3.9 oil pressure issues
#11
The cross member and very bottom of the trans.
#12
I've desludged several vehicles with Diesel fuel before. just drain all the oil out and fill it with diesel instead. Start the engine for 30 seconds or so. Then let it sit for a bit and do it again. As long as you don't let it run for more than a minute or so it wont hurt the engine. It might take a few times but it will pour out black sludgy stuff when you drain it. The other thing that works well is a mixture of oil and kerosene. I always throw a quart of automatic transmission fluid in my oil about 100 miles before I change my oil on my Dakota as preventative maintenance. I've seen sludge do very bad things to engines.
#13
#14
#15
#16
i have a similar problem.... but with a weird way.... i only have this problem every 5 000km. when i am due for my oil change and i will drive down a road and when i stop or turn it will go to zero and the *check guages* sign comes on and it goes back to normal.... kind of wondering if this is the same problem when the oil gets older in the engine?......
#17
This problem is all over the forums... my 97 3.9 does the exact same thing. I haven't fixed it yet, but i have driven the truck for about 100xxx mi. I'm planning the fix for memorial day weekend. I've done my homework for 5 years... so i don't really KNOW what im talking about... but i think i have a good understanding of the situation.
Magnums have a plenum pan on the bottom of the intake manifold... it's crappy gasket is the cause of all the problems. If you take off your air hat and open the throttle (make sure the engine is off when you do this...) and look into the throttle body... you will see oil. Lots of it. If it isn't happening yet, you will end up burning oil like saddam hussein. The sludgy remains of the burnt oil builds up in the engine and eventually makes it back to the oil pan where it clogs up the screen. It will drop your oil pressure more often and at higher rpm's if you run low on oil, or the filter gets clogged and it destroys various seals on its way, including the valve covers. It only really holds about 4.5 qts of oil, so it doesnt much to burn off enough to starve the oil pump... killing it in the process.
To treat the problem in the short term, make sure you maintain the propper amount of oil... check it every time you get gas. I've cleaned mine out w/diesel once... kept the oil pressure up for about 2000 miles, then back to the same ole same ole.
In the long term, the gaskets and seals of the intake, throttle body, oil pan, and cylinder heads , need to be changed. Personally, im not going to change the head gaskets this go round, im just gonna make sure the head bolts are torqued to spec... but i suspect i will probably be revisiting the cylinder heads next year.
THE GOOD NEWS: you dont have to pull the engine! You dont have to disconnect the a/c lines! You dont have to eff with the power steering or the brakes! The bad news: if you take it to a shop, it will cost you more than what you could get a different vehicle of the same caliber.
If you want to keep your truck, your best bet is to research what im telling you, buy yourself a good service manual (i like chiltons... many people disagree with me), and learn how to fix it yourself. You will find once you dig in that you are very lucky to have the vehicle you have because, once you get the fan off, there is enough room to literally stand inside the engine compartment (which will come in handy when your knees start to hurt).
In the mean time, it is not a death sentence as long as you treat the symptoms until you can get to the problem. Im hoping to make a youtube video when i do mine... if i do ill post it in this thread.
Best of luck... and tell your dad to have patients... dodges are trucks for people who like to work on trucks if you look at that one way, it's bad, but if you look at it another way, its an oppertunity.
Magnums have a plenum pan on the bottom of the intake manifold... it's crappy gasket is the cause of all the problems. If you take off your air hat and open the throttle (make sure the engine is off when you do this...) and look into the throttle body... you will see oil. Lots of it. If it isn't happening yet, you will end up burning oil like saddam hussein. The sludgy remains of the burnt oil builds up in the engine and eventually makes it back to the oil pan where it clogs up the screen. It will drop your oil pressure more often and at higher rpm's if you run low on oil, or the filter gets clogged and it destroys various seals on its way, including the valve covers. It only really holds about 4.5 qts of oil, so it doesnt much to burn off enough to starve the oil pump... killing it in the process.
To treat the problem in the short term, make sure you maintain the propper amount of oil... check it every time you get gas. I've cleaned mine out w/diesel once... kept the oil pressure up for about 2000 miles, then back to the same ole same ole.
In the long term, the gaskets and seals of the intake, throttle body, oil pan, and cylinder heads , need to be changed. Personally, im not going to change the head gaskets this go round, im just gonna make sure the head bolts are torqued to spec... but i suspect i will probably be revisiting the cylinder heads next year.
THE GOOD NEWS: you dont have to pull the engine! You dont have to disconnect the a/c lines! You dont have to eff with the power steering or the brakes! The bad news: if you take it to a shop, it will cost you more than what you could get a different vehicle of the same caliber.
If you want to keep your truck, your best bet is to research what im telling you, buy yourself a good service manual (i like chiltons... many people disagree with me), and learn how to fix it yourself. You will find once you dig in that you are very lucky to have the vehicle you have because, once you get the fan off, there is enough room to literally stand inside the engine compartment (which will come in handy when your knees start to hurt).
In the mean time, it is not a death sentence as long as you treat the symptoms until you can get to the problem. Im hoping to make a youtube video when i do mine... if i do ill post it in this thread.
Best of luck... and tell your dad to have patients... dodges are trucks for people who like to work on trucks if you look at that one way, it's bad, but if you look at it another way, its an oppertunity.
#18
the plenum is definitely one of the problems..i dont think it's THE direct contributor, but it doesn't help.
The motor holds exactly 1 gallon of oil. If you figure 1 quart in the filter and a half quart on top of each head, leaves 2 quarts in the pan. If you're a half or full quart low.....
I havent done it myself, but the intake supposedly comes off real easy if you leave the fuel system attached, and just unhook the main fuel line.
The head gaskets should last a long time on a street motor. But the intake gaskets and plenum are a replace item.
I agree on the room when you remove the fan...when i wrecked mine, that extra 7" of room for stuff to fold up saved me alot of $$ in parts I would have had to replace.
The motor holds exactly 1 gallon of oil. If you figure 1 quart in the filter and a half quart on top of each head, leaves 2 quarts in the pan. If you're a half or full quart low.....
I havent done it myself, but the intake supposedly comes off real easy if you leave the fuel system attached, and just unhook the main fuel line.
The head gaskets should last a long time on a street motor. But the intake gaskets and plenum are a replace item.
I agree on the room when you remove the fan...when i wrecked mine, that extra 7" of room for stuff to fold up saved me alot of $$ in parts I would have had to replace.
#19
#20
OK, i havent been on here in a while, but, what magnethead and DouglasWillard19 said is accurate, the plenum is definatly a contributing factor, over the winter, serving a license suspension, i decided to rebuild my 00 DAK with the 3.9L. i tore it apart, cab off frame, everything. when i pulled the motor, it had a ticking, but it wasnt anything associated with the head. but none the less i replaced EVERY gasket, even front and rear main seals. when i pulled the plenum pan gasket, it was thinner than paper.
in relation to the REPAIR MANUAL, there is one on here in PDF format as a sticky, https://dodgeforum.com/forum/2nd-gen...-download.html
the motors between 99 and 00 didnt change, so if you cant FIND a 99 only manual, the 2000 Manual on here will work. and it covers all motors and transmissions that were optioned for our trucks.
if you have any qustions regarding the 3.9L motor, dont hesitate to PM me, i have torn into this thing from frame up, and every system. i will admit i did receive help from members on here. but i am extremely familiar with the 2nd gen trucks equipped with a 3.9L, as well as the 5.9L motor.
also i do have a website for my trucks rebuild that also hosts the Factory Service Manual. as well as pics, and write ups. it is a work in progress, so if it isnt there PM me, and i will help you that way.
well thats my $.02, happy wrenching.
and dont hesitate to ask, its better to ask and seek help than to **** up and break something.. trust me i learned that the hard way.
my website ---> http://www.mydakotabuild.com
in relation to the REPAIR MANUAL, there is one on here in PDF format as a sticky, https://dodgeforum.com/forum/2nd-gen...-download.html
the motors between 99 and 00 didnt change, so if you cant FIND a 99 only manual, the 2000 Manual on here will work. and it covers all motors and transmissions that were optioned for our trucks.
if you have any qustions regarding the 3.9L motor, dont hesitate to PM me, i have torn into this thing from frame up, and every system. i will admit i did receive help from members on here. but i am extremely familiar with the 2nd gen trucks equipped with a 3.9L, as well as the 5.9L motor.
also i do have a website for my trucks rebuild that also hosts the Factory Service Manual. as well as pics, and write ups. it is a work in progress, so if it isnt there PM me, and i will help you that way.
well thats my $.02, happy wrenching.
and dont hesitate to ask, its better to ask and seek help than to **** up and break something.. trust me i learned that the hard way.
my website ---> http://www.mydakotabuild.com