Oil Leak and Oil Pressure


SirDoopYJ

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Now that it seems I have my cooling figured out, I can now move on to the next big thing which is oil.

My main issue is that I am either leaking it or burning it. My oil level gets to the bottom of the safe line after driving it for a few days. I have topped it off many times since purchasing it in October.

My biggest guess right now is that it is coming from the valve cover. I have caked up oil on the front of my transmission under the firewall. This weekend I plan on pressure washing it. I am just afraid to do it around the valve cover because of all the wiring. I can probably just go ahead and change the gasket out anyways.

I also have low pressure in cyl 6. I think it was between 110 - 120. Why I have low pressure in just that one cyl I don't know. Is this usual? Unusual? My other cylinders were around 145 - 150. I haven't done a leak down test yet. I also show no signs of oil burning from the exhaust.


My other issue is my oil pressure gauge is acting weird. My pressure is usually around 35 to 40. Which is normal, but when I am driving and begin to slow down my gauge starts to rise to 80 when my Jeep shifts near 2nd gear. (I have an automatic, don't shun me.) When it starts to rise to 80, I noticed that when I start giving the Jeep gas again, the gauge will lower back to 40 at the rate of my rpm. If I let go of the gas it raises back to 80, if I step on the gas it lowers to 40.

Now with that being said. Sometimes it is the opposite. I give it the gas it rises to 80 and if I let go of the gas it goes to 40, but this doesn't happen as often as what I stated above.

The first thing I am going to inspect is the wiring, which I have learned from Macho, is that it is one grey wire leading all the way to the sending unit. My sending unit seems fine, and is brand new.

I also noticed my gauge shooting up to 80 when my dad was messing with my vacuum tubes on my manifold and messing with the wiring near the throttle while the Jeep was idling. Maybe I have a bad connector or a leaky vacuum? I don't know if this is a factor or could be a factor.

In the video below I record my pressure gauge. Disregard my volts. This is not my original cluster. This is the used one I bought online for the temperature gauge. I just had it plugged in at the time and wanted to see if the oil pressure gauge in it did the same thing to make sure it wasn't specific with my gauge or wiring.


Edit: I am also driving in my yard. I am not on the street!
 

Flyer58

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That's a head scratcher.

Does anyone know if the air pressure in the crankcase can affect the oil pressure. Maybe if a PCV valve is sticking it's causing the oil to collect in the valve cover and a shortage in the sump.
 

Gilaguy23

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There is no "PCV" valve actually. Although Im talking about my 4 cyl in my 91 and I think the 4.0's are the same. So, Its a open passage in a brass fitting that screws into the valve cover. That small plastic line making its way to the intake is the line the vacuum comes from. I for one often clean out the passage with a small wire or drill bit that something like 3/32" The orifice is pretty small and you dont want to drill it out bigger, just clear it out. I also blow out that plastic line from the VC to the intake with my air compressor as it gets clogged up with junk. Prior to doing this I would get oil weeping from the oil fil cap and probably the V cover before I changed the gasket.
Far as oil loss goes consider your adding 1/2 qu or so to fill it back up to full. Thats a lot of oil to leak every few days but only you know how bad that leak is but Id think you'd have pretty big puddles under the thing every time its parked from the oil dripping off the trans and back of the engine. The gauge.....Cant say mine is any different. Used to work correctly then went to pegged to reading right then not its pegged when ever the key is on or its running at any rpm. One of these days I'll track down the bad ground or just install a after market oil and volt gauge.
The compression, well yes, thats not great. Generally its a case of percent of difference between all of the holes. In your case its just #6 thats out wack. Hard to say why its low on compression but it is the rear where it is hotter and perhaps in its other life just neglected on oil changes etc. With regard to Flyers question, no, a bad PCV valve would not cause oil to sit in the head and cause cavitation of the oil pump.
Oh and that auto trans....I used to be a Id NEVER own a auto dude, but anymore Id take an auto over a stick in a 4x4. You can set up an auto to be pretty indestructible anymore. Better for 2 foot driving in the rocks and easier on the drive train with its fluid cushioning.
 

Flyer58

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Same for my 92 2.4l and mine was plugged solid, in fact the entire valve cover was solid peanut butter. I didn't look at the profile and now see it's a 93 4.0 so that rules out my guess. It's also not exactly RPM related. I don't trust these oil pressure sending units as I'm seeing more report of them leaking and tossing all oil over the road. That's what happened to mine with the previous owner and ended up trashing the engine.
 
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SirDoopYJ

SirDoopYJ

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What I'll do is keep track of my driving time and gauge how much oil I am putting in to get a more accurate assessment, but like you said it is a good bit. I don't have a big puddle underneath though. Just to spots, one for oil and one for transmission. They should make Jeep diapers.
 

Gilaguy23

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"They should make Jeep diapers". Pitiful as it, is Ive used the oil absorbent pads (Jeep depends) strapped under the engine to keep a leak from making a nasty mess till fixed it.
 
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SirDoopYJ

SirDoopYJ

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You got the Delta Vid??
Right now I have no symtoms, I am getting tested tomorrow. I was in close proximity with my grandmother who tested pos. My grandmother found out yesterday at a dr appt, she is also showing no symptoms so we had no idea. I told my boss as soon as I found out and sent me home. So fingers crossed I test neg. I still have a week to go to get my 2nd dose
 

machoheadgames

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I would guess you're burning it as a leak of that quantity would probably be very visible. although you would think you would have blue exhaust smoke but sometime it isn't the case, so it's hard to say. Not sure what's up with the compression on cyl 6. Could be bad rings, I really don't know.

As for the oil pressure gauge, is this the oil pressure gauge on the newer cluster (the one with working water temp?) And it's acting the same as the other ones too? If so, you may try another sending unit despite the existing one being new. You might try to source out a good brand there too. Mopar for 1994-1995 is 56026779. I see 56026779AB is available. don't know why 1993 used a different one and it's only made more confusing at the parts stores where they sell 5 different ones with no telling the differences between them other than appearance.

Your oil pressure fluctuation is like none I have ever seen and to me, no way that is real. Oil pumps grow weaker as they wear and get older, they don't cause random fluctuation like that. They are a simple mechanical part. This screams bad gauge/sender issue, which given you have tried two known good clusters, I'm placing bets on the sending unit.

I would try the 56026779AB here. I see no reason why it wouldn't work, it's the same 1 terminal sender that I have and I know the gauges and sender function didn't change from 93 to 94. disregard the amazon pic, it is wrong but the reviews say you get the right part.
 

Flyer58

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Stay safe and hope all goes well for you

Try accelerating the YJ up to 50mph or so and take you foot off the gas pedal. After it coasts down to 20 mph step on the gas hard again and look for a blue cloud in the mirror. That may help determine if it's worn valve guides or rings.
 
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SirDoopYJ

SirDoopYJ

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Ordered the Mopar sending unit and I tried doing the blue cloud test, but I saw nothing.

I will go ahead and change out valve. After that I will go ahead and do RMS and replace oil pan gasket. I may go ahead and replace oil pan too. It is dented in.

@machoheadgames do you have a part # for the bearing brace that the TJ 4.0s started using?
 

machoheadgames

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Good luck.

53020566 for the girdle. You need the stud bolts also and they need to come with nuts.

here looks like a good set. Cheaper than I got mine and looks to be just as good of condition.

Girdle kit on eBay

change the bolts one at a time making sure to torque in steps. Torque is 80 ft lbs, I did 40 first and then 80. Do that for all the caps, then put the girdle over the studs, put a few nuts on, then put them all on and torque to 35. It’ll probably take you a solid hour to change out all the bolts. Lots of unscrewing and screwing in a very uncomfortable position under an oily engine. Worth it though, I think it’ll run smoother.
 
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SirDoopYJ

SirDoopYJ

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I moved my Jeep into the shed to get started on the RMS change. I haven't had a chance to drain the oil.

I haven't touched or moved my Jeep since Sunday. Here is my oil puddle for the past 6 days.

20211030_103544.jpg20211030_103533.jpg

Is this enough to say this is the main spource causing me to refill about a half qrt to a full qrt of oil every two weeks?
 

Gilaguy23

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So you went for a drive and parked it and that what you get? That significant amount and definately noto helping diagnose the loss. Do make sure its not a bad drain plug gasket,or bad V cover. be a heck of a lot easier then a RM job. Regarding the oil pressure. if its like my 91 Id pull the cluster and where that flat connector plug is clean the tabs like new. I also used a pair of needle nose pliers to flatten out the tabs as they had groves in them of sorts where the contact were made. My OP gauge 95% of the time said 60 all the time with the occasional needle flutter to 40. After the cleaning of the tabs,adding a additional ground wire it then said 40 at speed and almost 0 at idle after warmed up, it also corrected my volt gauge being in the red most of the time. I got tired of farting around with it and installed a mechanical gauge. So with the factory and aftermarket OP gauge I see 40 max at speed and 0 at idle and on the other its 55 psi at speed and 20 at idle.
Now the part you dont wanna hear. Id also ignor what I post because Im 99.9% sure its not your issue. I have a 89 Bronco with a 302. Drive/cruise unloaded at 55 and the O/P was low at 35 (engine was tired)hit the gas and it would shoot up about 10 psi. Let off the gas as It basically coasted down a couple mile long grade while commuting to work and the O/P would go up to 60 or so. I tested it with a manual gauge as well with the same results. The only logical conclusion we came to was the either the cam was walking forward or backward due to a worn thrust bearing or bottom end bearings were so loose the same was happening somehow causing the issue. The only thing we could figure out.
 
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SirDoopYJ

SirDoopYJ

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I haven't driven it since last Sunday Oct. 24th. It sat in the shed for 6 days, so I really got to see how much it drips on it own. The drips are coming from between the trans and motor. I was prepping to do the RMS and oil pan, but we had a family emergency and didn't get to it. All is good with the emergency.

I have already changed the Valve cover gasket, because it appeared it was leaking from the backside. My oil pan is dented and it looks like it could use a gasket change. While I had that off I was going to go ahead and change the RMS along with adding a girdle.
 

machoheadgames

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I don't know if I would say it's "a lot" but it's certainly worth fixing. It's only going to be worse when it's on the road and the engine is sloshing oil all over the place inside the pan and under the crank.

I expect you will see a pretty dirty engine backside when you do your trans swap. Good thing is that will give you plenty of room to observe and clean up back there.
 
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SirDoopYJ

SirDoopYJ

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I started removing the bolt of the starter to get it out of the way before I put my oil pan on. As I was removing the bolt, something clear started leaking from the starter bolt hole. I am not sure what it is. It seems like it may be water?