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Oil Pressure question

Good question, I would like to know too.

I have heard of coolant in the oil causing low oil pressure where the coolant leak could be caused by a head gasket leak.

I am not really sure how hydraulic lifters work (how they are layed out) or if the 4.0 has hydraulic lifters (?), but I am suspecting a problem in the camshaft / lifters (if they are hydraulic) on my engine as I seem to have a fairly tight engine in all the other areas now, except possibly the upper rod bearings.
 
Ok I draine one quart of oil and added lucas it and it added increased pressure. went from 0 at hot idle to seven. thinking about about adding more lucas to see if I can get it up to at least 13. Thanks for the help
 
Rich P was on a right track. When I got my 98 XJ the previous owner changed the oil at the local Super Lube with 10w30 Pennzoil and a Pennzoil brand filter.
Cold oil pressure was 40 at speed /20 at idle. Hot oil read 30/10. Once I changed the oil to 20w50 Castrol and installed a K&N oil filter, the pressure increased to 45/40 cold and 40/25 hot. Gotta think that cheap Pennzoil filter was the culprit for the scary low pressure at hot idle.
 
If you don't want to spend the extra $$ on a K&N filter, you can't go wrong with the Napa gold line. Cost about $6-$6.50 around here and i've not had one issue with them. I run them on two Jeeps and a Silverado. My oil pressue is at about 20 HOT idle.
 
I had that same problem with FRAM filters. The FRAMs also tend to leakdown and it takes longer at start up to develop pressure. I use NAPA silvers, which as far as I can tell are the same inside as the gold Napa/Wix filters except the paintjob and price.
 
Sand-Dog said:
Rich P was on a right track. When I got my 98 XJ the previous owner changed the oil at the local Super Lube with 10w30 Pennzoil and a Pennzoil brand filter.
Cold oil pressure was 40 at speed /20 at idle. Hot oil read 30/10. Once I changed the oil to 20w50 Castrol and installed a K&N oil filter, the pressure increased to 45/40 cold and 40/25 hot. Gotta think that cheap Pennzoil filter was the culprit for the scary low pressure at hot idle.
Click to expand...

Why? How do you know it was the filter and not the higher viscosity oil that raised the pressure?

It would be interesting to see data on all the pressures of both oils and both filters in all four possible combos!!!
 
What year, and engine is your jeep.
 
raypla said:
My XJ is having the same symptoms....
Click to expand...

Exactly what "Same symptoms" Details please!
 
Okay, I'll give just a little background. '89 XJ 230000 miles. I replaced my oil pump with an all steel HV pump from autozone too. Oil pressure is great now. Your clearances in your aluminum bodied pump could be just too great once the oil has warmed up and thined out. Something to think about. Oh, and like everyone else STAY AWAY FROM FRAM!
 
99' 4.0
Up until last week my oil pressure was 50-60 cold idle 40 warm and 50-60 @ 2000 rpm w/Ford 5.0 Purolator pure one filter 125,000 mi.

Symptoms - this happened last week, I came to a stop and all of a sudden the check gauge light came on and the oil pressure dropped to 0. So I changed the oil, the pressure went to 40 when cold and would stay around 40 when driving. But this morning on my way into work I started the Heep up and the pressure went up to 40 when cold and as it warmed up it slowly dropped to the point going down the highway at 2800 rpm the gauge was @ 0.

The engine makes 0 noises, burns mo oil and it is still new looking, makes zero unusual noises. So I was hopeing that this was going to be the answer. I searched and saw many threads of similar probs. and I felt it uneccasary to start a new thread.

Thanks,
Ray
 
Change the filter next. I could be a low pressure relief spring setting, which is one of the notorious problems with Fram, along with cardboard end caps.

I have used Slick 50 to raise oil pressure - one bottle usually jumps it 15-25 pounds. The teflon apparently slows down the sling off from worn bearings, and works pretty well even when you let 5 quarts leak out and see the light on. It's been years and the pressure is still up, despite changes every 5k, which makes me wonder about the "re add" suggested every other change.

I have also used Lucas - it made my lifters rattle when cold because it is largely a viscosity index booster. You can run a full crankcase with it - but I don't even want to know what kind of mileage you might get. Lots of people swear by it just like STP in the day, so I take that with a grain of salt. Especially when I asked my former boss at the auto parts house if race cars would use it and he said "Why? You already got 50 wt in the motor." High viscosity oil is there to protect the engine at high temperatures, not because you want to waste power pumping it. You gotta finish to win. So Lucas is no big deal to me. I'm not turning this 4.0 6 grand, or using more viscosity than needed.
 
TiRod said:
I have used Slick 50 to raise oil pressure - one bottle usually jumps it 15-25 pounds. The teflon apparently slows down the sling off from worn bearings, and works pretty well even when you let 5 quarts leak out and see the light on. It's been years and the pressure is still up, despite changes every 5k, which makes me wonder about the "re add" suggested every other change.
Click to expand...

TiRod,

I am no fan of Slick 50 ( I am just not in favor of putting flourine based compounds in a combustion device) but I am curious about your results. How many miles, months have you used it on the same engine and what was the original mileage when you started using it? What oil and viscosity are you using for the 5 K changes?

Who else has used Slick 50 with success, say for 100,000 miles or more on a used, older engine? Anyone?
 
I had just replaced the oil and filter and was wondering this

raypla said:
My XJ is having the same symptoms and I am going to replace the sending unit and this is all I could find http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=MPE&PartNumber=OP6185SB&Description=Oil+Pressure+Gauge+Switch

Is this it?
If not could someone send me a link. I thought everybody was saying this is a $10 item? This is the cheapest I could find it, that is at a local store. Advance auto and Autozone want something like $50:wierd:
Click to expand...
 
Anyone? :repair: I want to get this taken care of, I don't like seeing the oil pressure @ 0:tear:

raypla said:
My XJ is having the same symptoms and I am going to replace the sending unit and this is all I could find http://napaonline.com/masterpages/N...P6185SB&Description=Oil+Pressure+Gauge+Switch

Is this it?
If not could someone send me a link. I thought everybody was saying this is a $10 item? This is the cheapest I could find it, that is at a local store. Advance auto and Autozone want something like $50:wierd:
Click to expand...
 
I don't think your going to get an answer.

I bought mine from the local Autozone, they had it in stock. They should have it online as well. None us can verify (that I know of) what you are asking for from the limited details these online stores give. If you gave them the correct, year, make, model, engine, etc. and they offered that part to you then it should be OK.

I would go to a local auto parts store for this part, then you can look at it in person first and see if looks right. It is a very common stock part for most auto parts stores.

I don't recall what I paid at A-zone, but $50 seems about right. I don't recall anyone saying it was anywhere near a $10 item.

Have you checked the electrical connection on the end of the oil pressure sensor to see if it is loose, or dirty first!!!!
 
Yea I'll go take a closer look at it right now and I should be able too tell if it looks correct. I saw it at NAPA for 25$ give or take so if it's not the wire connection hopefully thats it.

Thanks for responding:yelclap:


I took a look and thats it :)
 
Last edited:
Oil pressure is back up there. The "switch" had oil coming out of it when I set it down. That switch, sensor was the problem:sunshine:

I could'nt of done it without NAXJA :repair:
Thanks,
Ray
 
My oil pressure is kinda scary sometimes too, I think.
Just did the rear main seal, checked all bearings, even had a retired mechanic friend check them and he was amazed at how good they were. Did the rear main seal, fixed all the leaks...for the first few days afterwards I had even higher pressure than I did previous, basically my oil pressure according to the dash gauge showed those of a brand new engine. It seems that since then, my oil pressure has slacked off a bit. It's still within spec as I seem to get around 18PSI at warm idle, and all sorts of readings within spec when at highway or city speeds.
I'm worried that my pressure will drop further and I'll have major problems. First things first will be to remove and replace the shitty fram filter that's in there tommorow. When I did an oil change my parts store ONLY had fram filters! when I asked for anything else the guy there looked at me like I was crazy and told me fram is the best quality there is. My dad has been running them in every car for years with no problems but the jeep seems pretty picky, so I'm goign to change it to something else just to be safe.
 
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