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.

[Jurjen]

I'm with txjeeptx.

I added a PCV valve to my flathead's draft tube(cut off tube and inserted a rubber grommet).

I find that a "refreshing" idea! Certainly worth testing it.

[milliard431]

AMC put a different vacuum advance on the Eagles sold in high altitude areas. I don't know how it was different though. Maybe you can get one of those?

[amkfken]

Update:
Spent $50 for the "new" PCV valve (only available on the famous auction site), problem solved, NO more oil in the air cleaner assembly or dripping out all over the floor or driveway when parked.

All emissions control crap removed, even the computer is on my workbench, everything disconnected, even the wires removed! There is no vent for fresh air to the valve cover (plugged)

Gas mileage now up to 25+ mpg, no leaks anywhere. Just turned 102k miles on the SX/4

Living in God's country where emissions are only found on livestock and my dog (and me)!!!

[IowaEagle]

$50 for an OE PCV Valve???  They range from $1.00 to $2.73 at Rock Auto for the 4.2.  Are we talking about some other valve/device?

[68AMXGOPAC]

I am wondering that too , or else he meant $5 ??I have the same issue with Money Pit II , just as he describes.My PCV works,good vaccumm it seems, maybe a bit much at times ?? Idles around 5- 10 , running gets up around close to 20 I think. ( have to double check on a run tomorrow) So every few days I now open up the air cleaner and wipe it out.It has the PCV to the intake and I took another hose from where the fancy chrome breather was blowing oil all over, abd ran it into the air cleaner.The car doesn't smoke at all, just blows oil,too much pressure under the valve cover.It works like that, so it gets ran as is.I was thinking of a catch can thing,inlet on top, outlet hose connection inch or so off the bottom, stuff it with media to capture the oil out of the vapors and let it settle.

[mudkicker715]

You -without thatelectri check thing correct before you go to manifold vac correct.

[vangremlin]

$50 for an OE PCV Valve???  They range from $1.00 to $2.73 at Rock Auto for the 4.2.  Are we talking about some other valve/device?

Check the link in the original post - its a PCV valve on steroids, sells for $48

[IowaEagle]

My apologies.  I must have missed the first part of this thread.  I will have to read more.

[autumnglen]

Update:
Spent $50 for the "new" PCV valve (only available on the famous auction site), problem solved, NO more oil in the air cleaner assembly or dripping out all over the floor or driveway when parked.

All emissions control crap removed, even the computer is on my workbench, everything disconnected, even the wires removed! There is no vent for fresh air to the valve cover (plugged)

Gas mileage now up to 25+ mpg, no leaks anywhere. Just turned 102k miles on the SX/4

Living in God's country where emissions are only found on livestock and my dog (and me)!!!

So keep us updated on how well this new PVC valve is working, also can you post some pictures of your engine, I'd like to see how you plugged the air inlet.
Rita

[IowaEagle]

What Rita, said.  I am interested in this for the Eagle.

[HawkenEagle]

I just read their site. I gotta get one for the AMC and Studebaker. The low and high RPM there's really no where for the pressure to go but out the oil filler cap and the breather tube. This looks like a solution which does what a modern PCV should have been designed to do.
 $47 worth not having to scrub the block and air cleaner all the time.

[amkfken]

Rita--and others interested:

This is called a envalve, go to their website on my first post which I did not get much response, usually "rebuild the engine"!!
$50 is much less and worth a try so I did it!
It replaces the oem pcv, made of some type of plastic, hooks up exactly as the oem in the valve cover and hose to carb.
The original "fresh air intake" hose is cut to about 1" and plugged with included tapered plug (be sure to use a hose clamp).
This was the last step in engine/emissions/ignition mods.
There are NO leaks anywhere,valve cover,air cleaner housing,rear main--nowhere!!!
@ 102k miles I am amused by the constant complaints about mileage, poor performance, etc. with the 258, I can break any speed limit in Colorado at high altitude and still get 25+ mpg, city and highway combined
This is with the STOCK BBD carb,all emissions removed @ 6000 to 11,000 ft altitude, I am well pleased with the 83 SX/4!!
This is NOT a Ferrari, just a fun little car, just happens to have 4wd!

[68AMXGOPAC]

Well , that's enough said for me, I am going to try one.I was thinking though,if the original is too small, why not just run a line direct without a PCV ???or "T" the breather into the line between the PCV and manifold?So both lines go into the manifold.

[maddog]

i find it funny how many people tell me i need a new car just because it's an AMC. that's when i tell them that the engine in my car is the same one used in the 90's jeep cherokee that they're driving just that theirs is fuel injected with a different head. oh and i've had eagle eyes up to 120mph.

[IowaEagle]

Make them feel really bad and tell them its the same engine as found in 1964 Ramblers.

[maddog]

no they might try killing me then.

[earth1]

Well you have peaked my interest with the Envalve product... I am both skeptical and curious,

Josh

[IowaEagle]

I saw one in use at the Meet in Omaha.  They appear to do what they say they will do.

[Jurjen]

I think the ENvalve will do the job.
The original PCV-valve has a little more capacity than the actual blow-by of a new(ish) engine.
This keeps the engine at a low vacuum.
Fresh air is taken in thru the rear hose from the airfilter housing.

When the engine is getting worn, there is more blow-by than the PCV-valve can evacuate.
The engine crankcase becomes pressurized and the excess vapours are now pushed out through the rear hose into the air filter housing.
The ENvalve is just a high capacity PCV valve and will take care of the extra blow-by gasses.
It will not repair worn piston rings, but it will compensate for it.

[jim]

An Egg to you, sir, for that explanation.

[HawkenEagle]

The Envalve could also save your engine from fuel dilution problems as it requires you block off the fresh air hose and keep the engine at a constant 3 to 4" of Mercury. Their own tests in the literature showed in the same engine the engine lubricant remained cleaner and oil analysis showed viscosity retention lasting longer. Severe blow-by will cause a motor oil to sheer out. This system evacuates these gasses at operating temperature and like Jurjen said - isn't a repair but rather helps you get along through its demise.

I should do a compression test but the lady at ENvalve said the 256 Jeep is her #1 customer base which leads me to question the design of the oil drains in the head.
Another situation may arise where not just more blow-by but flooding in the valve cover of oil and a slight amount of pressure will naturally push the oil through the fresh air hose into the air cleaner. Not with the Envalve! Instead this small amount of oil will be burned rather than pool up in the air cleaner or contaminate more oil in the cump.  I reciently saw a engine cleaner test where a Jeep 4.0 was used and it too had more carbon build-up than the same year toyota and cadillac used in the test. This shows the importance of regular intake cleaners.
 

[68AMXGOPAC]

Hawken, good point on dillution and flooding of oil in the valve cover.Both are blatently apparent in mine.This really is the first run of the Money Pit II , for any length of milage, as I don't think it got driven because of it's blow-by when Smitty had it.I had changed the oil after putting about 200 miles on it because it had sat so long without bieng used.It now has 2500 on the change and listening to the engine, and looking at the oil on the stick it needs it allready.I also noticed when at first trying to evaluate the oil issue , that it did push out the fresh air vent, and seemed to lay up in the head alot,never  had an issue like this before,bad rings would usually smoke like crazy , but this doesn't at all. I am getting one of these and trying it out,seems apparent it works by the testimonys.

[AMCKen]

I wonder what would happen if one just plugged the fresh air hose and used the regular PCV valve? Would the engine then start drawing air into the crankcase from where ever it was leaking? Could mean drawing dust and dirt into the crankcase rather than the filtered air from the air cleaner.

[ammachine390]

If you were to plug up the fresh air inlet, the blow by would not be able to escape during low manifold vacuum. So if you were flooring it long enough, or just loading the engine long enough, the pressure would build up, and you would blow a seal somewhere.

[craigp29690]

While replacing all the heater hoses, heater valve, t'stat and water pump I had to remove the air cleaner to get to the rear hose going to the heater valve.  I noticed a PCV at the rear of the valve cover piped to a connection above the base of the carb, not to the air cleaner.  There is a small Mr. Gasket air filter at the front of the valve cover.  The port on the air cleaner that I would asusme the PCV would be routed to is not connected to anything.

This setup is different than my 81 Concord so I don't have a "go-by".  Since I would assume the PCV should be connected to the air cleaner what would normally be connected to that large of a port on the carb?

Also discovered one other thing.  Before all this work the car sounded like it had an exhaust leak and when you first started it up you could actually see (and smell) a thin cloud of exhaust waft up in front of your face.  I figured a donut is gone or maybe a hole somewhere.  When putting things back together there are two large hoses that connect to the back of the air cleaner (part of emission control coming off the exhaust) one line was very loose, I clamped it, started the car to check out the repairs and exhaust noise and leakage into the car were gone.  It was as quet as a ninja.

[JayRamb]

I put it in an EN VALVE in my 84 Eagle with 245,000 miles and it runs like a TOP! I cannot believe how the vacuum increased and it gets better mileage and no blow by. I actually found the oil leak from my valve cover that I tightened down and the leaks stopped. AMAZING product. the En VALVE!  I bought one for my show car...87 Eagle.

[68AMXGOPAC]

The PCV does go to the carb base port.The other one used to go to the air cleaner but someone has just put a "breather" there in it's place.Mine used to have the breather also that someone installed, but blew too much oil residue out of it , so I put the original hose back to the air cleaner.It goes to a small square plastic piece held inside the air cleaner with a small mesh filter in it.

[ammachine390]

I put it in an EN VALVE in my 84 Eagle with 245,000 miles and it runs like a TOP! I cannot believe how the vacuum increased and it gets better mileage and no blow by. I actually found the oil leak from my valve cover that I tightened down and the leaks stopped. AMAZING product. the En VALVE!  I bought one for my show car...87 Eagle.

Did it used to pump oily mist/oil into the air cleaner? Did you just install a cap on the breather so that the crankcase actually holds the vacuum?

[JayRamb]

If you to www.envalve.com it will give you the information on how it works.

[ammachine390]

If you to www.envalve.com it will give you the information on how it works.

I've been on that website before, I understand the principle, but I don't see any instructions. Just wondering how bad your blowby was, and whether or not you capped the pcv inlet.

[JayRamb]

Let's see:
1. You take out the old PCV.
2. Replace that with En-Valve
3. Block/Cap off the inlet hose to the air-cleaner...no longer used
4. I was experiencing a quart of blow by every month. There was NO blue smoke ever in my tailpipe.

[ammachine390]

Let's see:
1. You take out the old PCV.
2. Replace that with En-Valve
3. Block/Cap off the inlet hose to the air-cleaner...no longer used
4. I was experiencing a quart of blow by every month. There was NO blue smoke ever in my tailpipe.

Thanks, exactly what I needed. But I still wonder, when the engine is run at high load condition when there is no vacuum, how does the blowby escape when the inlet is capped? Have you ever experienced any problems with the envalve? Has the cap or oil fill cap ever blown out? And lastly, how much did this increase your mpg?

[68AMXGOPAC]

I think you should allways have "some" vaccumm. Running at 65 - 70 mph for a length of time on the highway, I still see 5+ to 10 on the vaccumm gauge.