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Discussion Starter · #1 ·
So i changed my oil yesterday. I have a 1999 SE 2.5L. I filled up 4 quarts of oil. When i started driving i saw that the oil pressure went to 80. I then checked the oil dipstick and it was too far over the safe area. I thought i was supposed to fill 4 quarts? Should i drain some out to the safe area?
 

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It does take 4 quarts, catch is, you'll never get all the old oil out. So adding 4 quarts plus whatever is left in the block and pan, will put you over the mark everytime. I would drain a little out of it until your back on the safe mark. Oil PSI that high for a long period of time will cause you valve cover gasket and your oil pan gaskets to seep oil. Not a good scenario.
 

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Did you change the filter?
 

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Discussion Starter · #5 ·
Yea i bought a new filter. So i just got done taking some of the oil out so that its now in the safe area. But the oil pressure is still at 80. Im thinking i damaged the sender unit while changing the filter
 

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It does take 4 quarts, catch is, you'll never get all the old oil out. So adding 4 quarts plus whatever is left in the block and pan, will put you over the mark everytime.
Unless the 2.5L engine is different from all other engines out there, of course draining the oil out from the pan drains the block and all the oil that is in the pan. Draining an automatic transmission doesn't get all of the ATF out but draining the oil from its pan drain plug will drain all of the engine oil out.
 

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I run a ph8a. With it and the fact that I let mine drain completely 5 Qts puts mine in the prosper range. If I'm not mistaken the actual capacity for the 2.5 is 4.5 Qts. The ph8a is double size of the stock filter.
 

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LouieDelTorchio said:
So i changed my oil yesterday. I have a 1999 SE 2.5L. I filled up 4 quarts of oil. When i started driving i saw that the oil pressure went to 80. I then checked the oil dipstick and it was too far over the safe area. I thought i was supposed to fill 4 quarts? Should i drain some out to the safe area?
Oil pressure is not affected by the amount of oil. If anything with too much oil it will cause a drop in pressure as the crank beats the oil and cause it to foam and slow the drain process. What can cause an increase of pressure might be the viscosity of oil u used or like you said the oil sensor. Question how old was the old oil? Does it go down after warm up?
 

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I run a ph8a. With it and the fact that I let mine drain completely 5 Qts puts mine in the prosper range. If I'm not mistaken the actual capacity for the 2.5 is 4.5 Qts. The ph8a is double size of the stock filter.
Factory manual says it's 4 quarts and that PH8A isn't adding an extra quart of capacity. Overfilling a crankcase can be as bad for the engine as underfilling it, I'd stick with what capacity the Jeep engineers say the 2.5L engine holds... 4 quarts and maybe .1 quart for that very slightly oversize filter.
 

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I will defer to your knowledge on the capacity of th 2.5. I agree too much oil is a bad situation for bbl the engine. It may not be true in all situations but in my jeep that filter and 5 Qts falls in the grided area of the dipstick.
 

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Discussion Starter · #13 ·
Ditchdoc said:
Oil pressure is not affected by the amount of oil. If anything with too much oil it will cause a drop in pressure as the crank beats the oil and cause it to foam and slow the drain process. What can cause an increase of pressure might be the viscosity of oil u used or like you said the oil sensor. Question how old was the old oil? Does it go down after warm up?
I did not know that. The old oil was about 7k miles. Its always at 80
 

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LouieDelTorchio said:
I did not know that. The old oil was about 7k miles. Its always at 80
What viscosity oil did you replace the old oil with. Got to remember too that old oil will be thinner therefore have lower pressure. High oil pressure is not really a bad thing unless it suddenly occurs this is a indication of blockage perhaps from the new filter. I will have to see what the oil pump relief is set at once I find my teck manual. I will also try to find test ports so if u can hook a wet gauge and test the different pressures. Just give me time ill help you out to the best of my ability.
 

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Discussion Starter · #15 ·
Ditchdoc said:
What viscosity oil did you replace the old oil with. Got to remember too that old oil will be thinner therefore have lower pressure. High oil pressure is not really a bad thing unless it suddenly occurs this is a indication of blockage perhaps from the new filter. I will have to see what the oil pump relief is set at once I find my teck manual. I will also try to find test ports so if u can hook a wet gauge and test the different pressures. Just give me time ill help you out to the best of my ability.
I got 10w30. Thanks for helping, im really not too smart with this stuff
 

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Have you put a mechanical gauge to it to see what the pressure is really running? That ought to steer you to or away from the stock pressure sender. I keep an aftermarket mechanical OP guage on hand (that I've tested to be accurate) and some various adapter fittings and tubing enough to do a temporary hook-up and stick it up on the windshield so I can read it while driving around the block or something.

There is a pressure relief valve in an engine oiling system that could be plugged up or jammed shut. It is typically a little spring loaded piston in a bore on or near the pump outlet (I don't know for sure about your Jeep) that limits high end pressure out of the pump to keep it from blowing the filter or some other problem. It is supposed to open gradually and dump excess oil back into the oil pan inside the engine when the oil is cold. and/or the engine RPM is high. This is not the same valve as the oil filter bypass valve that opens to bypass some oil around the oil filter element. The latter is usually built in to the oil filter itself...but not always.

Just some ideas.
 

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Just a thought, not sure on jeeps but on some of my chevys, if you remove the wire from the sending unit for the pressure gauge it will cause the the gauge to spike to the top.

Does the gauge move or is it stuck at 80?

Maybe you pulled the wire off when removing the filter....
 

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Louie, the oil pressure should change up and down as you rev the engine from idle to high and back to idle, if it does not, you may have a problem like Chris mentioned. Do like Blind Dog says, take the Jeep to a Mech and have the Oil Press. checked by a Mech with a known good gauge, that will solve your concern. Remember the fact that new oil many times will give you higher pressure readings because is new, oil tends to fall in viscosity as it gets contaminated with the combustion and friction from normal use.
 

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Johnnymoto said:
Louie, the oil pressure should change up and down as you rev the engine from idle to high and back to idle, if it does not, you may have a problem like Chris mentioned. Do like Blind Dog says, take the Jeep to a Mech and have the Oil Press. checked by a Mech with a known good gauge, that will solve your concern. Remember the fact that new oil many times will give you higher pressure readings because is new, oil tends to fall in viscosity as it gets contaminated with the combustion and friction from normal use.
My oil pressure stays pegged on 50 while driving and never drops below 40 at idle. It does sound to me like you damaged the sending unit. But most of the time a damaged sending unit will cause a "check gauges" light and it will display no pressure. I've never heard of one going to 80 if damaged. I would check the pcv valve on top of the valve cover to make sure it's not clogged or anything.
 
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