Yes...Another PCV/CCV thread :)

[Piilgrim82]

Hi everyone!

 

I've been the proud owner of a 1990 MJ Pioneer with the 4.0 engine for about almost 2 years now. Don't have a lot of mechanical know-how, but a huge desire to learn -for which this site has been a huge resource. Anyway, I'll start off by saying that before starting a thread I took time to look through a large number of other threads about PCV/CCV questions, and after reading quite a few I still have some questions. One of my next purchases will be a good shop manual, but I'm in a small town in northern Canada so I don't want to wait a few weeks for that...anyway, here goes:

 

I need to replace the front PCV/CCV valve and hose. I had removed the one end of the hose from the air box and routed that end of it below the engine because I was tired of my air filter getting full of oil. However, I was also having issues with the PCV valve popping out of the valve cover. When I was flushing my coolant system the other day, I realized the valve and hose were completely gone -it must have popped out at some point in the last couple weeks and fallen out completely along with the hose! Haha. Reading the forums the last couple days, I now realize that the front valve us supposed to be the intake valve, and the rear is the escape valve -so the front valve popping out and the oil in the filter means that my system was clogged and not working properly (but you guys already knew that haha).

 

All that being explained, I want to replace both the front and rear PCV/CCV valves and hoses properly. However, reading this thread made me wonder if the way the hoses were when I bought the truck was correct: 

 

 

Secondly, in the other threads I've read such as the one linked above and this one: 

Everyone is saying that the front valve is not a PCV, but rather a CCV and that the valve is just an elbow. As you can see in the picture above, my valve was not just an elbow, it was a small valve with a metal lower sleeve that simply fit into the rubber grommet...which again raises my question as to whether this system was set up properly on my truck when I bought it. And if anyone has a links to the parts I need to order, that's the ultimate goal here.

 

And if you've had the patience to read all this, thanks in advance for your help! Just a rookie trying to educate himself!!!

 

[MiNi Beast]

Yes. Replace valve cover.

 

 

Side note, i ran my hose into a 20oz soda bottle to catch oil and just dumped it back in when filled up. I'm just a redneck though. Turned out i had a burnt up valve though. 

[Cali Cruse]

Hi everyone!
 
I've been the proud owner of a 1990 MJ Pioneer with the 4.0 engine for about almost 2 years now. Don't have a lot of mechanical know-how, but a huge desire to learn -for which this site has been a huge resource. Anyway, I'll start off by saying that before starting a thread I took time to look through a large number of other threads about PCV/CCV questions, and after reading quite a few I still have some questions. One of my next purchases will be a good shop manual, but I'm in a small town in northern Canada so I don't want to wait a few weeks for that...anyway, here goes:
 
I need to replace the front PCV/CCV valve and hose. I had removed the one end of the hose from the air box and routed that end of it below the engine because I was tired of my air filter getting full of oil. However, I was also having issues with the PCV valve popping out of the valve cover. When I was flushing my coolant system the other day, I realized the valve and hose were completely gone -it must have popped out at some point in the last couple weeks and fallen out completely along with the hose! Haha. Reading the forums the last couple days, I now realize that the front valve us supposed to be the intake valve, and the rear is the escape valve -so the front valve popping out and the oil in the filter means that my system was clogged and not working properly (but you guys already knew that haha).
 
All that being explained, I want to replace both the front and rear PCV/CCV valves and hoses properly. However, reading this thread made me wonder if the way the hoses were when I bought the truck correct: 
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Secondly, in the other threads I've read such as the one linked above and this one: 
Everyone is saying that the front valve is not a PCV, but rather a CCV and that the valve is just an elbow. As you can see in the picture above, my valve was not just an elbow, it was a small valve with a metal lower sleeve that simply fit into the rubber grommet...which again raises my question as to whether this system was set up properly on my truck when I bought it.
 
And if you've had the patience to read all this, thanks in advance for your help! Just a rookie trying to educate himself!!!
 

I have no advice, but a compliment on your Canadian politeness! I have exactly same issue with my Comanche. Oil in the air filter.

Sent from my SM-G935T using Tapatalk

[Piilgrim82]

4 hours ago, MiNi Beast said:

Yes. Replace valve cover.

 

 

Side note, i ran my hose into a 20oz soda bottle to catch oil and just dumped it back in when filled up. I'm just a redneck though. Turned out i had a burnt up valve though. 

Yes to what part of it exactly? That my system was not set up right or that the system was obviously clogged?

 

Thanks for the reply!

[MiNi Beast]

Clogged and looks setup properly. But the said valve is in the cover in the rear. Blow by they call it. But some replace to a newer valve cover with good results. Not much for details sorry. 

[Piilgrim82]

34 minutes ago, MiNi Beast said:

Clogged and looks setup properly. But the said valve is in the cover in the rear. Blow by they call it. But some replace to a newer valve cover with good results. Not much for details sorry. 

All good! Makes sense now. Thanks again!

 

And something I should've mentioned earlier is that I was skeptical that my system is routed properly, because in the first thread I mentioned above they list these as the correct parts for the front valve, which appear to route the hose through the vacuum harness?? https://www.rockauto.com/en/moreinfo.php?pk=586584&cc=1181720&jsn=390 and https://www.rockauto.com/en/moreinfo.php?pk=586585&cc=1181720&jsn=391

[Wounded_Fighter]

Autozone part numbers in images. (46003 and 46005)

Contains all hoses, newer valves and grommets.

 

They were a Beast to push the grommets in... get a pick to assist.

 

 

[Piilgrim82]

Thanks Wounded_Fighter! Exactly what I needed. After googling engine bay pics it looked like the line should go to the vacuum harness, so you helped confirm that too! 

 

Also, looks like you decided to cut off the end of the breather tubes on the inside of the valve cover...been hearing good things about that so I think I'll do the same!

[Wounded_Fighter]

3 minutes ago, Piilgrim82 said:

Thanks Wounded_Fighter! Exactly what I needed. After googling engine bay pics it looked like the line should go to the vacuum harness, so you helped confirm that too! 

 

Also, looks like you decided to cut off the end of the breather tubes on the inside of the valve cover...been hearing good things about that so I think I'll do the same!

Also helps with clearance for upgrade to rockers. So I'm told. Will find out in the near future. 

[cruiser54]

CRUISER'S MOSTLY RENIX TIPS

CRUISER’S VALVE COVER MOD

NOVEMBER 17, 2015 SALAD 44 COMMENTS

Most early and even later Renix 4.0s could be bothered by excessive oil in the air cleaner box.

A fix from my old days as Service Manager at a Jeep dealership follows. Information was provided to me from a buddy at JeepTech during those days. I don’t believe it ever came out in a Technical Service Bulletin.

Remove the valve cover and turn it over. Next, remove the fluted tubes that are now facing you by removing three screws on each.

Chop 1 inch off each of them. Then, drill a half inch hole as shown in the photo. The flat side of the flute that’s closest to the edge of the valve cover. 

 

Clean and de-burr/sand all rough edges nicely, clean with solvent, and reinstall. Don’t be concerned about the chintzy gaskets that will probably crumble into oblivion when you remove the fluted tubes. They can go back together without gaskets.

Here’s a handy video from my friend Brendan showing more detail.

[cruiser54]

CRUISER'S MOSTLY RENIX TIPS

RENIX VACUUM HARNESSES

NOVEMBER 17, 2015 SALAD 19 COMMENTS

 

The vacuum harness that attaches to the front of the valve cover and includes the grommet/fitting, and is called the front harness, is Napa part number BK 715-1367 or is a Dorman 46003.

The vacuum harness that is closest to the air cleaner, EGR etc, and is called the rear harness, is Napa part number BK 715-1366 or is a Dorman 46004.

The tube from the rear of the valve cover to the intake manifold is part number BK 715-1365 or Dorman 46005 and comes with the valve cover grommet.

The Throttle Body to MAP hose is no longer available. Click HERE to access a fix for that.

[Eagle]

On 4/12/2020 at 5:14 PM, Piilgrim82 said:

I need to replace the front PCV/CCV valve and hose. I had removed the one end of the hose from the air box and routed that end of it below the engine because I was tired of my air filter getting full of oil. However, I was also having issues with the PCV valve popping out of the valve cover. When I was flushing my coolant system the other day, I realized the valve and hose were completely gone -it must have popped out at some point in the last couple weeks and fallen out completely along with the hose! Haha. Reading the forums the last couple days, I now realize that the front valve us supposed to be the intake valve, and the rear is the escape valve -so the front valve popping out and the oil in the filter means that my system was clogged and not working properly (but you guys already knew that haha).

 

 

Point of clarification: Your 4.0L engine does not have a PCV valve. PCV is an acronym for "Positive Crankcase Ventilation" -- the 2.5L engine has a PCV valve. The 4.0L system does not have any valve -- the flow is supposed to be controlled/regulated by the size of the rear (suction) tube. That's the one that gets clogged. There is no valve -- not in the front, not in the rear.

 

In the old days, before emissions became a thing, engines just had an open tube out one side that turned down and vented to the atmosphere. That worked, but as the engines aged and developed more blowby, they pushed more and more oil out those tubes. Once we got into controlling emissions, the engineers decided to capture those oily fumes and recycle them through the engine to burn them. So -- no more dump tube in the side of the block.

 

So now the inside of the engine was essentially sealed. But blowby still happens, so there has to be somewhere for those fumes to go. So they put a fresh air inlet in one end of the valve cover, and a suction tube in the other end. The suction tube led to the carburetor, throttle body, or direct to the intake manifold. Engine vacuum then pulled air out of the engine through the suction tube, and it was replaced by fresh air coming in through the inlet -- or by blowby. Unless an engine gets really bad, the system should suck out more than blowby  puts in. The crankcase is under negative pressure.

 

If the suction tube gets clogged -- which is what happens to the 4.0Ls -- there is no suction (or it's greatly reduced). When that happens, blowby pressurizes the crankcase. That pressure, which has oily fumes in it, has to go somewhere. I can't get through the skinny tube where it's supposed to go, so it goes out the other opening -- the opening that's supposed to be the inlet. That's when we get oil dripping into the air box.

 

Rerouting the inlet hose to a catch can is essentially just reverting to the old, pre-emissions control system of leaving the crankcase open to the atmosphere. In theory (although it wouldn't be legal, but neither is the catch can) you could just put on a longer hose, run it down to the frame rail, and let it drip onto the ground while you drive.

[WahooSteeler]

Eagle, thanks for that detailed and simplified explanation, best one I've ever read of not only how blow-by occurs but why. I have learned something today.  

[Piilgrim82]

Thanks a million cruiser54, that's exactly what I needed!!!

 

Huge thanks to Eagle too, because now I understand why I need those parts (and know the answer to the argument regarding whether its a PCV or CCV ;)!!

 

Keep up the good work fellas.

[CornFed]

Question for yall I order a pcv valve for my 2.5l figuring it took one. However it has a similar design as the 4.0 I'd post a picture but I've tore it apart so I can go in the morning and order parts. My question is why do I have that setup with the ccv lines instead of the pcv valve that the part store says the truck should take?