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

[RedHeep]

The hardest part about changing those bearings is taking the pan off.

You're going to kick yourself if you don't change them now and try to bandaid it. Taking the pan off twice after you didn't fix it the first time sucks. Ask me how I know . . .

 

[LIFT3Ð_XJ]

Anyone already suggest priming the oil pump? I finally got to talk to the guy who i bought the jeep from and after putting 2 quarts of Lucas in and changing out the fram filter and the sending unit the pressure on the gauge is the exact same. I told him all of that information and he said it was most likely the oil pump needed priming. So i researched that and got several messages that state you need to do what on this page :

http://www.golenengineservice.com/html/jeep_tips.html

Basically rotate the distributor insides until you feel pressure or see it on the gauge.. anyone ever do this?

Anyone think this is what his problem was? or mine?

 

[Ecomike]

The hardest part about changing those bearings is taking the pan off.

You're going to kick yourself if you don't change them now and try to bandaid it. Taking the pan off twice after you didn't fix it the first time sucks. Ask me how I know . . .

OK, so How do you know??? :laugh3:

 

[ghettocruiser]

Anyone already suggest priming the oil pump? I finally got to talk to the guy who i bought the jeep from and after putting 2 quarts of Lucas in and changing out the fram filter and the sending unit the pressure on the gauge is the exact same. I told him all of that information and he said it was most likely the oil pump needed priming. So i researched that and got several messages that state you need to do what on this page :

http://www.golenengineservice.com/html/jeep_tips.html

Basically rotate the distributor insides until you feel pressure or see it on the gauge.. anyone ever do this?

Anyone think this is what his problem was? or mine?

Priming an oil pump using the method on that page is common practice. Ill be doing this after its all buttoned up. It is most certainly NOT my problem though. In fact...I didnt prime my oil pump when i changed it out in my 94. It had pressure about 1 sec. after the motor fired. A lot of people say to pack the new oil pump with vasoline...I might try that this time...

But you should never have prime your oil pump again once you have the engine together and running... If you do, then something isnt right and all the oil is somehow draining out of your pump.

Im leavin work in a couple hours to go home and inspect the other bearings. Im leaning towards replacing them all...since I already have new bearings from fed. mog. Ill let ya know what I find!

Justin

 

[Ecomike]

I should have thought of this before, but it is also possible that the high pressure relief valve on your old oil pump was on the fritz and dumping pressure intermittently.

Might be interesting to dismantle the old pump.

Are you installing a high flow pump? If not, you might want to consider it!

 

[ghettocruiser]

Yeah I intend to investigate the pump when its out. In fact, Im going to remove it first thing when I get home. Its kinda in the way and dripping oil all over. I dont know much about the internal workings of an oil pump, but I guess what you are saying makes sense. Ill take some pictures of it and all that jazz.

I bought a melling high flow pump to intall. Came with a new pick up tube. Same thing I installed in my 94 and its worked great. Funny thing is... A standard melling replacement is $75. Then the pick up/screen is extra. The high volume is $75 and it comes with a new pick up and all. Just makes sense to get that one...

Justin

 

[Dr. Dyno]

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

Since you already have new bearings in hand, replace the old ones, otherwise you could be kicking yourself afterwards for not doing it.
Yes, it does seem that the ticking noise could have been the lifters running dry and not pumping up.
As for the oil pump, even if there's nothing obviously wrong with it on inspection, you could find that the pressure relief valve was sticking open.

 

[outlander]

I have had issues with Purolator filters in both my 4.0XJ and my 2.5TJ,

I have never heard anything bad about purolator,thats all I've ran for 10 years.What kind of probs did you have?just out of curiosity......:dunno:

 

[ghettocruiser]

Ok guys... Well...I found the first bearing issue. The third bearing from the back had a nice groove all the way around it. Atleast on the bottom half of the bearing. Looks like something came in through the oil inlets in the top half. Oddly enough, the crank still feels completely smooth, and the areas on either side of the groove look perfect on the bearing. So I decided that the crank would be ok since it was still fine. All the other bearings I pulled off on the mains besides the first two that I did looked perfect. No lines, no little specs, no copper...they were flat and smooth. Good sign...

Now..onto the rod bearings. Bottom halves looked "ok"... They seemed to have wear but not much. The top halves had copper showing through. Quite a bit. Not all the way around the top half..but a good bit of it. I assumed that since on the upstroke the crank is pushing up on that bearing...and during the power stroke the rod is pushing down on that bearing, that it would wear quicker than the bottom half. So again..Im not sure if thats normal for a 127k motor or not. Either way the crank looks good. Im gonna try some plastigage most likely just to make sure the crank isnt worn.

The oil pump seemed ok. Alittle bit of a deposit in the pick up screen. But I dont know that it would have clogged it to the point that Ide loose pressure. There wasnt THAT much in there. I took it apart, but like Dr. Dyno said...I couldnt find anything obvious.

I didnt get to pull all of the rod bearing caps last night. Not to sound like a baby, but I got too cold. I have a concrete garage floor and that thing holds in cold and damp like nobodies business. Im in no real hurry to finish up since my parents are away on a long weekend. And now that I know Im going to just replace bearings and the oil pump...I should be able to finish up next week. I was way too dirty to take pictures..so Ill just take pictures of all the bearings after they are out.

Thanks again for all the help!

Justin

 

[xjbubba]

Let us know what you find. I'd expect the oil pump is the problem; could be as simple as a broken pressure relief spring inside the pump housing, bypassing most of the oil.
In my experience, the first noise you here with low oil pressure, in an engine with hydraulic lifters, is the rocker arms pounding on the valves. Without oil, the lifters collapse, resulting in too much valve clearance, leading to "clacity-clac".
The cylinders are generally oiled via squirt holes in the rod caps, so, yes, loss of oil pressure reduces/stops cylinder oiling. Scored cylinder walls are a good possibility, depending on how log the engine ran after loss of pressure.
If it were me, and I saw any sign that the crank is scored (run thumb nail over journals--you feel any roughness, it's scored), I'd pull the engine, and do a complete rebuild, or short block.

 

[Dr. Dyno]

It seems that Justin didn't run the engine with zero oil pressure long enough to cause severe internal damage but he'll certainly need to replace the rod/main bearings and the oil pump. The upper halves of the rod bearings are always under the most stress so it's normal for those to wear out first. The cam bearings are usually the last to wear 'cause the cam spins at only half the speed of the crank and they don't take as much side loading.
The oil pressure relief spring inside the oil pump could indeed be broken or the valve could simply be stuck open but either way, you'll need to replace the oil pump anyway.

 

[ghettocruiser]

Ok guys. Some updates and lots of pictures... Last night, even tho it was friggin bitter outside, I got the main bearings done. Everything went smoothly. Bearings all slid out without issue. All crank journals looked smooth and clean.

I loosened all the main caps to allow the crank to drop, per a suggestion from my friend. Which it didnt drop at all...and had me scratching my head for a bit. Til I realized that I had the belt on still. Took the belt off and it dropped a good bit. Allowed the bearings to slide out from the top without much issue. Everything got clevite red assembly lube.

I also replaced the rear main seal while I was in there. Mains are all torqued to spec and when I spun it over by hand everything felt great...nice and smooth. The next step is rod bearings. Which, if the weather doesnt warm up a tad, isnt gonna happen real soon. Anyway...onto the pictures. Ill describe as I go..

Starting at the front of the block. #1 bearing... That mark is sharpie where I tried to write a 1...not damage.

#2

#3...the Thrust Bearing

#4

#5...This is the grooved bearing. More pictures of this to follow on the next post.

 

[ghettocruiser]

cont'd...

#6

and lastly #7

Here are some more pictures of the damaged bearing. I dont believe this happened due to the oil pressure incident. I have a feeling its been like that for awhile. Also, I found no damage on the crank journal...beleive it or not. Smooth all the way across...no ridge while scraping with finger nail.

I posted all these pics just to kind of give a reference to what a 127,000mile 4.0 that's been decently maintained looks like. Maybe someone that opens up their motor for the first time can kind of get an idea of what they look like. I dont think they look bad. None of them besides the grooved one had any ridges or gouges. And only a couple had those little specs...like the pictures I posted awhile back.

Ill update again when I have some more progress! Thanks again for all the feedback!

Justin

 

[ghettocruiser]

Just as a refresher...

What it sounded like after the pressure problem...

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

What it sounds like as of now... New mains, new rod bearings, new oil pump...

http://www.youtube.com/watch?v=rxWB4kTib2w

...by the way the only sound that you can hear out by the engine is the injectors ticking away. I fired it last night, let it run for awhile at idle, then shut it down for the night. The video was taken today after i let it warm up alittle bit.

All the rod bearings were copper on the upper half. Bottom halves were fine. Surfaces felt good though. All the crank journals were good to go I think. I can take pics of the rod bearings if anyone wants to see them...just didnt get around to it tonight.

Fired up on the first shot, had good oil pressure, quiet as the day we got it. All in all.... I replaced the main bearings, rear main seal, rod bearings, oil pump, oil pump pick up, and all associated gaskets.

Took it for a drive tonight and all seemed well. Im going to let it sit tomorrow, and drive it around some more. Then start taking it to work and put some miles on it this week before giving it back to my mom. I plan to change the oil and filter again in about 500 miles. Let some break in happen.

So...not sure if my loss of pressure caused any severe bearing damage. My take on the situation is this. I think the pump failed one way or the other. Because I DEFINETLY lost oil pressure. I think the lifters pumped themselves dry, and caused the motor to run rough. Which is a good thing because thats what caused me to look at the gauges. I think all the noise after I got it home was the dry lifters slapping around, and probably some bearing wear. Definetly worth the time to do all this work if it keeps running good. Even if we get another 50k out of it, Ill be happy.

Any comments still welcome!

Justin

 

[Dr. Dyno]

Even if we get another 50k out of it, Ill be happy.

That's plenty of time for you to start planning a stroker.

 

[WarnFleXJ]

Being an independant shop technician I have found a bunch of oil psi switch's to be aslo. I believe the proper diagnosis would be to check for the proper voltage at the switch and then a resitance check, It looks Like Mr.Dyno would know about the Diag. procedure

The key question is was your engine making any knocking sounds when the oil pressure was zero? If not, it's unlikely you spun a bearing because if you did, the engine would have been knocking pretty loudly.
I think you'll have to pull the oil pan off, inspect the rod/main bearings, and replace the oil pump. I suspect that by pulling off the pan you'll find the reason for the zero oil pressure.

 

[UNCC_99XJ]

Sounds much better!

I'd like to see those pics of the rod bearings when you get around to it.....

 

[Rafa]

Sounds much better!

I'd like to see those pics of the rod bearings when you get around to it.....

x2

Rafa

 

[ghettocruiser]

Hey guys. Yeah it sounds MUCH better. Ive been driving it around and all seems well. Its very smooth, and very quiet. When I first start it up while cold, oil pressure is steady at around 50-55psi. Stays there. After its warmed up all the way, pressure while stopped and idling is 30psi, and while driving is a constant 40-45 psi. So I think everything is going good so far. Ive been taking it real easy on it... Figure I would baby it til the 500 miles are up, change the oil and filter, and hand the keys back over.

As for the cause of all this...I think the pump failed. I took a 5 gallon bucket, and put some new oil in the bottom. Just enough to submerge the pick up. Put the old pump in the bucket with the input shaft chucked onto my drill. Oil came out...but it was in consistant and kinda weak looking. Hard to explain. Then I did the new pump, and it actually bogged the drill down once it sucked oil in, and almost shot oil all over me. It came out a lot stronger, and when i slowed the drill down, the amount coming out was nice and consistant. I took the old pump apart, and I honestly couldnt see what could be wrong. But all I know is, it didnt bog my drill down like the new on did, so something is weird with it...

I found some bearing issues while in there, but I think everything was pre-existing to this oil pressure failure. Ill take some pics for you guys that want to see the rod bearings. I should get a chance to do that tonight for ya. I wont do them all like the mains, Ill just snap a few.

Cant say that I had fun doing this...but it feels really good to have saved my mom alittle money. Well... alot of money... Be able to work on cars has a ton of financial benefits!

Dr. Dyno...50k is plenty of time for her to save up and get another car The stroker plans are for my jeep..which may actually happen this summer. The gears in my head are turning, just need my wallet to spin with em.

Being an independant shop technician I have found a bunch of oil psi switch's to be aslo. I believe the proper diagnosis would be to check for the proper voltage at the switch and then a resitance check, It looks Like Mr.Dyno would know about the Diag. procedure

Not sure why we are still talking about the oil pressure sender? There was never a question in my mind that there were actual physical issues, not just a sender/gauge issue. DR. Dyno's quote was basically telling me I wont know til I tear it apart. Which was correct, and in the back of my mind I knew that... Heck, even after tearing it apart I still dont have 100% confirmation on what went wrong.

Thanks again for the feedback everyone! Keeping my fingers crossed that it keeps running like it is now. Its kinda weird to drive it because its so quiet. With the hood up all you can hear is the fan whirring and the injectors ticking away.

Justin

 

[Andy in Pa.]

Being an independant shop technician I have found a bunch of oil psi switch's to be aslo. I believe the proper diagnosis would be to check for the proper voltage at the switch and then a resitance check, It looks Like Mr.Dyno would know about the Diag. procedure

Justin, I literally spewed coffee when I read this....

Let me be the one to get you up to speed on this thread....

ITS NOT THE FRIGGIN OIL PRESSURE SENDING UNIT!!!!!

Wow....