about 3 yrs ago, i bought a '99 dodge ram with 100,300 miles. i have since put on an add'l 120,000. a year after buying it, i noticed the pressure dropped to zero on the guage. never made any noise, so i replaced the sending unit. that worked for awhile.
now, last year the pressure dropped again. i ignored it(thinking i need another sending unit). this time the motor started to clatter. so, i kept the RPM's low til i got home, and put in a new standard volume oil pump and pickup tube.
a few months after that, i pull the heads off(tracing a coolant loss), and find one of the heads is cracked. while i had the heads off, i noticed a lot of sludge on the lifter valley. i cleaned up as much as i could, and i guess some of it found its way to the oilpan and clogged the pickup screen. again, the pressure would drop to zero when at idle.
i changed the oil several times, using different thicknesses, and nothing seemed to help. so, i try some of that 5 min engine flush. well, i leave it in there for about a week. change the oil again, this time using sae40, and after installing a mech gauge, i have 4psi oil pressure at idle.
so, i dont have the time nor the $$ to rebuild the motor. i need a patch to get me by for a few more months. would a HV pump give me more pressure, or will it continue to still be low, due to possible bearing wear?
The HV pump should bring up the pressure, but likely it should have a set of rod and probably main bearings...
BTW a coolant leak will cause excessive sludge in the area of the leak... Had the same prob on a 250 I6 that was weeping coolant up the head bolts, into the valve cover...
I think that Lubro Moly MOS2 additive may be worth a try. My neighbour has a 80's 4.0 Cherokee. The next day after the oil change, cheap oil filter exploded and it lost all the oil. It happened close from his home, but it made some strange noises after filling it up with new oil. Oil pressure dropped near zero with gear engaged. Somebody said that filling it up with LM MOS2 additive may help and after adding 2 bottles, oil pressure is over zero and it doesn't make any noise. It runs this way from January and made about 4000 miles.
http://www.liqui-moly.com/liquimoly/produktdb.nsf/id/usa_2009.html
I heard that off-roaders are using MOS2 additive to finish rally even with spun bearing.
i wouldnt worry about it
my moms cherroke has the 318, its got 179k on it, nothing done to the motor. but it burns oil, well she ran it a good 800 miles past due oil change and I started to notice the oil pressure would be 0 at idle, so I figured it was time for a oil change since she never chekcs the level. Well i pull the drain plug, and to my horror, I drained only about a 1/8 of a quart out, and it had run like that for 2 weeks. Another time it blew the oil pressure sensor right out of the block, and puked all the oil out on the way home, then drove it with no oil to the shop
needless to say it has no knocks or clatters, just burns oil, has had another 8k put on it since then.
Cant kill the thing! and i beat the shiznit out of that thing when I used to drive it, off roading all the time, and would just peg the motor to redline in the mud, thing will not quit!!
sounds like your pickup is full of . we just rebuilt the motor in my teachers durango same deal... drop the pan and check her out.
the 1st 3 times i pulled the pan, yes. but the last time i pulled it, the screen was free of any sludge or crud.
i will probably do what TurboCoupe50 suggested, and replace the rod and main bearings. i can do that without pulling the motor. :D
might as well.
hell while you got her apart pull the valvecovers and dump some kerosine down there to clear the pushrods and oil valleys.
i gave everything a good scrubbing, when the heads were off. and like i stated above, i did the 5 min flush treatment, too. ive heard doing too much will eat the coating on bearings.
Quite common on the later 318's, hence the reason they've been phased out.....
well, i picked up my FREE shortblock today. :D its a 318 from a 98 durango. ill continue to drive the truck until this gets freshened up. im currently shopping around for rebuild kits, but will have to wait to see what the machine shop is gonna say it needs.
also, the guy gave me a mystery fuel pump. any clue what kind it is? no identifying marks.