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darkman
Dodge Dakota
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12/01/2003
23:12:36
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 Subject: wierd low oil pressure 3.9l v6
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Message:
Heres one that has me stumped. I have a 94 Dakota with the 3.9 l v6. recently i've noticed that the oil pressure has been dropping, not at idle everything is fine then, as the engine revs the oil pressure starts to drop, not to critical levels but definitely noticable on the guage. This last weekend i was driving about 15 miles from my house climbing a three or four mile section of the freeway over a summit when I looked down and saw that my oil light was on and the guage was showing very low pressure I pulled over and checked the oil and it was topped out on the dipstick. when I restarted the truck the oil pressure was fine but I decided to turn around and try to get home. i noticed that if I kept the rpms low that the oil pressure would stay up and if I reved the engine by downshifting it would eventually drop and the light would come on. I could get the pressure back up by letting the engine idle with the clutch in but the pressure would drop again very quickly when I would let the clutch out and resume my speed. I stopped once for a few minutes and strarted again and had decent pressure all the way home. when I got home I decided to add a quart of oil even though it didn't need it. since then I have only driven it a little but the oil pressure is up where it was last year, 2/3 of the way across the guage running and just below center at idle. Its like the oil is going somewhere and not returning to the sump quickly enough. Anyone with any imput woulb greatly appreciated.
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Tim J
Dodge Dakota
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12/02/2003
02:20:35
| RE: wierd low oil pressure 3.9l v6
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Message:
Your oil pump is shot. Replace it. It's a known problem on the early Magnum sixers.
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FazDak
GenII
12/02/2003
09:47:19
| RE: wierd low oil pressure 3.9l v6
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Message:
Very well could be the pump but a few things to try first.
Replace oil filter. Make sure your oil level is no higher than the full line on the stick and if neither of those help try a new sending unit.
Good luck
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marty
Dodge Dakota
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12/02/2003
22:12:48
| RE: wierd low oil pressure 3.9l v6
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Message:
it might be the guage as well. CHeck ur oil pressure. The sending unit is right adjecent to ur distributor take it out and hook up a guage to it and see what it says. SHould be around 30-50 psi at idle. If its low then yes it is ur oil pump. If it's fine then it is the guage that is screwed up.
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darkman
Dodge Dakota
JOIN HERE
12/02/2003
23:06:37
| RE: wierd low oil pressure 3.9l v6
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Message:
Since I added a quart too much oil the problem has gone away, but I'm afraid I'm going to start blowing through the seals. my guess is that the higher oil in the pan is making the pump work a little easier. I've bought a high velocity oil pump and I'm going to replace it. I'll post the results when I'm done
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Darkman
Dodge Dakota
JOIN HERE
2/24/2004
19:49:39
|  RE: wierd low oil pressure 3.9l v6
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Message:
Well I finally got around to pulling the pan and here's what I found.
The oil pick up is shaped like the front of a horn with a screen across it's wide point,then on the bottom of the pan are three small dimples about 3/32 of an inch tall in the pan that keep the pickup from sitting tight on the bottom of the pan to allow oil to pass. What happened was that debris that looks like carbon built up on the bottom of the pan between the screen of the pickup . these particles were to big to get through the screen but light enough to be picked up by the incoming oil and clog the screen they would settle to the pan when the car was at idle but would get picked up and clog the screen at higher RPM's, when the car would go back to idle the debris would fall away and I would get pressure again. while the pan was off I replaced the oil pump with a Melling high velocity. disassembly of the old oil pump showed that it was in good condition. it would be nice if an oil pickup could be found like GM has on their small block chevys that has a releif in one side of the pickup to prevent this. To all thanks for your help.
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