the rings seal. Test results will naturally be higher during a wet compression test. If you notice one or more cylinders that are noticeably higher than the others, you have found a leaking ring. It could be a compression ring or an oil ring, the only way to know for sure is through disassembly.

A cylinder leakage test involves applying compressed air to each cylinder through a fitting inserted into each spark plug hole individually. A gauge is connected and leakage is shown in percentage.

It is the EGR valve causing it.

Replace your EGR valve.

It is the EGR valve causing it. Replace your EGR valve.

Why do you say this? Causing the oil in the filter, or causing the rough idle?

The EGR valve can cause a rough idle, and/or stalling, if it is not closing completely. The other symptoms you are experiencing, along with no "Service Engine Soon" light, do not indicate a problem with EGR. It is not possible for the EGR valve to allow oil into the air cleaner. The EGR valve controls exhaust gas only. It recirculates it into the intake manifold below the throttle body. The EGR valve is in no way connected to any oil source. The ONLY way for oil to accumulate in the air cleaner is when blow-by gasses are greater than the PCV system can handle. It may be due to the PCV system not operating efficiently, or there is excessive blow-by.

Is it smoking ? Sounds like excessive blow-by..

Ended up not doing the compression checks. But I did replace the EGR valve. Didn't help, but left the new one on anyway. I think it's a intake manifold vacuum leak causing the rough idle. I noticed this when I my cruise control started to act badly again. How can I find information out on a casting number for an intake manifold? I found one on Ebay for $80 and it's been cleaned and blasted. It's casting number is 14094011. The seller says it will fit my engine as long as I have the three bolt throttle body. I would like to be sure.

yep a high flow pump would be the cause - these 4.3's pull alot of vaccum thru the pcv on its own - and thus people have constructed catch cans to keep some of that oil from going into the engine - i believe this is the real source of why these motors suffer from carbon problems - perhaps taller valve covers are in order for these engines . the highflow pump will just aggrivate the problem by putting more oil in front of the pvc valve .

yep a high flow pump would be the cause - these 4.3's pull alot of vaccum thru the pcv on its own - and thus people have constructed catch cans to keep some of that oil from going into the engine - i believe this is the real source of why these motors suffer from carbon problems - perhaps taller valve covers are in order for these engines . the highflow pump will just aggrivate the problem by putting more oil in front of the pvc valve .


The original post was concerning oil in the PCV filter, air filter, and air cleaner. The only way possible for that to happen is by insufficient PCV flow or excessive blow-by. High volume or standard, an oil pump has nothing to do with blow-by. Blow-by is the result of a piston rings inability to seal combustion gasses away from the crankcase, and crankcase oil away from the combustion chamber.

The purpose of the "catch can" is to collect oil vapor from blow-by, contain it, and allow it to condense. The liquid can then be emptied and disposed of. Why not allow the PCV system to do what it was designed to do? Repair the root cause; don’t put a “band-aid” on the symptom.

Why not allow the PCV system to do what it was designed to do? Repair the root cause; don’t put a “band-aid” on the symptom.

Because right now a "band-aid" suits my budget better than a correct full repair. I'm looking forward for the future to purchase a small block for my Blazer.