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no oil pressure

Discussion in 'The Garage' started by bigbadchev84, Apr 8, 2005.

  1. bigbadchev84

    bigbadchev84 1/2 ton status

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    ok i know this isnt a chevy but i really need help on this, i have a 1978 ford f-150 with a 400m in it, the original motor had a flat cam in it, so i replaced the cam and timing chain, when i went to fire the thing back up it had like 5lbs of pressure, so i went and bought a hi-volume oil pump for it, when i was at the parts store, my buddy told me to check the main bearings, i did and they were scored really bad, so i found another 400m that a buddy told me about, i helped pull the motor out of the bronco, they drove it into the shop and all gauges were reading great. i get the thing home, re-gasket it and checked the bearings, they were a little worn so i replaced all main and rod bearings, installed my new cam out of the other motor, and installed the new hi-volume/pressure pump, i get it installed, fire it up and no pressure, ok so i destroyed the distributer that came with my new motor to make a priming tool, pulled the oil pressure sending unit out of the block and oil was squirting out, so i put it back together, fire it up and no oil pressure, what is the deal??? im getting sooo frustrated
     
  2. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    Could be a sending unit decided to fail at the same time all this is going on. Is the sending unit the same one that's been in the truck the whole time? The reason I ask is because I tried using an Auto Meter sending unit with the factory wire and it ruined the sending unit. So, apparently there are differences in the voltages, etc that they use.

    I've also been told not to trust electric oil pressure gauges, espcially as they get hot with the engine temp. My engine builder told me that they often have customers come back concerned about oil pressure being too low. They have the customer try a mechanical gauge and everything is fine.
     
  3. bigbadchev84

    bigbadchev84 1/2 ton status

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    yea i forgot to say i installed a tee so i have a mechanical and the original, when it is running you can hear the lifters not pumping up and clattering, i am running the old blocks distributer, i think im gonna go buy a new one tomorrow, i checked it and it didnt look stripped, but im not sure it is spinning
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    There are several things that could happen to cause no oil pressure. First is the driveshaft that runs between the distributor and the oil pump may have twisted and fell out or was never installed correctly when you installed the new pump, second is the cam you installed may have the cam journals ground to the wrong size and you're losing all your oil pressure at that point or third one of the oil galley plugs in the front of the engine has popped out and that is allowing the oil to drain back into the crankcase.
     
  5. bigbadchev84

    bigbadchev84 1/2 ton status

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    well i bought a new distributor today and still no luck, i know that the shaft is seated properly, i pulled the sending units out today while the motor was running and the oil just kinda of gurgled out, the cam is a brand new 252h comp cams and lifter setthis thing was oiling great before i freshend it up, i guess the cam must be bad cause it is the only thing i have not substituted out, and has been used in both motors
     

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