ok i have serched for 2 hours trying to find the root of my problem. here it goes. i have an 98 5.9 and 2 weeks ago i blew a radiator and in turn blew a head gasket. i have since replaced all top side gaskets (head, intake, valve pan, plenum, t-stat, ext.) the heads and valves, the radator or most hoses, and the cat. im sure i replaced other things just to manythings. ok i got all this done and the motor sounds great, strongest its ever been, one issue i have now is when it warms up and im driving along my oil pressure gauge goes to zero. ive replaced the oil pressure sending unit and it still does it. my question is could the water in my oil from blown heads mess up the pump. or could it be a blocked oil passage in the motor? im not sure where to go from here.

 

Contaminated oil may have toasted the pump, and/or the bearings. Don't drive it like that. Screw in a mechanical gauge, and verify that you are indeed losing pressure. (sometimes the gauge lies......) If you do indeed lose pressure, you can start by replacing the oil pump. (stock replacements are 25 bucks or so, I sprung for the high volume unit for 49 bucks.....) You can do this in your driveway in just a couple hours, with basic hand tools. You can also do the rear main seal, since you are going to be RIGHT there..... Mine wasn't leaking, but, I replaced it anyway.... (yeah, I just did this about two weeks ago..... in my driveway.)

 

Did you get a hardened drive shaft for the High Volume oil pump? It is highly recommended as I guess the stock shafts will snap trying to move the extra volume of oil.

 

No, I didn't..... I was not aware of that little tidbit. (that, and I REALLY didn't wanna yank the distributor.....) Guess I am going to be in there again soon eh?

Thank You.

 

I'm just throwing this out there, but here goes.

I had a 2000 Dodge Dakota that was showing no oil pressure when it was warmed up. It would drop straight to zero. I had my doubts that was actually going on as the lifters never rattled, etc. I swapped the oil pressure sender to no avail.

Turns out that I had an oil filter that failed. Took it off and the valving was completely stuck open. Put in a new filter and the oil pressure was the same as the day I bought the rig.

I can't mechanically explain what was going on, but I was happy for the quick fix.

 

thanks, i went ahead and changed the oil pump last night. and thanks for the hint on the rear main. i would have forgot about it. i had severl problems the pump went bad when sludge got into it and the strainer was completely blocked. i think that will take care of it. i am test driving it when i get off work so well see.

 

Let us know how it turns out.

 

well i cant tell you if it worked or not. i went home tried to start the truck and it just turns over. i dont know if i unpluged something or if something got wet. i left the hood slightly open like an idiot and it rained all day. so now i got that issue to work out

 

wow the truck just started fine. odd. but still no oil pressure. i think a mech gauage will solve this once and for all.

 

I would definitely put one on there to verify pressure. If the engine runs well, but, you STILL have no pressure with a NEW oil pump, time to yank the distributor, and see if the oil pump drive shaft hasn't broken. (depending on just WHERE it breaks, this may not be obvious from the oil pan side.....