Oil pressure drop

4x4Dave · Jul 24, 2013

Okay so just recently my 99 dodge ram 1500 5.9 starts to bottom out to 0 oil pressure after giving it hard throttle for a while. For a while i thought it was just the oil pressure sending unit because it would go to 0 and then back up to normal. but recently it went to 0 and started to knock. so i immediately pulled over and shut it off. i turned it back on after a minute and had normal oil pressure and no knocks. so i drove home at normal highway speeds and it maintained oil pressure just fine. it only happens if i get on it. I have already ran seafoam in it and ran diesel fuel through it and put castol gtx and changed the oil filter in it but still it happens after gettting on it for a while. I took it to a mechanic and they said the oil pumps on these things never fail and if it had it wouldnt be driveable. Any input would be greatly appreciated.

jf5.9 · Jul 25, 2013

this exact same thing happened to me when I had a Dakota with a 3.9. I owned the truck for 21 days before the pump sludged up. When you get on it the pump is pulling more oil and therefore more sludge if you have any in the pan. I thought it was a bad oil pressure sensor when it first started turning the idiot light on but it ended up being a pump plugging up with sludge. A new oil pump and a weekend later the truck was good as new thanks to the synthetic oil change I gave it the day after I bought it.

Casper · Jul 25, 2013

4x4Dave said:
Okay so just recently my 99 dodge ram 1500 5.9 starts to bottom out to 0 oil pressure after giving it hard throttle for a while. For a while i thought it was just the oil pressure sending unit because it would go to 0 and then back up to normal. but recently it went to 0 and started to knock. so i immediately pulled over and shut it off. i turned it back on after a minute and had normal oil pressure and no knocks. so i drove home at normal highway speeds and it maintained oil pressure just fine. it only happens if i get on it. I have already ran seafoam in it and ran diesel fuel through it and put castol gtx and changed the oil filter in it but still it happens after gettting on it for a while. I took it to a mechanic and they said the oil pumps on these things never fail and if it had it wouldnt be driveable. Any input would be greatly appreciated.

You need to drop the pan and inspect the oil pump suction--probably should have a new oil pump on hand for installaton, as well as the pan gasket and etc.
This kind of sludging is more common in the 5.2L, but an older 5.9L can gunk up too.

Do it now or before long you'll have knocking at start up and begin burning oil as your rings wear. :Nonono:

4x4Dave · Jul 25, 2013

thanks guys yah that sounds about right im thinking its the pick up tube pulling in crud from the oil pan but in a 4x4 dropping the oil pan is alot of work. are there any alternatives?

jf5.9 · Jul 29, 2013

not really any alternatives to it - I have seen people drop down the front axle before lifting up the engine to get a pan off tho on a 4 x 4 . . . keep us in the loop with whats going on

4x4Dave · Jul 29, 2013

Will do thanks for the info!

Oil pressure drop

4x4Dave

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jf5.9

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Casper

U.S. Navy (Ret.)

4x4Dave

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jf5.9

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4x4Dave

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