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Unread 09-02-2011, 02:46 PM   #1
rksnow1
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1988 YJ Wrangler 
 
Join Date: Jul 2010
Location: Morrisville, PA
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Loosing Oil Pressure.. Thoughts, where to start?

Hey guys, need a little advice. I have an 88 YJ with the 4.2 in it... this is a project semi-restoration and weekend toy Ive had for about a year. currently has 92k on the odometer. I put maybe 500-1000 miles on it since Ive owned it and oil had been changed several times.

Ive had an oil leak coming from mysterious place since I bought the Jeep a year ago. Nothing bad, just a little drip or two on the pavement and never seemed to burn oil or get low.. I figured I would address it after I finished the body work and was in the garage for this winter. Ive degreased the engine several times and It always is wet with oil again withing a few drives. I cant seem to find the leak anywhere..so Ive dealt with it as everything always has run good until now.

In the last few weeks Ive noticed the oil pressure dropping a bit after a few minute ride.. Starts up around guessing 30PSI (just under the half way point based on factor gauge w new sender) and will drop almost down to the 0 line after a 15 minute light drive. Replaced sending unit. Valve cover gasket was looking wet and decided to change it as well. When I opened the valve cover there was burnt oil everywhere... looked the drippings in my gas grill... bad. Hd the PO ever changed the oil before me? Ive tried to clean it the best I can to get the muck out with a screw driver and rags. Im guessing there is a blocked passage killing the oil pressure or a dying pump. Any suggestions on cleaning these grill crispys out, or is manually still the best way.? I also added some seafoam to the oil in the hopes it will break it down further and get what I couldnt. Im going to pull the pan this weekend and see what the pump and pick ups look like. Waiting on a new gasket. I had the pan off a few months ago and the pickups and pan all looked clean.

Here are my questions:

Any thoughts to how I should clean the old oil "crispys" out of the valve/ cover area? I wasn't sure if I could use a degreaser internally or what it would do to the rest of the motor.

Is there a way to check the pump its self to make sure still good? Ill check the pickups then too.

It was suggested that I should change the rear main seal while Im at it. I was told it was a 2 piece seal and that dropping the journal would give enough room to do this easily.Anyone done this? Can it be done easily. I dont want to attempt and get stuck and have to pull the motor.. rebuild planned for the winter time hopefully

Anything else I should check, do, or clean before draining the oil this weekend to check the pump.

Thanks

Ray

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Unread 09-02-2011, 03:32 PM   #2
oldtime_ironman
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I would give it a full sea foam treatment first, followed by an oil + filter change. Then fire it up and see what happens. Post back and let us know.

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Unread 09-02-2011, 09:33 PM   #3
4.7stroker
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Oil pressure is determined by the main/rod/cam bearings clearance and oil pump only, nothing else has any effect on oil pressure.
Busting loose burnt caked on oil can cause the abrasive junk to cause bearing damage and should be avoided if possible.

Dwayne
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Unread 09-02-2011, 10:44 PM   #4
Quail
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You are going to find that your oil pan is full of that stuff and your pickup is getting clogged by it. The more oil you circulate the more sludge that is stuck to the pickup. If you shut the engine down for awhile the sludge falls off the pickup.
At this point you are going to have to remove your oil pan and clean it very well, clean out your oil pickup and reassemble. DO NOT ATTEMPT TO CLEAN THE MASSIVE AMOUNT OF SLUGDE THAT YOU ARE GOING TO SEE IN YOUR CRANK CASE !
You will have to do that slowly with several treatments and oil changes but you are going to have to restore your oil circulation for that to work, dont remove anymore with the screwdiver.
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Unread 09-02-2011, 10:49 PM   #5
rksnow1
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Whats the best way to get rid of the burnt caked on oil? I could be wrong but Im assuming I just dont want to leave it in there, as I'd think it would get to the bearings eventually and ruin them. I did try and scrap out most of it lightly but this is very time consuming and not very efficient. Im running a seafoam treatment as well for a few miles now before an oil change this weekend to hopefully break it down so not to do any damage.. Can degreaser be used on the valve area, if an oil change is done right after, would this hurt or kill anything internally in the engine?

When I check the pump and pickups this weekend.. If they look clean and the pump spins freely, is that all I need to know it is good? Anything else there I can or should check for?

Thanks for the feedback,
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Unread 09-02-2011, 11:02 PM   #6
Quail
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Honestly, you have set up a situation to do a lot of damage by scraping and loosening that material. If it were mine, I wouldnt start it again until I cleaned out the oil pan, put on a fresh filter and had a couple of fresh filters close by.
While the oil pan is off and you have access to the crankcase you can expeiriment with different oil treatments and see which one dissolves the sludge best.
Its best to that slowly with a less agressive detergent oil additive. Very aggresive cleaners can dislodge very big particles and leave you with unpredictable oil pressure
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Unread 09-02-2011, 11:10 PM   #7
MiNiSaBa
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Before you DO ANYTHING, please check your oil sensor. My oil sensor started to leak a little from the connection and I didn't notice it until my gauge hit zero and I started to diagnose the problem. So before you think the worst, please check the oil sensor.
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Unread 09-03-2011, 12:51 AM   #8
lclark2074
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My first qustion is thare any raps or taps? No raps or taps check for a cloged oil line to the sender unit. If theirs rap or tap check lifters and barings. Now if your planning to use seafome get extra oil filters and oil. Then plain on bying barrings and seals for the bottom end. See if you pull more sluge off the barrings thy will leak more oil into the pan wich will give you lower oil preshure. Now plan on getting an oil pump. If you pull the pan off its a good time to chang the oil pump. Now put the seafome into motor and folow the directions. Drain the oil put an new oil filter and oil into the motor run for 20 to 30 miles. Then pull the oil pan see if theres debree (sluge) in the pan. If theres sluge clean the sluge off of the pan. Put a new gasket glued only to the pan not the block so you can pull the pan agin without ruining the gasket. Put more seafoam in and do it agin .repeat this intell most of the grime is gone. This time check the main baring caps and the rod caps for wair. If thers alot of ware but not bad damage on the crank. You can chang the caps and it will help. THIS IS NOT CONSIDERD A REBULD BUT A NESEARY PARTS REPLACEMENT wich should help. Plastica gage the barings to make shure you have the right ones. Replace the oil pump and put new seals into the motor. hopfully this will fix your leek too. if you still have no oil press take pis and tell us . If you got good presure then drive your jeep 200 miles chang oil agin.
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Unread 09-03-2011, 06:44 PM   #9
rksnow1
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Thanks again for all the feedback. The parts stores in my area were out of most of the parts I wanted.. Oil Pump,Rear Main Seal, and only had one of the needed bearings, but I was able to get a pan gasket, so I decided to change the oil and pull the pan anyway to get a better look at least.

Ran Seafoam treatment for a few miles yesterday, Warmed up and drained oil today, Pulled the pan to find a lot of metal flake/sludge and chunks of what looks like brown glass or maybe plastic, mixed in.. There was 2 finger nail sized chunks of thin silver metal but I couldnt determine where it was from... After cleaning the pan I pulled the oil pump, cleaned It. It spun freely and the metal looked clean inside with no scratches or burrs so I think it is good, Oil pick up was slightly clogged, cleaned it as well. I was going to replace the pump today but as mentioned it is back ordered by a week so I have to wait. I believe my pump was good from what I could see.. Are there any plastic pieces in the pump or pick up that may have broke. I couldnt see anywhere that may of contained plastic, but Im still not sure what the brown glass like pieces in the pan were from? I didn't think there would be plastic inside the bottom end of the motor... This cant be a good sign..

I visually looked at the pistons, journeys, and crank from the bottom and all looked well from what I could tell. Nothing felt loose or shook by hand. I couldnt see any scratches in the piston cylinder walls, no gouges or anything broken.... So after some debate and not wanting to wait a week for the other parts, I Put on a new pan gasket, filter and oil. Expecting a big bang but hoping for the best, I Started it back u.

To my surprise the engine sounded smoother.. Idled nicely around 800RPM for about 5 minutes, no taps, nocks, or strange sounds. Oil pressure was just under the halfway line on the factory gauge(about 30psi Im guessing)higher then before,.... then after another few minutes pressure fell to about the first line on the gauge, Idle doesn't change and still feels smooth. I would think it is the gauge but I just replaced the sender and the shavings and chunks in the pan have me thinking it may be something more severe.. Without pulling the whole motor for a rebuild, where should I start?

Im going to run another Seafoam treatment for a few more miles to help get out any remaining sludge that didnt make its way to the pan yet, as long as no noises or issues appear I'm hoping this will help without destroying the bearings.

There have been a few mentions to replace the rear main seal and or bearings, and possibly the pump. Is there any thing else I can check before replacing half of the parts in the bottom end? Does it make sense to do this without rebuilding the top end? I dont want to spend a few hundred on bearings and a pump if they will fail due to another unknown issue. I plan to put on a 4.0HO head and if money allows rebuilt the engine this winter when I can take it out of the Jeep and have more room to work on it. I dont want to damage anything further but do need it to stay running well til then.

Anyone suggest any oild additives or treatments that may help as well. Also what weight oil are you currently running? Im using 10w40 now, should I go a little heavier or lighter?

Sorry for all the questions, I think Im typing this as Im working this out in my head...
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Unread 09-03-2011, 07:01 PM   #10
oldtime_ironman
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Needs new bearings. No doubt about that. I run 10W30 year round, but if yer at the point where oil weight makes a difference then you have real probs. I would get a bearing kit ASAP, like next week. Theoretically you don't have to pull the engine to do it, but its a lot easier. A set of rod main and cam bearings I could see about $100 for the set.
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Unread 09-03-2011, 07:02 PM   #11
Old4X
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To check the wear on the engine, drop the pan and plastiguage the rod bearings. If over 6 thousandths, that is where your pressure is going. If the crank is standard size, get some 1 thousandths under and 2 thousandths under rod inserts and assemble shooting for around 3 thousandths running clearance.

The brown glass looking stuff is your timing gear coming apart. Pick up a new set of timing gears and a chain and replace.

Be VERY careful with putting solvents in your gunked up engine. Just about all the oil passages are blind ended into bearings. You run a huge risk of starving cam bearings, main and rod bearings, not to mention destroying lifters.

The best alternative is a top quality high detergent oil. Right now, the hands down best oil for this situation is Rotella T (the diesel multigrade ). It will help dissolve, not break loose those deposits. It will take time, but it will get better with each oil change.

BTW, when you change the timing gears and chain, clean out the (probably) stopped up oiling hole behind the cam gear. You will see it once the gear is off.
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Unread 09-03-2011, 07:41 PM   #12
jay-h
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While 92K is young for that engine, the debris you see in the valve cover suggests neglect. you might be able to salvage it with rod bearings or maybe not (worn cam bearings can cause oil pressure problems too). If I weyou I'd swap in a new pump too. You cant tell just by looking if it's good or not.
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Unread 09-03-2011, 09:25 PM   #13
lclark2074
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Think of it this way you put seafome in the motor wich cleans out all the barings out. and then you get bigger gaps wich gives you less oil pressure. so plastiguage and replace whats nessary.
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Unread 09-03-2011, 09:34 PM   #14
rksnow1
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Thanks again for all the info guys! I would never of guessed those glass/plastic pieces were the timing components.. I was just pricing parts... timing components, bearing kit, gaskets, oil pump etc, etc and found its not much more to do a full rebuilt. I found a full rebuild kit for $339 shipped on ebay. I think I may have to bite the bullet and do a full rebuild a little early. Ill be cutting my jetski season short not having a tow vehicle, but I just hate doing work twice.

Wife"s gonna kill me, I just got one project car out of the garage after 6 yrs..lol, but think maybe Ill just go ahead and get it out of the way now. Ill start another thread on the topic but does anyone have any experience good or bad going with a larger bore piston in the 4.2? The rebuild kit Im looking at has larger pistons and bearings available as well... I still plan to put the 4.0 HO head on as well. Figured a little extra power never hurts...

Thanks again!
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Unread 09-04-2011, 01:01 AM   #15
Desert_Rampage
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If you do decide on the eBay way, be sure the parts are reputable. Ie: Felpro Gaskets, Sealed Power rings, etc... Not some "Made in Malaysia" junk. If I recall, NAPA or Advance Auto have Master Rebuild Kits for ~$550.
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