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Thread: Does WJ burns oil? Reply to Thread
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  Topic Review (Newest First)
07-24-2019 07:15 AM
2oldjeeps ok,tnx, will do
07-24-2019 12:28 AM
Fzz
Quote:
Originally Posted by 2oldjeeps View Post
how to get pcv valve out? without breaking...

i pulled the hose off air box,no vacume on box or hose?
The PCV valve in the oil filler neck turns slightly to 'un-click' from where it seats.
They are very cheap, so may as well get the replacement first, just in case the old one has gone brittle.

I'm pretty sure that the hose that goes to the airbox/intake box (4.7L V8 Power Tech etc) upstream of the throttle body, just connects to the valve covers (the PCV pipe goes to the back of the manifold).
So if the hoses are all ok and your engine doesn't have excess blow-by/knackered stem seals, there shouldn't be much pressure coming out of the valve cover hoses. If the engine's running tho there should be some vacuum into the airbox?
07-23-2019 09:46 PM
BilletHorse There is a known issue with the factory piston design. They placed the ring pack too close to the top of the piston which eventually leads to a burned ring land. The aftermarket pistons available have corrected this issue. They did it to eliminate the dead space above the top ring and below the piston top for emissions reasons, but it was ill-considered.
07-23-2019 03:09 PM
2oldjeeps how to get pcv valve out? without breaking...

i pulled the hose off air box,no vacume on box or hose?
07-23-2019 09:31 AM
Tek99
Quote:
Originally Posted by GmanWJ View Post
Responding to the original question ... I have a 4.7L with ~195,000 miles (~314,000 km) which uses probably 1 liter of oil every month. I changed valve cover gaskets, oil pan gaskets, and rear main seal hoping to stop the oil loss. It still uses oil, but not as much as it used too so the new gaskets helped. Check your oil dipstick regularly from now on and add oil as needed.


As for the rest of this thread ... Oh my god if my oil loss can be solved by cleaning a couple breather tubes, I am going to kiss all of you.


Interesting, mine has 320K km on it. For the past 2 years I have been changing oil every 7K km and I usually dumped around 5l of old oil so i assumed that was OK. But 2,5l liter of oil loss after 12K km that seems a little bit too much. Doesn't it?
07-22-2019 11:27 AM
GmanWJ Responding to the original question ... I have a 4.7L with ~195,000 miles (~314,000 km) which uses probably 1 liter of oil every month. I changed valve cover gaskets, oil pan gaskets, and rear main seal hoping to stop the oil loss. It still uses oil, but not as much as it used too so the new gaskets helped. Check your oil dipstick regularly from now on and add oil as needed.


As for the rest of this thread ... Oh my god if my oil loss can be solved by cleaning a couple breather tubes, I am going to kiss all of you.
07-16-2019 05:53 AM
Fzz
Quote:
Originally Posted by schwim View Post
Thanks for the replies, guys. Am I right that I just need to pull that T-shaped hose system off, ensure it's free of blockages and then find the PCV valve and make sure it rattles? Or have I misunderstood the instruction?
The T-shaped hose system connects both valve covers with the intake upstream of the throttle body etc (where your hose was disconnected).

From memory I think the PCV connects to the rear of the inlet manifold - If that's right the valve covers and PCV are on different 'circuits' so different things to check.
07-15-2019 04:59 PM
schwim Thanks for the replies, guys. Am I right that I just need to pull that T-shaped hose system off, ensure it's free of blockages and then find the PCV valve and make sure it rattles? Or have I misunderstood the instruction?
07-15-2019 04:09 PM
Fzz [QUOTE=schwim;40679413]Could you guys give me a hint on where these two pipes are on the intake? I looked at the breather box where the filter resides and I didn't see any pipes attaching to it. I looked behind the intake box on top of the engine and I see 1 pipe entering on the side(that was disconnected on my engine) and a few attaching around the back towards the firewall. Are any of these what you're talking about?




If that pipe was disconnected when you found it, there probably should have been a bit more oil mist on the surrounding components, as the vapours would've been pouring out into the engine bay rather than going into the intake - might indicate a blockage or dodgy pcv upstream?
07-15-2019 01:34 PM
CarlJH the first picture is the breather pipe, follow it to the back and you should find something like the picture.
second pic are the evap pipes for the charcoal canister/fuel tank vapor recovery
third picture are brake booster, cruise control and evap pipe vacuum supply.
07-15-2019 10:38 AM
schwim Could you guys give me a hint on where these two pipes are on the intake? I looked at the breather box where the filter resides and I didn't see any pipes attaching to it. I looked behind the intake box on top of the engine and I see 1 pipe entering on the side(that was disconnected on my engine) and a few attaching around the back towards the firewall. Are any of these what you're talking about?








07-14-2019 02:31 PM
Fzz
Quote:
Originally Posted by CarlJH View Post
there are 2 breather systems on the 4.7,
the 2 breathers from the back of the cylinder heads are connected in front of the throttle body so just allow a filtered metered amount of air in to the cam covers at the back of the engine. that filtered air plus any blow by gases is then drawn into the engine via the check valve on the filler neck.
you should be able to hear the valve rattle when you take it off and shake it.
I've just done the cam cover gaskets and found the breathers full of mayo, the heads themselves where nice and clean, so took them apart and cleaned them out with brake clean and compressed air.
+1
On my first 4.7 WJ the breather valve on the filler neck was kaput - but the pressure build up it was causing forced oil out of the main seals. I dreaded doing those seals, but the leaks went when I fitted a new breather valve, which was nice. In winter I made sure to clean it out regularly too as CarlJH says they are prone to condensation/mayo at that point.
07-14-2019 01:37 PM
CarlJH there are 2 breather systems on the 4.7,
the 2 breathers from the back of the cylinder heads are connected in front of the throttle body so just allow a filtered metered amount of air in to the cam covers at the back of the engine. that filtered air plus any blow by gases is then drawn into the engine via the check valve on the filler neck.
you should be able to hear the valve rattle when you take it off and shake it.
I've just done the cam cover gaskets and found the breathers full of mayo, the heads themselves where nice and clean, so took them apart and cleaned them out with brake clean and compressed air.
07-14-2019 12:51 PM
schwim
Quote:
Originally Posted by CarlJH View Post
you should check the breather pipes as they can get blocked very easily and will cause more crank case pressure, which will force the oil past the piston rings more than it should.
the ones that get blocked are the 2 right at the back of the cylinder heads and go to the right side of the air box looking from the front of the car.

My 4.7 burns a lot of oil and this is the first I've heard of this! I know better than to hope this gets rid of all of the disappearing act that the oil is doing but I really do hope that it's the cause of some of the issue.
07-13-2019 11:08 AM
CarlJH Hey your English is a lot better than my polish!
you should check the breather pipes as they can get blocked very easily and will cause more crank case pressure, which will force the oil past the piston rings more than it should.
the ones that get blocked are the 2 right at the back of the cylinder heads and go to the right side of the air box looking from the front of the car.
also check the cam covers at rear bottom corners for any leaks, If the gaskets have never been changed they will be hard and brittle by now.
I don't think you would have damaged the motor with low oil, as long as the end of the pick up tube was in the oil it would be fine. If it had lost oil pressure it would started chiming at you and the "check gauges" warning lamp would have come on.
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