1999 - 3.9L No Oil pressure at warm idle - Dodge Durango Forum and Dodge Dakota Forums
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post #1 of Old 07-05-2011, 02:15 AM Thread Starter
Dust0800
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1999 - 3.9L No Oil pressure at warm idle

Hey guys,

Just bought a 1999 Dakota Sport, 3.9L. Got it on the road and after 15 minutes of driving the oil pressure Gage went from 40psi to 0 as I came to a stop sign. The truck had been sitting for a few months when I bought it and the oil is a nasty nasty dark color. (was already planning to do an oil change when I got home). I've heard to change/clean the oil pressure sender and do an engine flush however I am wondering if the truck is ok to drive. The oil pressure shoots back up to 40 when I'm on the gas and only drops when I brake for a corner etc.

Anyone else had this happen to them? Any tips to getting the sender off without buying the special socket?

Thanks, Dusty
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post #2 of Old 07-05-2011, 03:10 AM
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put a manual gauge on it before you do anything....it's possible pick-up screen could be plugged

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post #3 of Old 08-04-2011, 02:13 AM
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Oil pump and/or bearings are worn and the oil is too thin when warm to build pressure. Change the oil using a higher viscosity oil like 10w-40 and add a viscosity enhancing product like STP Oil Treatment.
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post #4 of Old 08-30-2011, 02:20 AM
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ive been having the same problem on my 97 3.9l. put a manual guage and it showed the same. dropped the pan to check the screen... nothin.. replaced the pump while i was there and im still havin the same problem. guess now ill have to try the higher viscosity oil
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post #5 of Old 08-30-2011, 02:40 AM
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Agree with the manual gauge. It may just be the sending unit.

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post #6 of Old 08-31-2011, 06:44 PM
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still nothin changed with the thicker oil... now what?
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post #7 of Old 08-31-2011, 07:00 PM
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Originally Posted by tommy_tow View Post
still nothin changed with the thicker oil... now what?
Why not just change the rod bearings only? To boost oil pressure?. Its bin-done before. Just match the size you have now install it with "stp" or asy-lube and let it idle for 30mim's then up to 2000rpm's 5-10mim's God bless and good luck.
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post #8 of Old 08-31-2011, 11:02 PM
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As mentioned before, but a manual gauge on it and see if it really is dropping pressure.

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post #9 of Old 09-13-2011, 02:38 AM
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Quote:
Originally Posted by Dust0800 View Post
Hey guys,

Just bought a 1999 Dakota Sport, 3.9L. Got it on the road and after 15 minutes of driving the oil pressure Gage went from 40psi to 0 as I came to a stop sign. The truck had been sitting for a few months when I bought it and the oil is a nasty nasty dark color. (was already planning to do an oil change when I got home). I've heard to change/clean the oil pressure sender and do an engine flush however I am wondering if the truck is ok to drive. The oil pressure shoots back up to 40 when I'm on the gas and only drops when I brake for a corner etc.

Anyone else had this happen to them? Any tips to getting the sender off without buying the special socket?

Thanks, Dusty


A lot depends on how many miles the engine has. If it's 100K or more, you may have worn bearings. Especially if the previous owner was slack about oil changes. Now, the original timing chains on a lot of Detroit iron had a plastic like coating so when you looked at it new, it was smooth as silk and quiet. The polymer gets old and comes apart. I've fished a bunch of this out of the oil pickup screen in the past.

Now is the time to check your engine's condition. What kind of shape is the timing chain in? If it's worn, replacing the timing chain will sometimes help a little. That could also be where the garbage in your pickup came from. While you have the pan down, replace the oil pump. You want a high VOLUME pump. This will compensate for worn bushings and bearings. DO NOT put a high pressure pump on it as it will blow your bearings out and shorten the life of your engine quick.

I'll bet a new pump will give you the 10 psi per 1000 rpm you need.
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