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Discussion Starter · #1 ·
A while back, I asked for suggestions to help my low oil pressure. I was running 10W-30 Mobile One and most suggested I try a 20W-50. I did with Royal Purple Synthetic. It helped the oil pressure some but I started getting lifter tapping so I changed back to the 10-30 and it disapeared.

Now let me give you some other info on this engine. It is a 73 429-4bbl with supposedly low mileage. Compression check had every cylinder between 135 and 140 lbs. so I did not rebuild. Put in rear main seal, all freeze plugs and a rebuilt oil pump (which was probably a mistake) and cleaned screen.
I don't know what kind of oil pressure it had previously. Put in Mobile One 10W30. Shows 65 lbs at cold start up. Hot idle shows 0-5 lbs on mechanical Sun gauge. Runnin at 1500-2500 RPMs shows 18-20 lbs. No engine noise-motor runs fine but I don't want to tear this engine up for something stupid I have done. Only noise was noted above when I put the 20W-50 in it.
Now what do I need to do to try to solve this before I tear the engine down? I don't think 10-30 dino oil will make a difference, wts being the same.
I'm thinking maybe the first thing should be to put in a new Melling high vloume oil pump, tube and screen. The oil I put in the engine does seem to become dirty in a very short period of time.
Any other suggestions guys? Thanks
 

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I would take the pan off , check all the bearings and install a new regular pump. Sounds like loose mains to me. You might take a valve cover off and check the flow to the top of the engine.
 

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If you're going to pull the pan and swap the pump, go ahead and pull a main cap off and look at the bearing for any undue wear. If it looks OK plastigage it as well.
 

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Good advice so far.

If you have the pan off, check a couple rods and main bearings.

If they aren't too bad, go with a high volume oil pump and try again.

Personally, with 0-5 psi hot oil pressure, I would be doing a complete teardown.

Greg
 

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You sure the gauge is reliable? I'd try another one just to check, might save you from having to tear down the motor.
 

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If the oil is getting black quick , or before a normal oil change, then one has to think the rings are a bit weak.
As for oil pressure. If you have about 10 lbs. per 1k of rpm you should be ok.
Now if you can get to the pan and pull it. Then a bearing change would not hurt. Pump light be a bit weak and could replace it also.
This of course will not change the oil getting black quick, which is blowby.
Keep using the 10-30 is the proper oil. The heavy oil is not good for the motor, motors need flow not just pressure.
 

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Discussion Starter · #7 ·
I was wrong-it was not a rebuilt pump, it was new but not Ford or Melling. Put another gauge in the intake and had 10-12 lbs at hot idle so I'm gonna roll with it. I'll probably pull the engine this winter and replace bearings-I have to pull the engine to get the pan off so will do it all then.Gonna drive to and from Springfield-1900 miles-wish me luck guys-lol
 
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