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nicechad 11-08-2010 10:55 PM

Another oil pressure/ upper end noise problem
New to WF, just bought a '98 TJ to replace an 87 YJ I sold after owning for 13 yrs. New Jeep is a 4.0, 5spd, Sahara. Background of Jeep - I am 3rd owner, 94K, Previous owner has gone through the head to try to fix upper end tick. New valve springs and lifters that I know if, not sure what else he replaced. Has aftermarket header, looks to be welded in middle, exhaust cut after the cat, (need to put muffler on and rest of exhaust pipe). Homemade by PO generic cone intake filter. Airraid throttle body spacer. I bought it knowing it had the ticking/ knocking upper end issue and low oil pressure (confirmed with my harbor freight gauge at almost 10psi at idle and 30 at higher RPM) and will replace the motor if it comes to that, but hard to believe it is shot at 94K.

SO, I have rebuilt the stock oil pump, but did not replace the pickup tube. Pan looked clean. Changed filter from STP to WIX, added 5 qts of 10W30, and a quart of slick 50. Same issue. OK pressure at cold, as soon as oil is warm, pressure drops to almost nothing and engine has a loud tick/knock in what sounds like the upper end/valvetrain. Engine runs fine, temp good at 210. Just the upper end noise and low/no oil pressure. Replaced the sending unit. Same deal. Going to find a deal on a HV oil pump and pickup tube, and go from there. Is my line of thought correct here? I think that the 10 PSI is too low at idle and hopefully that is where the tick issue is stemming from. Ideas? Thanks!

nicechad 11-09-2010 12:21 AM

Found a deal with coupon code online for Melling HV pump at Advance Auto. Probably order it and the exhaust in the morning.

jasonwrangler 11-09-2010 12:59 AM

ahhhh money pit

nicechad 11-09-2010 10:50 AM

Not yet, I actually bought it cheap enough to rebuild or replace the 4.0, but not ready to do that just yet. I started it this morning to go to work, 40psi pressure, and at idle it sounds fine, reverse and back out of the driveway and the ticking/clacking knocking under load begins, even with good oil pressure. So I am holding off on the oil pump and put it in the pole barn to let a couple of friends listen to it tonight and see what advice I get.

rubicon hobby 11-10-2010 09:33 PM

Its the Cam bearings I have the exact same issue gonna replace the engine as soon as I can get the money together I replaced the Oil pump and All the rod bearings didn't help, same exact problem once the engine is warm I have 7 lbs of oil pressure at idle and 18lbs at hiway speed. The engines are very tight when new 001-003 oil clearance. The cam bearings wear and the pressure goes away. I am favoring the ATK reman engine 2200.00 plus install. Also the HV pump requires modifying the oil pan to make it fit its bigger than stock. and it wont fix it. Good Luck

rubicon hobby 11-10-2010 09:35 PM

The tick is probably the lifters starting to collapse from low oil pressure. I added Lucas oil stabilizer and that helped a little.

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