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Unread 02-26-2011, 11:29 PM   #1
Rynfw100
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93 YJ 2.5L Oil Blowback Problem

Hi, this is my first post, although I've been reading everything I can religiously, trying to learn as much as possible about my Jeep, and what-not.

Since this is my first post, I must say that my Jeep is a beast. I've had it for about a year, and it's pretty much stock everything, except the rims and sound system. It has taken me up steep hills with loose rocks, rolling with 235/75/R15. Never broke down on me, failed to start up, and has even put up with me as a driver.

Now, onto the problem at hand. When I bought the Jeep, the owner pointed out Oil on the Firewall, Valve Covers, whatever was in the area. My Father, being the old mechanic, told me that this wasn't much of a problem, probably a Valve cover leak/Oil Cap Leak. After multiple tests (Vacuum Leaks, Breather System Blocks, etc) we discovered oil in the Air Filter System, and a Crack in the Breather Tube. We fixed the breather tube, and removed the oil on the Valve Cover, Firewall, and whatever Gravity may have gotten dirty problem. However we could not find out what was causing the engine to put oil into the air filter. Well, with much research, and money spent, Experts say that it is a Piston Ring Leak/Blow by, which we all know is a pain when trying to fix it.

However, Another one of my mechanically adept buddies recently informed me that this issue is usually caused by a Valve Ring Leak, and went on (in annoying detail ) that the piston doesn't touch oil, and wouldn't cause oil to be pushed from the valves up through the breather system, into the filter.

So here I am, trying to make this Jeep completely mechanically sound, and a reliable Daily Driver, however two completely different scenarios, one being harder (and cheaper) than the other make this hard to figure out. I'm wonder what I should do in order to fix this problem. My father wants me to get the Block completely refurbished, bored, fixed, rebuilt if I'm going to rebuild the engine to fix the Problem. Since we do not have the tools to machine the engine, only a shop can do it. After doing some looking around, the cheapest shop will Rebuild the lower half of my engine (New parts, Camshafts, Rods, etc) for a hefty $1300 dollars. Well, considering the cost, and just recently graduating high-school, this doesn't seem easily done. However, I did buy a engine off CL from an XJ, that I could refurbish, instead of having to jerk my engine and not have anything to drive. The Second solution just Rebuilding/Buy New Heads for $120-300.

Any Ideas on what the problem actually is? The engine runs absolutely fine, no stutters, easy to start, Horrible on Gas , Doesn't miss... just blows all the oil everywhere. If you need further information, just ask a question, or if you need pictures, just ask for them as I appreciate any help... especially if it results in being easier on the wallet (Currently make about 800-1000 bucks a month). Thanks for Reading, and sorry for making it soo long, just wanted to get as much information down as I could.


Last edited by Rynfw100; 02-26-2011 at 11:53 PM.. Reason: Willingness to take pictures to help
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Unread 02-27-2011, 12:42 AM   #2
moonshinefuel
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Is it burning oil out of the exhaust? Or is this just oiling up your intake? Right now you are making decisions in terms of speculation, not tests, and more evaluation. How do the spark plugs look? Oil fouled? At least 1 or more? Have you done a wet/dry compression test? What are the readings? How many miles on the engine? There may be other reasons you are overlooking that are causitive factors other than piston rings or a valve seal problem. You are mentioning the engine runs perfectly fine but just blows oil everywhere.. Where? In the engine comparment? Or out the exhaust? Or both? Pull all of your spark plugs, how do they look?
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Unread 02-27-2011, 12:53 AM   #3
GEARHED
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Not sure if it helps without a picture (too dark outside to take one) but had a conversation with another gearhead the other day about this very thing. When he got his first Jeep he didn't know it had an oil sensor and if you don't replace it, you get what you are describing.

Its just one of those things I'd have to take a picture of and circle so you know what I'm referring to - us old folks don't keep up with new part lingo.
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Unread 02-27-2011, 02:51 AM   #4
Mud-n-Beer
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Quote:
Originally Posted by Rynfw100 View Post
Hi, this is my first post, although I've been reading everything I can religiously, trying to learn as much as possible about my Jeep, and what-not.

Since this is my first post, I must say that my Jeep is a beast. I've had it for about a year, and it's pretty much stock everything, except the rims and sound system. It has taken me up steep hills with loose rocks, rolling with 235/75/R15. Never broke down on me, failed to start up, and has even put up with me as a driver.

Now, onto the problem at hand. When I bought the Jeep, the owner pointed out Oil on the Firewall, Valve Covers, whatever was in the area. My Father, being the old mechanic, told me that this wasn't much of a problem, probably a Valve cover leak/Oil Cap Leak. After multiple tests (Vacuum Leaks, Breather System Blocks, etc) we discovered oil in the Air Filter System, and a Crack in the Breather Tube. We fixed the breather tube, and removed the oil on the Valve Cover, Firewall, and whatever Gravity may have gotten dirty problem. However we could not find out what was causing the engine to put oil into the air filter. Well, with much research, and money spent, Experts say that it is a Piston Ring Leak/Blow by, which we all know is a pain when trying to fix it.

However, Another one of my mechanically adept buddies recently informed me that this issue is usually caused by a Valve Ring Leak, and went on (in annoying detail ) that the piston doesn't touch oil, and wouldn't cause oil to be pushed from the valves up through the breather system, into the filter.

So here I am, trying to make this Jeep completely mechanically sound, and a reliable Daily Driver, however two completely different scenarios, one being harder (and cheaper) than the other make this hard to figure out. I'm wonder what I should do in order to fix this problem. My father wants me to get the Block completely refurbished, bored, fixed, rebuilt if I'm going to rebuild the engine to fix the Problem. Since we do not have the tools to machine the engine, only a shop can do it. After doing some looking around, the cheapest shop will Rebuild the lower half of my engine (New parts, Camshafts, Rods, etc) for a hefty $1300 dollars. Well, considering the cost, and just recently graduating high-school, this doesn't seem easily done. However, I did buy a engine off CL from an XJ, that I could refurbish, instead of having to jerk my engine and not have anything to drive. The Second solution just Rebuilding/Buy New Heads for $120-300.

Any Ideas on what the problem actually is? The engine runs absolutely fine, no stutters, easy to start, Horrible on Gas , Doesn't miss... just blows all the oil everywhere. If you need further information, just ask a question, or if you need pictures, just ask for them as I appreciate any help... especially if it results in being easier on the wallet (Currently make about 800-1000 bucks a month). Thanks for Reading, and sorry for making it soo long, just wanted to get as much information down as I could.
This is a very common problem with Jeeps. I have the same problem that you are talking about. Just bad workmanship in the design / workmanship on these engines.

If you really want to keep your Jeep, I'd go with a remanufactered Jasper engine. Lots of money to put out on another engine, but better than the junk factory engine.

The blow-by is not that bad in my engine, but it is still there. My engine runs great, with plenty of pulling power. From the line that goes to my air filter assembly, from the rear valve cover, I put a tee fitting there, with some fuel line / vacume line that goes to the corner of the firewall / between the charcoal canister, i keep a soda bottle than gets most of the oil, if any, as my engine does not have much blow-by. Some of the oil still gets into the air filter assembly, but no where as bad as it did before.

I bought one of those 4" air filter assemblys that Pepboys, Autozone sells so I would not get any oil in my air filter, and just rotate the original air filter top to the back. Still run the hose to the bottle in the corner.
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Unread 02-27-2011, 06:29 AM   #5
kelti819
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I also had this problem. Turned out to be the other breather on the valve cover was clogged. On my 92 2.5 the breather was on the drivers side of the valve cover. Just a small threaded in nipple that has a vacc line that leads back to the intake right under the throttle body. I unscrewed it and took one of my wifes hair pins (bobby pin) and some brake cleaner and scrapped and cleaned it. Put it back together and problem was solved. I was loosing about 2 qts every 500 miles or so and now i dont lose any.
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Unread 02-27-2011, 06:51 AM   #6
CJ51973
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I had an old Suburu in High school that had a lot of blow by. I took a mason jar, brased two copper 90s to the lid and put it in the line between the valve cover and the breather. The oil would settle in the jar, not the breather. And I could unscrew the jar and pour the oil back in the motor. Worked for 25K until I traded it. You could do the same thing with a big fuel filter. Something that allows pressure drop.
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Unread 02-27-2011, 07:10 AM   #7
natedawg3256
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Mine was also a clogged hose the one on the front of the valve cover.cleaned it out no problems since
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Unread 02-27-2011, 07:27 AM   #8
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Some ppl find that by taking the valve cover off and cleaning the bejesus out of it including the baffles helps with the problem. Just make sure that all of the hoses are clear and there are no leaks in the ccv system.

Dwayne
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Unread 02-27-2011, 01:16 PM   #9
Rynfw100
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Quote:
Originally Posted by moonshinefuel View Post
Is it burning oil out of the exhaust? Or is this just oiling up your intake? Right now you are making decisions in terms of speculation, not tests, and more evaluation. How do the spark plugs look? Oil fouled? At least 1 or more? Have you done a wet/dry compression test? What are the readings? How many miles on the engine? There may be other reasons you are overlooking that are causitive factors other than piston rings or a valve seal problem. You are mentioning the engine runs perfectly fine but just blows oil everywhere.. Where? In the engine comparment? Or out the exhaust? Or both? Pull all of your spark plugs, how do they look?
This is what I like, Firm Pressure, I will answer as many questions now, and I will find the answers to the others.

It is not burning oil out of the exhaust, I do not believe. We have checked the plugs, and they seemed quite alright. We haven't done a Wet Compression test, wouldn't know how to start this... have done a dry, was within normal range. My Jeep has 140500 Miles on it. The Engine does run fine, no skipped cylinders, the oil just blows into the Air Filter Box, which in turn leaks from the box onto my engine compartment down to the suspension.

I will check my plugs, refer to my plug guide, and I will get back to you on that.

How does one go about doing a "wet" compression test?


EDIT: I checked the Vacuum Plug on the Side of the Vacuum Cover, you could see right through it... no need to clean. Plugs are also fine.

Last edited by Rynfw100; 02-27-2011 at 03:02 PM..
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Unread 02-27-2011, 07:44 PM   #10
josbtlr
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mine was doing that it was just the vaccum lines were off or on wrong to the carb got them all figured out and it stopped
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Unread 03-02-2011, 08:24 AM   #11
Rynfw100
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Nobody has any other tests that might indicate other problems? I mean I can clean the bajeezus out of the Valve Cover, but I do not think that is the problem. Just Ask

I'm also considering a 4.0L AX15 Swap. If you don't consider the Engine, Transmission, PCM/ECU, and Wiring harness into the mix... how much would it cost to do that drive train swap, buying longer/shorts drive shafts, radiators, etc?
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Unread 03-02-2011, 09:19 AM   #12
Que89YJ
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You can get a catch can like we put on the turbo when you go positive on crank case pressure. It will work like the jar previously mentioned. On to the engine discussion. You have a Jeep that has 140,000 on it and is driving fine. All your indications are the motor is running great. You are on a limited budget. Why are you doing anything to it but normal maintenance? The fact that you are on limited funds means the longer you strech your current motor the better off you are. Bank some cash while you are driving it and when you have the $$$$ to do it right get the Jasper long block. The blow by is normal and unless it is giving you indication of emminent mechanical failure you are likely to get another 30-40,000 miles out of it.
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Unread 03-02-2011, 01:22 PM   #13
cthames
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I had the same problem. this past weekend I took off the valve cover and found my baffles all clogged up. Cleaned up and replaced with new casket and new air filter and have seemed to solve the problem!
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Unread 03-02-2011, 03:31 PM   #14
hesserdude07
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i had the same problem when i bought my jeep. I changed my head gasket, and also cleaned out my baffles in my valve cover and have not had a problem in 2 yrs.
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Unread 03-02-2011, 11:33 PM   #15
Rynfw100
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Quote:
Originally Posted by cthames View Post
I had the same problem. this past weekend I took off the valve cover and found my baffles all clogged up. Cleaned up and replaced with new casket and new air filter and have seemed to solve the problem!
I haven't taken my Valve Cover off in a long time, since we first tried to fix the problem, about a year ago, thinking it was the Valve Cover Gasket that was leaking. Since I cannot remember, and for the life of me I have no idea what a "Baffle" is.

Is it that flat metal plate that is at the top of the Valve Cover?
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