driving to the dump today, my oil pressure gauge dropped all the way to the L, then bounced back up to normal. i kept an eye on it the rest of the way there, and it kept dropping to the L, then back to the normal, sometimes hanging at the L for a second or two.
when i got off the freeway, it kept doing the same thing, and i noticed my truck sounded almost exactly like a diesel.
checked the oil level and checked for any obvious issues under the hood, but everything looked OK, other than the noise and the wonky oil pressure.
drove perfectly fine yesterday, no signs of trouble.

the needle seemed to drop when i hit the gas, and return after a pause or after i let off the gas, but it also seemed better up and down hills.

here's everything that has changed recently:
new oil cap yesterday,
topped off oil yesterday, it read a quart low, i added a quart,
got gas at costco (regular 87)

oil and filter were changed about 500 miles ago with mobil 1 10w30, i did a seafoam treatment about 200 miles ago. it has a new fuel filter, cap, rotor, and coil, all within about 500 miles. also set the timing to 10*


i do know i have an exhaust leak and that leaks can sound all kinds of odd, but i cant see it changing that much overnight.

any help is appreciated, this is my daily driver, so i need to figure this out quick.

 

Trash in pick-up screen.

 

X2

Put a new pump in it too while your at it. What engine is in the truck?

 

Its got the 5.8, and it has a relatively new oil pump, I believe.
so for crap in the screen i need to drop the pan, pull the pump and inlet, clean the inlet and screen, and reassemble?

does this likely relate to the noise, too? just underlubricated parts or is something more sinister going on?

 

The noise is from the lifters losing pressure and not staying pumped up. They're hydraulic in nature and require ~7psi of oil pressure to stay up. If you're going to pull the pan, put in a NEW pump. It's less than $20 and cheap insurance. I think I'd REPLACE the pickup tube assembly as well as there's no guarantee that cleaning the screen won't dislodge something else and do more damage.

 

line of questions part two:
first, oreilly has a cork gasket kit or a rubber gasket available for the oil pan. my gut says go rubber, but i figured i'd check with you folks.

second, the haynes manual says to remove the oil pan that i'll have to jack up the engine, and to do that they say to remove the radiator and upper intake manifold. that all seems a little excessive. looking at i the pan i think i could shimmy it out if i just removed or even shifted the downpipe a little, but i was wondering if anyone had any firsthand experience trying it that way. obviously, i can't tell how much clearance i'll need for the crankshaft counterweights and oil pump, so i will definitely lift the engine if that's what everyone here says, since that would be easier than having to do it all twice.

 

Go for the rubber ones. The cork ones will eventually dry up and start leaking.

The reason you have to jack up the engine is because the oil pump pickup hangs down so low.

It's not too big of a deal. Remove the engine mount bolts, and jack it up. Might be a good idea to put a bar across the fenders and run a chain from the bar to a lift ear on the engine to hold it up for safety. You may have to loosen the transmission mounting bolts as well.

 

Pick up the rubber gasket and make sure it has built in torque limiters (steel rings around bolt holes). It is possible to replace the pump without pulling the engine, but it is extremely tight. Lift the engine up and have fun!

 

My opinion: I would pull codes. This problem could be a few other things outside of the oil pump.

Which engine? How many miles? What was the temperature showing?

If it is the oil pump and you have the V8 (either one then If it were me, I would take off the intake manifold. When raising the engine the intake manifold goes towards the firewall. It limits how high you can lift the engine. And you won't be able to get the engine high enough to pull the oil pan. There will be enough clearance to fit your hand and maybe part of your wrist into the oil pan, but not enough to change the pump. (That darn riveted crossmember!!)I would also remove the radiator. It's quick and easy. Having it out of the way makes a huge difference and you can work unimpeded without worrying about damaging the radiator. You will need to remove the exhaust pipe from the exhaust manifold. So be sure to have a breaker bar! You'll need a breaker bar anyway to remove the motor mount bolts.

This is the way I would do it on a v8. I know others will say you can work with the clearance by dropping the pan and not totally removing it without taking off the intake manifold or disconnecting exhaust. I can tell you from experience, I can't. And I'm don't have big arms. I can remove the pick up tube and screen and change the oil pan gasket. But not get to the oil pump unless the pan is all the way out. It is so much easier having the pan completely removed. It will be quicker and you can do a better job. By just dropping the pan, crud will drop into the pan; you'll drop tools into the pan and have to retrieve them. My way, you can flush your cooling system and having a new intake manifold gasket.

Only other way is to grind off the rivets from the crossmember under the oil pan then reattach with bolts. But, I think that may take even longer, and there are several of these rivets. Did I mention that when I take over the world: I'm banning the use of rivets unless absolutely necessary!!!!

Forget to mention, the pick tube/screen assembly is attached using a gasket.

And yes, get the rubber oil pan gasket.

 

sorry, thought i'd gotten the engine and mileage in my signature, but it doesn't look like i did...

anyway, it's the 5.8l with 189k on it.
all other guages read normal at the time. kept a close eye on them all the way home.
i'll pull codes after i get home from work tomorrow.

and thanks for the advice, i'll definitely be jacking up the engine and going with the rubber gasket.

 

Getting rid of those rivets sounds tempting...
Is that cross member just to tie the rails together?

 

quick update:
got the pan out, had to remove the intake maifold and the radiator shroud, but not the radiator itself, and pull the exhaust off it's hangers.

There definitely was crap in the pickup screen, but the pump looks fine. going to have my hand at cleaning the pickup, but if i can't get it looking pristine i'll buy a replacement tomorrow.

i would like to day that there is a special place in hell for whoever put a cork gasket in this truck. the crap in the pickup looks and feels like cork, and the gasket (which was leaking) is a major PITA to clean off.

 

Are you saying the diesel sound is not knocking rods? Because that's what I always think of when I hear diesels, sounds like a few rods knocking....which makes sense with your low oil pressure story. I'm thinking putting some heavy weight oil or some special anti rod knock stuff in there?

Lifters make a ticking noise. Especially when starting up on high mileage engines. Rods knocking sound like 2 hammers hitting each other... cause that's basically what's happening, metal slamming into metal.

 

anyone else dropping the pan might look into using these from felpro. they made putting the oil pan on so much easier. i'd never heard of them, but they were included with my gasket, so i gave them a try.

basically, you screw them where the oil pan screws would go at the corners, then snap the gasket over them, then the oil pan itself, crew in all the pan screws other than where the snap ups are, remove the smap ups and install those 4 screws as well. saves you holding the pan up while positioning the gasket and trying to screw int he pan screws at the same time. brilliant.