ZERO oil pressure, What can I expect to find??

[Ecomike]

OK...looks like the vid is up.

So here is what happened. I know I did some damage to the bearings. Just by the amount of noise it made and how rough it was running. So I decided to fire it up for a few seconds just for the heck of it. And to get you guys some video. Well, it fired right up, made a lot of noise, then to my surprise quieted down. You can hear it in the vid... You can see how surprised I was because I went to look at the gauge. Sure enough..oil pressure. The motor was still making a racket. After the video, I watched the gauge as I revved the motor to about 2000 rpms real quick and let off. Oil pressure went right to zero for a few seconds, then slowly back up to ~35. Shut her down after that.

My thoughts are...the oil pump failed. That would explain the fluctuation in the oil pressure. I can hear something weird too...that sounds like a whirring noise. I kinda of thought maybe since the oil was so cold and thick from sitting, that it was thick enough to have oil pressure at first. Which is why it had pressure, but was really unstable. Anyway... the only way Ill know how much damage is to tear into it. But Im hoping that I might be able to get away with a crank kit at this point...

Here is the vid... Ignore my stupid commentary. haha.

http://youtube.com/watch?v=-GlQsYMI5RQ

Justin

I'm a bit suspicious of your conclusions at this point. Oil pressure normally increases at increased RPM. The fact that the oil pressure was higher at idle and went to zero at higher rpm makes me think something else might be wrong, like the oil pressure sender, or a clogged (clogging) oil pump inlet screen.

Just for the hell of it why not pull the distributor cap and check the rotor and the inside of the distributor cap to see if something wierd is not going on under the cap like a damaged rotor, or damaged distributor.

Some one else correct me or back me up here, but doesn't the bottom of the distributor shaft turn the oil pump!!!??? and the distributor gear on the distributor shaft is turned by the cam shaft?

Before I pulled the oil pan I would inspect the cap and rotor and then pull and fully inspect the distributor (real easy fast job) to see if it is involved in the problem before moving on to the oil pan and pump.

 

[PaulJ]

I'm suspicious of the conclusions also. I have a hard time imagining a mechanically driven oil pump that is intermitent.

 

[RichP]

Thats the main reason I suggested spinning the pump up by drill. Also I lost a 2.8L to a clogged oil pump pickup. Intermittant oil pressure also, oil pressure dropped at higher RPM's as the pickup sucked up sludge, shut it of, start it up and normal idle pressure returned till you got around 2K then it would start to drop again. End result, don't just replace the pump and some bearings, pull that dist to see if the key on the end of the dist is worn. Distributors can wear out.

 

[ghettocruiser]

Hey guys. What you are all saying makes some sense. I had this same thing happen to my 94 awhile back. Just to clarify...the oil pressure doesnt go to zero while the motor is revving up... as the motor returns to idle the pressure will quickly drop to zero then come back up again. I solved the problem in my 94 by replacing the pump...

However, I think my problems extend further than the oil pump at this point. The motor makes quite a bit of noise and Im confident that the bearings took a beating. Since this is my mom's daily driver, Im still going to pull the pan and check things out. I dont want something to happen while she is driving it... Ide rather replace the crank and bearings now while its down, than just do something simple to hold it together for another 500 miles.

I will check the distributor shaft....but Ive never seen something like that happen. Especially with the short shaft at the 4.0 has. Just doesnt seem like there is enough resistance there to cause major wear. I just did a tune up on it not too long ago so Im willing to bet the inside of the cap are still new looking. For the 5 minutes it takes to pull the dizzy...Ill do it just to rule that out as an issue.

I went today and picked up a new oil pump, oil pick up and screen, a few filters so I can do an oil change after it runs for a little while, and a new pan gasket. Figured I might as well get the parts so I have them. If I dont need them then Ill take em back. If/when I pull the pan off, I wont be putting it back on without atleast replacing the pick up and screen...

I think Im going to start to investigate tomorrow afternoon as long as its not too bitter cold outside. But I have a feeling its going to be pretty cold. So we'll see. Ill keep you guys updated and keep any suggestions coming.

Thanks!

Justin

 

[AkJeepKid]

Oooooh! I've heard that noise before! In my '85 AMC eagle! Needless to say I ran it til the engine blew which was.... bout 3 months later.

The most I did was take off the valve cover cuz it sounded like a valve spring or something lose. Plus I was driving the car until it died so I could have a real reason to get the jeep runnin

Good luck and keep us posted on your finds.

 

[Ecomike]

OK...looks like the vid is up.

So here is what happened. I know I did some damage to the bearings. Just by the amount of noise it made and how rough it was running. So I decided to fire it up for a few seconds just for the heck of it. And to get you guys some video. Well, it fired right up, made a lot of noise, then to my surprise quieted down. You can hear it in the vid... You can see how surprised I was because I went to look at the gauge. Sure enough..oil pressure. The motor was still making a racket. After the video, I watched the gauge as I revved the motor to about 2000 rpms real quick and let off. Oil pressure went right to zero for a few seconds, then slowly back up to ~35. Shut her down after that.

My thoughts are...the oil pump failed. That would explain the fluctuation in the oil pressure. I can hear something weird too...that sounds like a whirring noise. I kinda of thought maybe since the oil was so cold and thick from sitting, that it was thick enough to have oil pressure at first. Which is why it had pressure, but was really unstable. Anyway... the only way Ill know how much damage is to tear into it. But Im hoping that I might be able to get away with a crank kit at this point...

Here is the vid... Ignore my stupid commentary. haha.

http://youtube.com/watch?v=-GlQsYMI5RQ

Justin

I have a jeep with a Nissan Diesel (SD22) engine that I thought was toast for sure last year. It blew tons of billowing thick white smoke out the exhaust and ran like sh#!. Took it to a diesel mechanic and he said he thought the injector pump was bad.:tear: He wanted $500 just to pull it and send it to another Bosch Dist, for testing to see what it needed. Anyway I later found some Nissan guys online (another group like this group here) that helped me figure it out. Turned out it was just a $27.00 leather diaphragm:woohoo: in the pneumatic governor of the fuel injector pump that was bad. Took 30 minutes to fix. Runs like a new engine engine now! I was almost sure I needed a new engine at first though. My point is don't be too quick to write of the engine and bearings, just yet.

I would sure check that distrubutor top to bottom before restarting the engine again!

You said it only has 127,000 miles on it and was well cared for, any chance the oil drain intervals went to long at one point and it sludged up real bad? I find it curious that it was well cared for (your words earlier)....(meaning to me regular timely fluid changes) and yet the water pump seal went out at only 120,000 miles!

Also, I have read others postings here telling horror stories of wierd stuff going on inside a 4.0 distributor cap shortly after tune ups, like rotors melting! Making weird noises and running really poorly. Just because you have not seen it before doesn't mean its now there!

If, when you pull the pan, be sure and plastigauge all the bearings you can reach (mains and lower rods for sure) while the pan is off.

 

[ghettocruiser]

I consider 120k pretty decent for a water pump actually. I had two other friends within the past couple years have to replace their 4.0 water pumps at around the same mileage.

And as for oil change intervals...Im sure it went alittle longer than 3k several times, but not by much. Its definetly well taken care of...because I do all the maintenance on it. And considering how it has NEVER needed anything besides tires and brakes and a water pump...I think thats pretty good.

Funny you mention the melted rotor. I just posted about that happening on my 94 not too long ago. Again, Ive never seen that happen. Lots of other guys said it was weird as well. I chalked that up to defective parts. I used cheapo autozone parts because I needed them in a pinch. Get what ya pay for I guess.

I just wonder how I cant start to write off bearings just yet? The thing sounds like a diesel motor now. Its most definetly not the dizzy making all that noise... If there is a problem with the dizzy, then Ill deal with that too. But I still think Im going to have some pre-mature wear on the bearings. Enough that would require replacement. I wish you guys could hear it in person...the video hides alot of the ticking and what not.

But we'll see. Ill pull the dist. on sunday first thing just so it can be ruled out. Im also going to drain the oil and cut the filter open. Like I said before, the jeep has never let us down and Ive never had to do anything major to it. So I dont mind pulling the pan just for inspection purposes. Im not afraid of doing some extra work to be on the safe side. Im afraid of trying to get away with doing as little as possible then having it quit again while my mom is drivin it.

Thanks again for all the feedback! Hopefully tomorrow Ill have more for you guys than a crappy video with stupid commentary and my theories!

Justin

 

[Dr. Dyno]

The fluctuating nature of the oil pressure suggests that the oil pump shaft is probably OK. It's more likely that the pickup screen is clogged up and when the oil pressure dropped to zero, you left the engine running too long and damaged the bearings.
Forget about the dizzy. Drop the pan and take a look.

 

[ghettocruiser]

The fluctuating nature of the oil pressure suggests that the oil pump shaft is probably OK. It's more likely that the pickup screen is clogged up and when the oil pressure dropped to zero, you left the engine running too long and damaged the bearings.
Forget about the dizzy. Drop the pan and take a look.

Yeah. I thought about the pick up being clogged. I kind of group that in with an oil pump failure even tho its not actually a part of the pump. I gave it some more thought today, and went out and looked at a spare distributor I have laying around. I just dont see that as a possibility. There just isnt anything there to just fail as far as the shaft goes. I am going to drop the pan. Im going to drain the oil and cut open the filter first. I just want to cut open the filter for curiosity sake.

Ill post pictures and report back when I find out some info. Only time Ive ever dropped a pan on a 4.0 was in my jeep...which is lifted. So Im going to disconnect a few things and try to get the axle to droop as far as possible. If I can get it all apart tomorrow ill have pics and what not tomorrow night.

Thanks again!

Justin

 

[LIFT3Ð_XJ]

My oil pressure on my 90 xj 4.0 shows 40psi at start then goes halfway down after driving for about 5 minutes then goes to 0 the time after it but I always checked it (had it a week) and its quiet still. Some times it seems ti idle a little shakely but i think thats due to miles/age.


I was reading that the oil pickup hose that leads to the bottom of the pan may of disconnected and that would mean as the oil was sucked up to the engine the pump would starve with the oil not reaching the area the hose was connected to.


Just a thought*


-doug

 

[UNCC_99XJ]

The fluctuating nature of the oil pressure suggests that the oil pump shaft is probably OK. It's more likely that the pickup screen is clogged up and when the oil pressure dropped to zero, you left the engine running too long and damaged the bearings.
Forget about the dizzy. Drop the pan and take a look.

I'm with Doc on this one.....it's gotta be something oil pump related such as a clogged screen.

Oh, and I don't wanna ever hear those noises comin out of my 4.0.....ever. That sent a chill up my spine just watchin that video.

 

[JEEPNICK]

Take out the sender and plumb in a mechanical gauge temporarily. You can get ine at any hardware or auto parts store cheaply. Even a water or air pressure gauge will work. You may need a short hose or just use the hose on your grease gun for a flexable extension. You may need a female-female coupler to join the gauge to the hose and the hose should just screw into the block where the sender came out. These are 1/8 NPT size 99% of the time. This should take the guess work out of the pressure issue. BTW the pressure sender failed on my wife's '99 GC a couple of years ago, seems like a common problem and always the first thing to check when suspecting an oil related problem.

 

[artsifrtsi]

For tracking down the noise, use the old stick on thumb, thumb on ear trick... place other end of stick on different areas of motor until it gets louder, that'll be where the noise is originating. (or if you must, get a mechanics stethascope)

 

[ghettocruiser]

Hey guys...thanks for the help... But trust me. I have oil pressure problems. Its not sender/gauge related. The motor started and you could hear it was dry as a bone until it got going and some oil made its way back through the engine. 99XJSPORT06 said it...its a spine chilling noise. haha. Not something I want to hear again.

I can hear where the noise is coming from. Haha. Its coming from the bottom end. Its really obvious when you are in person. The stupid weather has been pretty crappy the past couple days, so it looks like tomorrow might be the day I start to work on it. Im trying to figure out how to go about making room to work under the Jeep. Ide love to pull the axle. That'd be perfect. But too much extra work at this point.

I already have a new oil pump and pick up/screen. I also already have a crank kit on order. So it will be in and ready if I need it. The only way Im going to diagnose whats up with this engine is to take it apart. I have to inspect the bearings and crank journals. No way around that. Im really hoping that nothing is bad in the head or in the cam bearings. Im also curious about the lifters... I dont think I didnt much damage to anything other than the bearings because I only ran it for a short period of time with no pressure. But I guess we'll see...

Justin

 

[Andy in Pa.]

Man, I wish you would quit bellyaching about this and take it apart already!!!! Oh, and I think its the sender:laugh: :angel:

 

[ghettocruiser]

Haha... Waitin on you to bring the beer and the "old man" knowledge over to the garage!

 

[UNCC_99XJ]

Remember....LOTS of pics!

 

[ghettocruiser]

Ok guys. I started to take things apart last night. First I drained the oil...duh... I removed the filter, and cut it open. Tried to filter the oil from the filter as well as look at the filter element. I didnt really see much. I expected to see much more. Just some carbon like deposits. That filter has been on there for about 5,000 miles ide say. They say to change the filter every other oil change...so thats usually what I do. It was a bosch filter...since I couldnt remember before.

Anyway. I pulled the pan next. Didnt find any sludge in the pan. It was all oil and there was nothing in the pan that would be consdered abnormal. The oil pump pickup looked ok but I havent taken it apart yet. After removing the girdle from the main cap bolts, I removed the number one checked it, replaced it...then the number three... I didnt have time last night to check them all because I had to be somewhere.

I have to admit. Im not sure what 127,000 mile bearings are supposed to look like, but these didnt seem too bad. No copper showing at all. They were very smooth to the touch. I could use my finger nail and couldnt feel anything. There were some weird little specs...but Im not so sure that could have happened during this little problem. They are not raised at all. You cant feel them.

So...here are a couple of pictures. These are all pics of number 3. Hopefully tonight Ill get around to pulling all the other main and rod caps off to check them out. I tried to get good pics...but they didnt come out too great. They also make the little specs stand out. It looks different in person...

Justin

 

[Dr. Dyno]

Looks like normal wear for a 127k mile old engine so far. Let's see what the other bearings look like.

 

[ghettocruiser]

Yeah thats what I thought... Im leaving work early today to take the rest of them off and check them out.

Im starting to think that all the ticking I heard and the loss of power was due to the lifters pumping themselves dry. Then not having enough oil pressure to pump back up properly. We'll see.

I have new bearings in hand... Im trying to decide that if there isnt any major wear, and the crank doesnt have any wear, if I should just throw new bearings in it while Im under there and its all apart. There shouldnt be anything different with the crank, so standard replacement bearings should have the correct clearances... But I havent decided if I should do that for sure yet.

Justin