Hello i have a 1996 dodge ram 2500 4-4 5.9 when i come to a stop my oil pressure go's down than when i hit the gas it is fine is my oil pump going bad ? if so can it be changed with out lifting the morter out. TY

 

What kind of pressure are you getting? Remove the oil pan then remove and replace the pump. My first guess is that the pick-up screen on the pump is clogged or the sending unit is going bad. There is a free copy of the 2001 factory serice manual listed in the FAQ section of this site. It will explain the details.

 

holy crap,

mine started doing this last night, and i was just about to post looking for info on this.

for me.

pressure sits at around 1/2 of full pressure. it looks to be about 200, psi(?) when i stop it drops to 0 and the check guages light comes on and beeps, but on startup it goes away.

 

If your oil pressure sending unit is the original, I would start by replacing that. Check all your grounds, as well as the connection to the sender. See if the sending unit is leaking anywhere also.

I am pretty sure the sending unit uses a "special" socket.


Good luck.

 

I love diesel demons license plate. Makes me want diesel

 

I would look into getting a manual gauge to screw into where the stock sender goes, that way you know exactly what kind of pressure you have. I would think it should be at 25+ at idle. I know mine sits at like 35 when my truck is idling. Like was said before, your screen on your pump is probably just clogged up and at idle the pump isn't spinning fast enough to really suck the oil up.

 

Hopefully it is just the sending unit.
If the screen is clogged at the pump, then the timing chain is usually the culprit. So after changing the unit or using a manual gauge to verify the actual pressure and there is none. Will need to change the timing chain while switching the pump.

 

i replaced my Oil pump for the saem reason
i installed a High Volume, it is available as an option at Auto parts stores
i run about 40-45 psi idling.
about 60 driving.
Excellent.
but i fu have any existing leaks, they will get worse.

the worst part in doing the entire process was the gasket... that thing was huge, had to use ALOT of
permatex to hold it in place while trying to get the pan back up in there... *whew*[&:]

 

Couple questions and comments about the posts here.

How does a timing chain problem affect the oil pressure? Yes, while the camshaft does drive the oil pump, it does so on the 318 and 360 bat the same time it turns the distributor. When putting in the distributor you should have the slot in the pump aimed correctly per the manual. I think this is to allow the distributor to easily slide into the slot on top of the oil pump shaft and have the distribitor pointed correctly per the manual. This slot sits in the top of the gear that is turned by the camshaft. It in turn, drives both the distributor and oil pump at the same time. If the engine is running good otherwise, I would not think the timing chain would cause the oil pump to be affected.

When putting the pan gasket in place, take about 6 to 8 extra bolts the correct thread of the pan bolts and cut the heads off to make studs. Screw these loosely into the block evenly spaced around the pan. When you put the oil pan gasket up, push it over these studs and use some permatex on the threads to hold the gasket in place. It's only gotta hold for a minute or so. Lift the pan up and slide it over the studs. Insert your bolts in the other holes to hold the pan up and then remove the studs. I actually wrapped a little black tape around the studs I made to make the amount of permatex I need less. Works every time.

As a check before replacing the pump, I agree with silveram99 about removing the electrical sending unit and using a mechanical one to check your pressure. If the pressure still drops too low, you definitely need to replace the pump. XXL1500 was right to use a High Volume pump as a replacement. It'll extend the life of an older engine while not raising the pressure and causing possible seal problems. At the parts store they are only like $5 to $10 difference in price from the regular. Also if you have to replace the pump, buy a Melling oil pump you will not be sorry you did. Be very careful with getting the new pump inserted correctly onto the oil pump shaft and make sure it is fully seated before tightening the bolts. The cast metal pump will easily break if you have not taken those precautions. I've attached a photo of an oil pump that was not correctly inserted onto the oil pump shaft before being tightened. If you look closely you will see cracks all around the receiver for the input shaft and a crack in the cast oil pump casing around the cracked receiver. It is a good idea to change the screen, but if you can give it a good cleaning and it looks fully unclogged then go ahead and reuse it. be sure to fully clean the inside of the oil pan also to remove any gunk that may be there. Now is also a good time to give your oil pan a good coat or two of paint. Good insurance against a rusted out oil pan. Had that happen on my 91 Ford.

To take the sending unit out I remove my K&N CAI and use a crescent wrench to loosen it. Doesn't take much to loosen it then you can thread it the rest of the way out by hand.

Good luck

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Our stock timing chains have that fancy nylon coating they put on them to keep them quiet. So when the gears and chain start getting old those nylon pieces fall off and sit in the bottom of the oil pan and eventually will clog up the screen for the oil pump. That is part of the reason why timing chains are something that should be replaced after about 80k on our trucks, once that nylon flakes off then there is less tension in the chain. I am going to do my timing chain in the near future, but I want to change the cam and if I am going that far I want to do the intake and a fastman and so on lol. So right now I am trying to save the money to do it all at once. I have thought about running a gear drive instead of a timing chain too, I haven't looked that hard for one though. Does anyone know any real dis-advantages to a gear drive besides noise?