Engine/Transmission (1994 - 1998) Oil Loss, Oil Pressure Fluctuation

[BlameCandida]

I recently got my truck back from my dad after letting him use it for a year. I saw the oil was low, so I changed the oil and filter. While driving it the past week, whenever I go to idle, the oil pressure drops to 0. Once I get back in gear and am moving, it quickly climbs back to just over 40. I've checked the oil daily since then, and there is the correct amount. I figured it might be a faulty sensor, and was getting ready to order a new one.

Today, I am driving across the state, and checked my oil when I stopped to fuel up. The dipstick is bone dry. I looked under the truck, and see oil dripping from the front drive shaft. Oil must have been overflowing from the drain tube and collecting there.


What's wrong and what do I need to do to fix it?

 

[BigPapa]

First, before replacing the sending unit, I would put a mechanical gauge on it and verify your oil pressure. There is a 1/8" pipe port on top of where the oil filter screws on.

After that I'd nail down where your oil leak is. From your description it could be the vacuum pump/power steering pump, oil pressure sending unit, valve cover, tappet cover, vent tube, gear case to block, gear case cover, or front crank seal. You'll need to get all the oil off first. It may only leak at higher RPM and under load so you may have to clean it off and go for a short drive and check it. Just bear in mind, the wind while driving will blow the oil and make it harder to find.

 

[GAmes]

My guess is the oil pressure sender failed, then burst while you were on the road. They are kind of difficult to get out due to the weird hex they have, so here is my recommendation for installing the new one and easier replacement in the future. They are 1/8 npt unless you have a post '98 block, then I think they have a different thread. At any rate find a straight through adapter that fits on the end of the new sender and screws into the block. It will be either 3/8 or 7/16. With the smaller wrench installing it and removing it in the future is much easier. Also, don't settle for a low priced sender from a box parts store, get a genuine Cummins. The after market ones fail, a lot.

 

[mwilson]

My guess is the oil pressure sender failed, then burst while you were on the road. They are kind of difficult to get out due to the weird hex they have, so here is my recommendation for installing the new one and easier replacement in the future. They are 1/8 npt unless you have a post '98 block, then I think they have a different thread. At any rate find a straight through adapter that fits on the end of the new sender and screws into the block. It will be either 3/8 or 7/16. With the smaller wrench installing it and removing it in the future is much easier. Also, don't settle for a low priced sender from a box parts store, get a genuine Cummins. The after market ones fail, a lot.

Yes to the above AND provide your Engine or Truck serial number so we can give you a sender part number that will read more or less correctly. Cummins for sure.....

 

[BlameCandida]

I need to get back to my tools before I can check the oil pressure or degrease the engine. But just from crawling all around underneath, it looks like all the oil is on the drivers side and front of the engine. The entire oil pan is oily, and that extends up about 2 inches from where it bolts to the engine. The starter is dry, and so is the area right behind the PS / vacuum pump where I think the oil pressure sending unit is. My engine number is 56393230

 

[mwilson]

There's an oil line that feeds the vacuum pump. Do you think that might have let go???

Generic picture, your ESN doesn't have a drawing attached to it for some reason...

 

[BlameCandida]

I parked the truck last night, and won't be driving it again until Sunday. I saw a little moisture at this tube coming of the intercooler.*

 

[GAmes]

That little tube is connected to the jiggle valve on the engine side. it vents air from the cooling system. The moisture is coolant.

 

[BlameCandida]

Last night I sprayed the engine all over with degreaser and let it dry overnight. This afternoon I got underneath with a roll of shop towels and wiped everything down, so I can spot any leaks. I topped off the oil.*




I went to fire up the truck, and it started very rough, and wouldn't stay on, even with me pushing the throttle. I waited a few minutes, and tried again with the same result. After that I figured I wouldn't try again, in case I make something worse.*

 

[BigPapa]

I saw a little moisture at this tube coming of the intercooler.*

What tube are you referring to? Nothing in your pic has anything to do with the intercooler.

"A" is the heater tube, "B" is the bypass hose Gary was referring to, and "C" is your upper radiator hose.

 

[BlameCandida]

It was that lower fitting on the bypass hose. Thanks.*

 

[Missouri Mule]

Your timing cover gasket could be leaking or the front seal on damper. After I did my kdp, dodge did not have the gasket for the timing case cover so I used sealant a couple years later I had oil on the oil pan and down the side of the driver's side engine. My Mechanic power washed the side of the engine. The oil leak was from the side of the timing case cover. New gasket fixed it,

 

[BlameCandida]

On further inspection this morning, I noticed that the vacuum line from the vacuum pump is broken. I hadn't noticed, since I wasn't using AC, cruise control, or 4wd since I got the truck back. So I guess the vacuum exhaust was increasing blowby, pulling oil with it?

 

[GAmes]

Plug the inlet or reattach the hose. If the engine is worn enough I can see the vacuum pump adding enough air to make the blowby excessive.

 

[BlameCandida]

I had a mechanic come out to look at the truck, and he says the injector pump failed. Is this related to the oil issue, or just separate bad luck?

 

[mwilson]

Did he go into any detail??? Plunger sticking??? Rare for a P pump to fail completely.

 

[BlameCandida]

No detail. I'll ask. I relayed the same information about my oil issues, and he checked for any engine codes. I told him I hadn't tried to start it since Tuesday night, since I was worried about breaking something worse, if something had broken in the engine.

He tried starting it, and it wasn't rough sounding like it was on Tuesday. It didn't catch though. He checked if fuel was coming from the FASS to the IP, and then checked if fuel was leaving the IP during cranking. At that position by he said it was an IP issue.*

 

[mwilson]

I assume he made sure the shut off solenoid was operating correctly???

 

[BlameCandida]

I assume he made sure the shut off solenoid was operating correctly???

Yep. Not an issue on my truck. I have mine running off a cable. We got under the hood and opened / shut it by hand too.*

 

[mwilson]

Ok, just had to ask......seen it before..