PCV blowby question

[amkfken]

Sort of a long post, could be in Question and answer or a poll question, here goes..
Have put on 800 miles on the 83 SX/4 this summer checking out everthing.
Computer removed, everything but cat removed from emissions stuff.
Ignition upgrade, carb rebuilt, auto trans filter changed (never seen one so dirty!), shift linkage set, remaining vacuum hoses replaced.

Car runs great, 20+ mpg, plenty of power!!
First trip @ 40 mi @ 60+mph--  ok
Second trip@ 120 mi, some city driving-- tiny amount of oil in air cleaner housing.
Third trip @ 140 mi @60+ mph---oil dripping from front of air cleaner housing on pwrsteering.
Fourth trip @ 120 mi, some city driving, put a new air intake hose on housing as car had none when I got it.---Lost 1 qt+ oil all over
suspension left side, poured 1/2 pint out of air cleaner housing.

New pcv valve, clean filter in valve cover vent when this all happened.
Plenty of vacuum on pcv valve at idle and steady throttle--however--
I live at 9800+ ft elevation, must cross 2 10K passes to go anywhere, car runs great on the passes, however there is NO vacuum (or very little) at WOT on 6% grades, therefore PCV is shut down and reverses flow back thru air filter, that's where the vacuum is, hence oil flow in housing---Right???
Seems to be a problem only at high rpm’s or hard pulls.

Researching this on various Jeep forums, seems to be a common problem on high mileage vehicles with the 258, first comment is rebuild engine!!
Some have responded with use a catch can for the oil drips and deal with it, some have responded with a new type of PCV valve that has constant vacuum in the crankcase and have good reviews on problem solved without an engine rebuild.
SX/4 has 101k miles on it.

Here is the website, check it out and comment or maybe someone has already used this product.

http://www.envalve.com/

[ericarmstrong]

Are you sure you don't have other leaks besides the air cleaner? 1 quart seems very high to be lost through the air-in on the pcv. 
The oil is forced into the air cleaner not because of a new source of vaccum but rather by crankcase pressure, and a lack of vac from the pcv.  I would assume that having enough crankcase pressure to cause oil to pour out of your air cleaner is an indication of a larger issue.  Do you still have the meshy filter thing in the air cleaner at the pcv fresh air hose?

As far as the different pcv valve..... The evo valve is still a vacuum actuated valve, and even with a bigger hole I don't think it can compensate for that kind of oil loss.  If your getting oil litterally pouring out of the cover, a bigger pcv valve will just suck it up and have it burning in the cylinders.

I have no experience with  high altitude cars, so possibly this is a totally different ball game and my responce is null.
good luck! 

[amkfken]

There were NO other leaks (after replacing valve cover, still not leaking). This car is pristine, no rust or oil leaks anywhere (till now)!

Aircleaner filter is whole and clean, no smoke comes out of the vent at idle or when revving up, can't say what happens under load.
There is NO tailpipe smoke going down the passes, then accelerating, engine runs so quiet I have to check the warning red lites on the instrument panel to see if it's still running (no tach).

Will give the forum another week for comments/suggestions, my son (an ASE mechanic) suggested the old style road draft tube, he is stumped!

[ericarmstrong]

I would do a compression test. At the least take it on the high pass, get it to were it is expelling oil, and then pull out the pcv and look for smoke. 

[txjeeptx]

You may have good compression and a decent engine, but high gears(typical of Eagles)combined with stock or slightly oversized tires, combined with hills or a headwind can result in periods of time where the engine is working hard enough to have no effective crankcase ventilation, and pressure builds from normal, not excessive, blowby . . and oil gets forced into the air cleaner. A custom separator chamber or a change of axle ratio or reduction of tire diameter(without airing down), or properly inflating tires to reduce rolling resistance, can be the cures you're looking at. These engines didn't make much hp, and they were geared for a time when 55mph was THE limit, so keeping up with today's traffic means they're having to strain a bit. You can install a vacuum gauge inside the car and make sure you don't drive for too long with less than 5 "Hg vacuum.

I blew the valvecover clean off an AMC 4 cylinder in a YJ Wrangler by running it flat out floored for too long(big tires, tall gears, brick in the wind). Sudden smokescreen behind me prompted a quick exit from the hwy. It had been using oil by pushing it into the air filter housing. The cracked plastic cover couldn't take the pressure built up from having no manifold vacuum for so long(floored, overworked engine).

[amkfken]

Thanks  txjeeptx, you are kind of confirming my suspicions of low (or very little) vacuum at altitude, No wonder I don't see any eagles in the high country!!

At  idle engine only pulls 12"hg steady, inquiry on this board as to this relativley low number (as opposed to the 17-19 average out in the flatlands) indicates that my lower vacuum number is ok for this altitude.

I guess I can go anywhere in this country, just don't attempt to come back home!!

Was going to take the SX/4 to Kerrville TX next week to a Kaiser-Frazer convention, but with inoprative A/C, no way!!!

[txjeeptx]

Kaiser Frazer convention? Kerrville, TX? I'm searchin fer that one now.

Man, I can't go, got a wedding to go to.

[vangremlin]

At  idle engine only pulls 12"hg steady, inquiry on this board as to this relativley low number (as opposed to the 17-19 average out in the flatlands) indicates that my lower vacuum number is ok for this altitude.

Yea, I was told 14" hg is typical for Denver, so high country would be even lower!

[amkfken]

txjeeptx----The convention is the 20th to the 25th,  all cars etc. will be there on the 23rd and 24th.

Try to make it!!!

Cant be at a wedding all week!!

[ammachine390]

I have a similar problem on my Concord. At idle, it puffs blowby into the air cleaner box.  When I drive on the highway at higher RPMs, there is some oil inside the air cleaner box.  I live just outside of Chicago, so I'm not at high altitude, and the pcv seems to have good vacuum, however I don't have a vacuum gauge so I don't know an exact reading.  The main problem is, since its constantly pumping blowby into the intake, the air filters get dirty SUPER fast. I can't even drive 1000 miles and there all oily. The car only has 120,000 miles on it and it runs really good, (just gets bad mpg), any ideas? Or does this seem to be the norm?

[IowaEagle]

What is the mpg?   My Concord is not great either, 17 -18 mpg; but no blowby.

[ammachine390]

What is the mpg?   My Concord is not great either, 17 -18 mpg; but no blowby.

In town I get around 13, took it out on the highway a little (guessing about 40% highway, 60% in town), and am guestimating to get around 17 but I have yet to fill up to find out.  I guess I should probably do a compression test.  At idle, do you have vacuum at the pcv fresh air inlet hose? If so, do you know how much? On mine, I have pressure.

[IowaEagle]

I am not sure. I would have to check.

[txjeeptx]

If there is visible blowby going into the air cleaner at idle, like smoke coming out of the hose that leads to the air cleaner from the valvecover, then the engine's rings are worn out or one cylinder has a broken ring, because the hose leading from the valvecover the the air filter can is supposed to be a fresh filtered air intake for the PCV system. The PCV draws gasses out of the engine, and they go directly into the intake manifold to be burned off inside the engine, thus reducing the engine's overall emissions by capturing blowby that would have been vented to the atmosphere in the days before the PCV, and burning those gasses, thus running them through the catalytic converter. If blowby is more than the PCV can keep up with, especially at idle, when the vacuum available is greatest, then its an indication that something is wrong with the piston rings. The engine probably needs rebuilt. A compression test will show which cylinder is leaking the most.

If you drive an engine at zero vacuum for too long it developes internal pressure because even good sealing rings do leak some. For mountainous area driving, a catch can on the valvecover fresh air inlet will help keep oil out of the air cleaner. You can also make the PCV valve sit in a catch container to reduce the amount of oil that it draws up. The old concept of "road draft" drawing out vapors is a myth, the long crankcase vent tubes of the old flathead engines were just meant to send the pressurized vapors of the crankcase down below the firewall so they wouldn't get up into the cab and make you sick while you were driving and actually moving. Being stuck in traffic back then would have really sucked, since the hot vapors being literally pumped out of the draft tube by the pressure of blowby would rise up and get into the cab. I added a PCV valve to my flathead's draft tube(cut off tube and inserted a rubber grommet).

[mudkicker715]

If it gats worse you can. Actually pump all oil out of the engine through blowby. A catch can could help recover that but still just biding time.