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Low oil pressure after rebuild
https://slantsix.org/forum/viewtopic.php?t=53001
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Author:  moparlewellen [ Fri Aug 09, 2013 2:41 pm ]
Post subject:  Low oil pressure after rebuild

I rebuilt the slant six in my 71 dart about 4 weeks ago(rod/main bearings, rings, comp cam). I got it in and running really good for about 3 weeks until the oil pressure light came on while at idle (under 1700 rpm). I had recently had problems with my carb flooding a lot, so i took a whiff of the oil and it smelled like gas. So i replaced it thinking it was just thin. That didnt fix the problem. I then installed a manual oil gauge thinking it was the sending unit, but the oil pressure is so low it will not push oil up the nylon tube. So im wondering if i need a new oil pump, check the screen. Or is it something more serious? I don't know where to go on this. Any thoughts?

Author:  Reed [ Fri Aug 09, 2013 3:04 pm ]
Post subject: 

You you checked your fuel pump output? On a slant six the fuel pump diaphragm can rupture and let gas leak into the crankcase thereby diluting the oil. Fuel should never get into the oil, and if your oil smells like gas in a slant six the usual culprit is the fuel pump diaphragm.

Author:  moparlewellen [ Fri Aug 09, 2013 5:12 pm ]
Post subject:  Fuel pump

The fuel pump is brand new. I also flooded the engine really bad about a dozen times. So it got past the rings.

Author:  Doc [ Fri Aug 09, 2013 5:51 pm ]
Post subject: 

Cut your oil filter open and inspect for bearing material...
No metal in the filter, check for a stuck open oil pump releif valve.
DD

Author:  moparlewellen [ Fri Aug 09, 2013 6:39 pm ]
Post subject:  relief valve

Wouldn't the relief valve dump oil?

Author:  moparlewellen [ Fri Aug 09, 2013 6:41 pm ]
Post subject: 

The engine runs smooth with no bearing noise too.

Author:  75valiant [ Sun Aug 11, 2013 1:15 pm ]
Post subject: 

just because the fuel pump is new does not mean you don't have a bad diaphragm. gas in the oil is deadly. did your oil level go past full on the dipstick? that means fuel in the oil if so.

once you eliminate possible fuel contamination as the culprit, i would suspect the oil pump. i don't know if the slant six has a reed valve for pressure like the ford 302 does, but if it does that can definitely be the problem. has the engine backfired? that can blow out the reed valve, like a "water hammer".

there is a high chance you have one of these two problems. DON'T drive the car until you figure it out, you don't want to ruin your beautiful new engine.

i recently had a similar problem, detailed on the "idiot light" thread. i got lucky. all i needed was a new filter, and this was right after a fresh oil change! i hear the sending unit can be a bear to get out if you break it. good luck!

Author:  moparlewellen [ Sun Aug 11, 2013 3:22 pm ]
Post subject:  oil pump

I replaced the oil pump this morning. It must of fixed the problem because im running 40 psi at 900 rpm. The old pump was real hard to turn and made a clicking noise. I also filtered the old oil and cut open the filter and found no metal.
It runs like butter now.

Author:  ValiantBoyWonder [ Sun Aug 11, 2013 4:30 pm ]
Post subject: 

Glad to hear you got it going. Fuel pumps for our cars sometimes sit on stock room shelves for a number of years, rubber inside dries out and cracks. I never expect fuel pumps and vac cans to work on the first try. I work as a mechanic and when we get a new pump in we hook up some lines and test them with fresh gas. Even then, I've had breather valves spill gas. Its just a part of owning an old car.

Author:  Rug_Trucker [ Sun Aug 11, 2013 7:39 pm ]
Post subject: 

Did you used the same brand filter both times?

Author:  moparlewellen [ Mon Aug 12, 2013 8:03 am ]
Post subject:  filter

I used a microguard the first time and a fram the second

Author:  Joshie225 [ Mon Aug 12, 2013 2:53 pm ]
Post subject:  Re: filter

Quote:
I used a microguard the first time and a fram the second
Well, both brands are just above junk. Purolator is fair. Wix and Napa Gold are the best with wide availability.

Author:  moparlewellen [ Mon Aug 12, 2013 4:18 pm ]
Post subject:  filter

I dont believe there is a bit of difference between the $15 filter and the $3. I think that they are all junk, and I might as well save my self $12.

Author:  Reed [ Mon Aug 12, 2013 4:43 pm ]
Post subject:  Re: filter

Quote:
I dont believe there is a bit of difference between the $15 filter and the $3. I think that they are all junk, and I might as well save my self $12.
Then you haven't looked at the extensive testing and verification done by private individuals that demonstrate that there is a marked difference in assembly and materials quality on the market. Fram has been proven to be shoddily made junk.

Author:  crater [ Mon Aug 12, 2013 6:31 pm ]
Post subject:  Re: filter

Quote:
I dont believe there is a bit of difference between the $15 filter and the $3. I think that they are all junk, and I might as well save my self $12.
I think when your motor is running well and clean you probably don't need to be as concerned with it, but if I were trying to get some cleaning action going I'd want a really good filter at least 2 or 3 times to make sure nothing I'm trying to clean out of the engine gets past it.

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