Engine Hmm...is It The Gauge Or Am I In Trouble?

Discussion in 'Fox 5.0 Mustang Tech' started by deathb4dismount, Aug 31, 2013.


  1. deathb4dismount

    deathb4dismount Active Member

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    I was cruising just about 10 minutes ago on the highway. I was going 65 and fifth and decided to drop it into fourth for fun and hammer on it. As soon as it went in gear and I mashed the pedal I noticed the oil pressure gauge free fall to the red line. I thought it was working correctly so naturally I had a heart attack and coasted off the exit I almost zipped by and pulled into the nearest parking lot. I checked the oil and the level seemed good and didn't hear any ticking. I coasted to my house about a 1/2 mile away and everything still seemed good.

    Anyway sorry for the long story, now the tech question. If something is wrong with oil flow how can I check? If the oil pump quit when engine was turning close to 5k would that be catastrophic?
  2. mikestang63

    mikestang63 Mustang Master

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    Check the oil pressure sending unit wire and unit. You may have just kicked the wire off. If the oil pump or shaft broke at 5k you'd know.
    Grabbin' Asphalt likes this.
  3. stykthyn

    stykthyn Commander of the snuggie cultists

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    X2 on the sending unit. Any unusual vibes or smoke?
  4. vfast

    vfast Member

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    get a mechanical gauge
  5. Grabbin' Asphalt

    Grabbin' Asphalt Mustang Master

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    You'll hear a damn LOUD ASS SNAP that sends your heart into sheer panic!!! Ask me how I know :rolleyes:
  6. 7991LXnSHO

    7991LXnSHO Active Member

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    My stock oil pump shaft twisted like a strawberry twizzler after a rebuild. No noise or pop.
    Get a aftermarket gauge if the sender and wiring look OK.
  7. deathb4dismount

    deathb4dismount Active Member

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    I am in trouble. I installed a mechanical oil pressure gauge today and cranked it over. I figured I wouldn't get a reading until the engine warmed up but before it even reached temperature the whole engine started thumping. I shut down and started weaving a string of obscenity that lasted for a good 10 minutes. Am I looking for a new oil pump or shaft at this point or should I be looking for an explorer long block?
  8. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor Admin Dude

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    Mark the dizzy and pull it. Let us know what the shaft looks like. If it looks good then it's time to pull a valve cover and get an oil priming tool for a Ford 302 (it's quarter inch) from the parts store.


    It looks something like this.
    RX1431%20EARLY[1].jpg

    Toss that on the end of a drill and run the drill full speed backwards. If the pump is working, you'll see the oil pumping over the rocker arms etc. If the pump is bad, no oil.

    There is no reason at all to run the motor for even another second until this is done.
  9. deathb4dismount

    deathb4dismount Active Member

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    Thanks noobz, it looks like I have a new project for this weekend
  10. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor Admin Dude

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    Yeah... It's not time to panic just yet. Best case, you'll need a new oil pump rod. Worse case, a new pump so long as there's no engine damage already.

    For what it's worth, I'm not a believer in High volume oil pumps for street cars. There's really no reason for them IMO.
  11. mikestang63

    mikestang63 Mustang Master

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    X2. standard volume oil pump and a hardened shaft works for me. Hoping you just lunched the pump. When you prime the oil pump, pull a valve cover off and see if you get any oil coming through the top end. If you don't get sufficient pressure or hear any unusual noise when priming, time to drain the oil, check for metal, and probably pull the pan.
  12. deathb4dismount

    deathb4dismount Active Member

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    Ok, let me get this straight on how I should tackle this.

    1.) Pull dizzy and check oil shaft...if it is fubar, replace
    2.) Pull a valve cover prime oil pump and check for pressure
    3.) If there is pressure reseal and move to step 5
    4.) If no pressure replace oil pump continue to step 5
    5.) Drain oil, pray there is no metal, check for metal, if there is metal go to step 6
    6.) #%& all that %^* store car for winter and start saving for crate motor
  13. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor Admin Dude

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    There's more to step 6. It depends on what kind of metal you find.

    If you find a whole bunch of copper/brass material then that would be a good time to crap yourself.

    If you find material from oil pump and/or pump shaft well... Change the pump, shaft, and oil and have a nice day.
    7991LXnSHO likes this.
  14. 7991LXnSHO

    7991LXnSHO Active Member

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    Just in case you get to #6, I am warming up on a bugle to play Taps for the motor.:flag:
    Keep in mind the oil shaft MAY be held in by a clip from the bottom side between the oil pump and part of the block. Pulling a valve cover to check for pressure should not be needed. It will help verify oil is going all over and the pressure sending port or extension tube is not blocked. That would be unlikely, but I suppose it is possible if the filter vomited its guts in the motor or if the oil turned to tar without oil changes for many, many miles.
  15. 7991LXnSHO

    7991LXnSHO Active Member

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    I've been told by a reputable builder if you go racing without the proper return path for the oil and a bigger pan, all the oil can end up in the top end. And a dry pad is bad. The HV pump just takes extra power to pump more oil than you need. I'd only use one as a bandage for a motor that had low pressure and lots of extra clearances.
  16. Dave2000GT

    Dave2000GT Active Member

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    What was the gauge doing after that ? Did it just stay at 0 or did it start to build? Also, what does it normally cruise at ?

    I was concerned because my gauge would read like 1 notch above red give or take. When I pulled the dash to do my heater core a quick check revealed that the gauge would range between like 2 "notches" below red to just over halway up. It would not physically go past this point, probably installed off. So I don't worry about it.
  17. 7991LXnSHO

    7991LXnSHO Active Member

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    The manual is a great idea if you can not find a local mentor too.
  18. deathb4dismount

    deathb4dismount Active Member

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    I have been delayed in getting into this because I have been sick. I started tackling it Monday and ran into a delay getting the stupid strut towe brace off due to a stripped nut. Hopefully I will make some progress this weekend. Ill post results of what I find
  19. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Thanks to Stangnet member bubba-dough for helping to educate all of us by finding this article... :nice:

    http://www.mellingengine.com/Portals/5/pdf/pdf_catalog/high-volume-pumps.pdf You will need the Adobe Acrobat viewer which is also a free download – http://www.adobe.com/products/acrobat/readstep2.html

    From the Melling site, for those who didn't follow the link & read the tech note...

    [​IMG]

    High Volume Pumps: Advantages, Myths & Fables

    Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.

    The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

    A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

    The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

    Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

    That is what a high volume pump will do. Now let Is consider what it will not do.


    It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

    It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

    It will not wear out distributor gears. The load on the gear is directly related to the resistance to flow. Oil pressure is the measure of resistance to flow. The Ford 427 FE "side oiler" used a pump with relief valve set at 125 psi and it used a standard distributor gear. Distributor gear failures are usually caused by a worn gear on a new cam gear and/or worn bearings allowing misalignment.

    It will not cause foaming of the oil. With any oil pump, the excess oil not needed by the engine is recirculated within the pump. Any additional foaming is usually created by revving the engine higher. The oil thrown from the rod bearings is going faster and causes the foaming. This is why high performance engines use a windage tray.

    It will not cause spark scatter. Because of the pump pressure there is a load on the distributor gear. The number of teeth on the oil pump gears determine the number of impulses per revolution of the pump. In a SB Chevy there are seven teeth on each gear giving 14 impulses per revolution. At 6000 RPM the oil pump is turning 3000 RPM or 50 revolutions per second. To have an effect on the distributor, these impulses would have to vibrate the distributor gear through an intermediate shaft that has loose connections at both ends. Spark scatter is usually caused by weak springs in the points or dust inside the distributor cap.

    High volume pumps can be a big advantage if used where needed. If installed in an engine that does not need the additional volume, they will not create a problem. The additional flow will be recirculated within the pump.

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