MJ oil pressure

Burley · Jun 8, 2005

I have an MJ with the 4 cylinder and manual transmission. The oil pressure reads about 17(psi?) when ideling. I replaced the valve cover gasket and the sending unit and neither has helped. is that normal?

Thanks guys.

Burley

RichP · Jun 8, 2005

17 is fine at idle, my 98XJ 4.0 runs 20 idle, hot, 45-50 at speed hot. Our two TJ's which are 2.5's run 20 idle hot and 60 at speed hot. Thats with 10W30 Mobil-1 and Mobil-1 filters in all.

Burley · Jun 8, 2005

Thanks Rich. Mine doesn't seem to go up much at all at speed when hot. Maybe around 24 or 25. Does that sound okay?

RichP · Jun 8, 2005

Burley said:
Thanks Rich. Mine doesn't seem to go up much at all at speed when hot. Maybe around 24 or 25. Does that sound okay?

Filter brand makes a big difference, if you have a fram on there replace it with a Mobil-1, K&N or Purolator Pure one and see if there is a change.

Eagle · Jun 8, 2005

Factory spec is 13 psi minimum at idle and 37 to 75 psi above 1600 RPM. Your idle pressure is within spec but the running pressure is a bit on the low side. Not horrible, but not great.

How many miles on the engine? What brand oil filter do you use? And what brand, type (synthetic or conventional) and weight (viscosity) of oil do you run?

Burley · Jun 9, 2005

Eagle said:
Factory spec is 13 psi minimum at idle and 37 to 75 psi above 1600 RPM. Your idle pressure is within spec but the running pressure is a bit on the low side. Not horrible, but not great.

How many miles on the engine? What brand oil filter do you use? And what brand, type (synthetic or conventional) and weight (viscosity) of oil do you run?

The odometer says about 138,000 but the body looks like 300,000! I am currently using a Fram with Castrol 10W-30 conventional. I just bought this truck about a month ago and did two oil changes about 300 miles apart because the new oil in the first change turned black right away. Do you think I should run a heavier weight oil?

Burley

Jeff in VA · Jun 9, 2005

I've been running Castrol 10/40 (conventional) with a Puralator for the last 50K or so in mine, and aside from some blowby and an ailing timing chain tensioner, all's been well. Got 160K on it now, and am aiming for 200K, before I pull the original 2.5 for a rebuild and throw in the "spare" motor I have compliments of Danno :wave:
Jeff

p.s. O/F changes every 3000 miles, whether it needs it or not

RichP · Jun 9, 2005

Burley said:
The odometer says about 138,000 but the body looks like 300,000! I am currently using a Fram with Castrol 10W-30 conventional. I just bought this truck about a month ago and did two oil changes about 300 miles apart because the new oil in the first change turned black right away. Do you think I should run a heavier weight oil?

Burley

NO, just a better filter...

Dr. Dyno · Jun 9, 2005

Burley said:
Thanks Rich. Mine doesn't seem to go up much at all at speed when hot. Maybe around 24 or 25. Does that sound okay?

No that definitely isn't good. It should be at least 37psi at speed. Try a different oil filter first; you could do a lot worse than the OEM Mopar filter. If that doesn't help, remove the oil pan and check the oil pump pick-up screen. If the engine's sludged up because the previous owner neglected the oil changes, you may find that the screen is clogged up. If that's the case, don't bother just removing the pump and cleaning the screen. Just replace the whole pump with a new one because at 138k miles, the old one will have seen better days anyway.

Eagle · Jun 10, 2005

Burley said:
The odometer says about 138,000 but the body looks like 300,000! I am currently using a Fram with Castrol 10W-30 conventional. I just bought this truck about a month ago and did two oil changes about 300 miles apart because the new oil in the first change turned black right away. Do you think I should run a heavier weight oil?

Burley

First -- dump the Fram filter. ASAP. Buy a Purolator.

Try either 15W50 synthetic oil or 20W50 conventional and see what that does for you.

MJ oil pressure

Burley

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Burley

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Eagle

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Burley

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Jeff in VA

<---respect

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