Oil Pressure Problem...

[87manche]

? Just out of curousity, why don't you want to use 20W-50 to get back lost oil pressure?

Oil pressure is oil pressure, if you had bad oil pressure with 10W-30 and 10W-40, but 20W-50 gets you good oil pressure, why would NOT want to use it?

Just putting off the inevitable I suppose. Using 20w50 to bring back the oil pressure on worn or damaged bearings may do even more damage to the motor in the long run. Fix it now and you might get away with a new pump and new bearings, disguise the problem and one day the pump might fail completely and the motor dies.

 

[Rootehound]

I will now.
The engine was out of a '91 owned by a friend of mine. He bought it in 1995. He had been using 5/30 synth-oil in it for years, so I just continued to do the same.

 

[Rootehound]

Just putting off the inevitable I suppose. Using 20w50 to bring back the oil pressure on worn or damaged bearings may do even more damage to the motor in the long run. Fix it now and you might get away with a new pump and new bearings, disguise the problem and one day the pump might fail completely and the motor dies.

You're right.
I'm just not looking forward to a weekend under the Jeep. Oh well.

 

[pikey77]

speaking of has anyone done bearings while the motors still in thejeep. I got a 2000 service manual and it shows how but just wondering if anyones actually done it.

 

[87manche]

my brother had done it in his. Said getting the oil pan off was difficult, I think he's about 4" of lift.

 

[WB9YZU]

? Just out of curousity, why don't you want to use 20W-50 to get back lost oil pressure?

Oil pressure is oil pressure, if you had bad oil pressure with 10W-30 and 10W-40, but 20W-50 gets you good oil pressure, why would NOT want to use it?

LOL! I was kidding!

I see where you're going, and let's see how far you will go down that path.
By your logic, you just continue to increase viscosity untill the problem is fixed, right?

Years back, there was a product called "Motor Honey" which was sold as a $2.00 engine rebuild. What it was actually, was a viscosity enhancer to fool you into thinking that you somehow fixed your engine because the oil pressure increased.
Many cars were sold with that in the crankcase. The customers thought they had a good engine based on the guage, but in actuallity had puchased a POS.
Same basic idea. No additional lubrication, just a higher number.

 

[Rootehound]

LOL! I was kidding!

I see where you're going, and let's see how far you will go down that path.
By your logic, you just continue to increase viscosity untill the problem is fixed, right?

No, what I was refering to was earlier posts that said it would be best to use a 10/30 or 10/40 instead of the 5/30 that's been used in the engine.

Once I do the bearings, I'll probably go with the heavier oil.

 

[8Mud]

Guess I'm going to have to go out to the garage and do it again. The formula has changed over the years, synthetic actually looks darker than it once did. But still seems to pour a whole lot faster than fossil (at the same viscosity **rating** and/or room temperature). Make your own test, I've made mine, doubt it's changed radically. I even tried it a various temperatures, there is a cross over point (temperature), where the synthetic retains higher viscosity than the fossil oil.
If you take a standard viscosity gage (funnel with a small hole) and the second hand of your watch and fill it full of fossil oil, time how long it takes to empty (not to the last drop) and do the same with a synthetic oil. I noticed the last time I did it, that the synthetic flows a whole lot faster than the fossil oil, at room temperature. Increasing the viscosity of the synthetic, may just be bringing the actual, as opposed to theoretic viscosity closer, into line with what the motor was likely designed to run with. A higher viscosity synthetic won't be a cure, but will likely raise the pressure a bit. And it's doubtfull it will hurt anything, oil viscosity recommendations are based on multiple factors, flow, adhesion, *drag* and other factors. The tendancy in recent times (the last twenty five years or so) is to reduce (viscosity) drag or HP loss from the oil and increase mileage (fractionally) as a priority.
Possible pressure loss, pump gears, paritaly blocked screen or pick up, pressure regulator in the pump, not sure but likely the filter bypass, bearing clearance, operating temp. of the motor (some are a little high 10 degrees does make a difference), viscosty of the oil, the gage itself, the sending unit and even the resisitance in the connectors. Possibly it's one, probably a combination. It's even possible, there is a partial oil restriction or excessive firction someplace, that is causing a little more heat as an average, high pressure at start up and low pressure at operating temperature. An oil temperature gage, also tells a story, the oil is also part of the cooling system.
They seem to have changed the formula for synthetic some, it used to adhere really well, oiling the top of the motor, was generally always good. Because even at temperature, the synthetic oil adhered better than fossil oil, and left a better residual coating on the parts. And actually retained it's viscosity better at higher temperatures.
But the formula does change, I have been using Castrol (10-40). The last batch made my pressures act up. This batch works just fine. I even went down and bought a two years supply (with the same batch stamp).

 

[urban_offroader]

speaking of has anyone done bearings while the motors still in thejeep. I got a 2000 service manual and it shows how but just wondering if anyones actually done it.

It's possible but not a fun job. To drop the pan on my '90 4x4 with 4.0 and no lift I put the front of the frame on stands and had to unbolt the shocks, roll bar, and sway bar. Then with the axle hanging as low as it could, I still had to force the pan to get it past the front differential and out of the way. I didn't need to remove the oil pickup though, as I've seen others say they did. As long as you've gone through that process you might as well change the oil pump, rear main seal, and at least the rod bearings, if not the mains too. It's a doable job, but it takes a lot of patience and at least a weekend if you've never done it before, especially if you want to check all the bearing clearances and do it right.

 

[Rick Anderson]

LOL! I was kidding!

I see where you're going, and let's see how far you will go down that path.
By your logic, you just continue to increase viscosity untill the problem is fixed, right?

Well, thats not exactly what I meant, but I see your point. BUT, 20W-50 is not that big of jump in viscousity and it depends on the oil pressure your getting with what viscousity.

So yea, if your getting 10 PSI @ 3000 RPM with 20W-50 and are considering running straight 50 weight race oil to bring it up a little more, to keep that motor running, I think we both agree, GIVE UP THE GHOST AND DO THE REBUILD.

But if your getting 10PSI @ idle and 25PSI @ 3000 RPM with 10W-40 and the oil doesn't water down with gasoline after 3k miles (a compression check may be in order), and the motor runs fair otherwise, I'd try 20W-50 and if it brought pressure up a bit toward what is closer to normal, I'd still run it.

But yea, 20W-50 is pretty much the end of the line, not only is it hard to find a thicker oil, I'd have to agree with you that your wasting your time on a shot motor if 20W-50 doesn't do the job.

 

[Rick Anderson]

But the formula does change, I have been using Castrol (10-40). The last batch made my pressures act up. This batch works just fine. I even went down and bought a two years supply (with the same batch stamp).

You don't mean Castrol Syntec? You know Castrol Syntec is NOT Synthetic Motor Oil, as almost everyone knows it.

Castrol was sued by Mobile about their labeling their Syntec as "Synthetic", Mobile lost because SAE has such a broad definition of "Synthetic" it was found that they were still covered. To add insult to injury, Castrol changed thier label to read "True Synthetic" after winning the case.

Mobil1 Synthetic is PAO base stock, manufactured by synthethising the molecues using pure gases in sophisticated chemical processes.

Castrol Syntec is Crude Oil base stock, ultra refined to remove all undesirable elements (like parafin) and then put thru a process called "Hydro-Cracking" where they cracked the hydrocarbon chains to an even length. The result is a very good conventional oil that is similar in molecular structure and properties of PAO base stock Synthetic Oil. The Hydro-Cracking process is what Castrol claims is their synthethising process, which the SAE definition is so broad it can't rule that out as a synthethising process.

Castrol Syntec is very close to good synthetic PAO oil like Mobil1, but the PAO synthetics are still better. So if your going to spend just as much, might as well get the better product.

The real Burn; when Castrol switched to the "hydro-cracking" process to make their new crude oil based oil that was a lot like synthetic, and called it synthetic, they bragged about how much money they were saving, because the process cost half as much as producing actual PAO oil. BUT CASTROL STILL SELLS THEIR SYNTEC AT THE SAME PRICE AS PAO BASED MOBIL1

 

[8Mud]

You don't mean Castrol Syntec? You know Castrol Syntec is NOT Synthetic Motor Oil, as almost everyone knows it.

Castrol was sued by Mobile about their labeling their Syntec as "Synthetic", Mobile lost because SAE has such a broad definition of "Synthetic" it was found that they were still covered. To add insult to injury, Castrol changed thier label to read "True Synthetic" after winning the case.

Mobil1 Synthetic is PAO base stock, manufactured by synthethising the molecues using pure gases in sophisticated chemical processes.

Castrol Syntec is Crude Oil base stock, ultra refined to remove all undesirable elements (like parafin) and then put thru a process called "Hydro-Cracking" where they cracked the hydrocarbon chains to an even length. The result is a very good conventional oil that is similar in molecular structure and properties of PAO base stock Synthetic Oil. The Hydro-Cracking process is what Castrol claims is their synthethising process, which the SAE definition is so broad it can't rule that out as a synthethising process.

Castrol Syntec is very close to good synthetic PAO oil like Mobil1, but the PAO synthetics are still better. So if your going to spend just as much, might as well get the better product.

The real Burn; when Castrol switched to the "hydro-cracking" process to make their new crude oil based oil that was a lot like synthetic, and called it synthetic, they bragged about how much money they were saving, because the process cost half as much as producing actual PAO oil. BUT CASTROL STILL SELLS THEIR SYNTEC AT THE SAME PRICE AS PAO BASED MOBIL1

True and I agree, I normally use Mobile 1 in my motors and buy bulk. I have a spare 4.0 in the garage, that has never had anything but Mobile 1 in it (after break in). My pickup which has never seen anything but Mobile 1 (180,000, mostly high speed driving with near zero ridge in the cylinders walls) and the wifes 95 XJ Mobile 1. And the lawn mowers, the wood chipper, the log splitter and other things Mobile 1 (though other high end products may be as good or nearly so, maybe better). My (used) 88 XJ has had the bottom and top cleaned out, everything else still has build up (the Castrol is good enough, on sale, 6 quarts for $15, a highly refined fossil oil). Castrol is good at offering choices, Syntec, half Syntec, ad nausium.
I also have various top off cans of Mobile 1 around, some dating from the late 80`s. There is a difference. I've compared. Some of the old stuff, seems better than the new stuff, looks different, feels different, smells different, adherse different and flows different. My scientific methode (I rub it between my fingers, look at a drop on a window pane, sniff it and maybe try to light it) tells me it's likely not the same stuff (reminds me of the old joke about how to tell if it's dog poop or not). I've had my hands in a whole bunch of industrial gear boxes and pumps. And a fair number of internal combustion motors. I like synthetic, because it shears less, important for gear boxes and doesn't turn to solids and gunk till a much higher temperature and some other positive properites (it's generally cleaner).
Some manufacutrers have a nasty habit of producing a good product, promotoing it, gaining a reputation (market share) and then slowly cutting back on the processing and additives, to make more profit. The regular burger of today, is the Jumbo burger of yesterday, which has been replaced by the Gigantic burger (at a higher price), which is actually the same size as the Jumbo burger used to be.
I may change to Valvoline, if I find a sale.
I think the point of the thread was oil pressure, then viscosity. My point was viscosity (adhesion, additives etc.), in a Synthetic as opposed to a fossil oil and even (it seems) to different batches of the both. Appears to be somewhat subjective. A slightly higher viscosity of synthetic, may help center the oil pressure gauge a little better. Or even a good fossil oil.
The oil pressure in my tired old 88 (never has been below the, for me, 15 PSI minimum at idle), runs a little right of center when cold and a little left of center when warm, Castrol 10-40 fossil (this batch), last batch ran a little too high a pressure and the motor was louder? The oil pressure ran a little lower with Mobile 1 (10-40), it ran a little lower when I had some cooling issues, it ran a little lower before I changed out the connecting rod bearing sleeves (the reason I actully changed to Castrol, for the break in and a quick oil change). I also screwed something up and the rear main is leaking, it pains me to add Synthetic oil to a leaky motor.:sad1:

 

[pikey77]

Im sitting with about 30PSI at 2000 RPM with 20w-50 and about 10-13 at idle. I was considering pulling the pan to replace the oil pump and figured if the bearings aren't that much more work replace them while I'm down there. I figure its a full weekend worth of work but Ill hopefully be doing a lift/new shocks then too so if im gonna get dirty might as well get real dirty. I've never had any knocking but am hearing allot of valve train noise.

 

[Dr. Dyno]

Im sitting with about 30PSI at 2000 RPM with 20w-50 and about 10-13 at idle.

Since the oil pressures are still below spec even with the thickest oil available, it's definitely time to replace the oil pump and main/rod bearings. If you wait until you hear a bottom end knock, it'll be too late and you'll be looking at a costly engine rebuild.

 

[GreenbeltXJ]

how long is too long?

 

[Rick Anderson]

Since the oil pressures are still below spec even with the thickest oil available, it's definitely time to replace the oil pump and main/rod bearings. If you wait until you hear a bottom end knock, it'll be too late and you'll be looking at a costly engine rebuild.

Just to add,

if you wait until you get bottom end knock, thats the crank scraping the bearings, that will damage the main journals on the crank, then it will either have to be turned down or even may have to be replaced, that makes the engine rebuild cost even more.

 

[Rick Anderson]

how long is too long?

A devestating earthquake will eventually hit San Fransico, all the experts agree, but when?

Same thing as a devestating earthquake in San Fransico, a motor with very low oil pressure will eventually eat itself up, when? It could be tomorrow, it could be 50k miles from now, no one can predict it to the mile with any certainty.

Only thing people will agree on for a prediction, Sooner is far more likely than Later.

 

[xjbubba]

Worn cam bearings significantly effect oil pressure. If it were me, I'd rebuild the engine while rebuilding can be done without major component replacement. If you wait for more noise than you have, repair could be very expensive, or not feasible. I don't think you can replace the rear main bearings (upper and lower half-bearings) with the tranny still in place. You'd be better off pulling the engine and doing it right.

 

[Dr. Dyno]

don't think you can replace the rear main bearings (upper and lower half-bearings) with the tranny still in place.

You can, and you can also replace the rear main seal. All you have to do is remove the oil pan and the rear main cap.

a motor with very low oil pressure will eventually eat itself up, when? It could be tomorrow, it could be 50k miles from now

A motor with a very low oil pressure will eat itself up prretty quickly. It definitely won't go another 50k miles; maybe 5k miles if you're lucky.